Email: pavel.hobza@uochb.cas.cz
Location: Institute of Organic Chemistry and Biochemistry , Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic
Phone: (+420 )220 410 311
Professional
Born October 21, 1946 in Prerov, Czech Republic
Professor in Physical Chemistry, Charles University, Prague, Czech Republic
Professor in Physical Chemistry, Palacky University, Olomouc, Czech Republic
World Class University Professor, Postech University, Pohang, Korea
Career
Institute of Hygiene and Epidemiology
1979,1982 Postdoctoral Fellow at the Universite de Montreal, Canada
1984,1986 Visiting Professor at the Universite de Montreal, Canada
1990 Research Associate at Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany and Technische Universität München, Germany
1990-1991 DFG-visiting professor, Technische Universität München, Germany
1991-2003 J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague
2000-2004 Research Center for Complex Molecular Systems and Biomolecules, head
2002-now Professor of Physical Chemistry, Charles University, Prague
2005-now Research Center for Biomolecules and Complex Molecular Systems, head
2003-now Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Department of Molecular Modelling, head
2005-now Professor of Physical Chemistry, Palacký University, Olomouc
Field of Scholary Interest
Quantum chemistry and computational chemistry, non-covalent interactions, structure and dynamics of molecular and biomolecular clusters and biomolecules, hydrogen-bonding and improper, blue-shifting hydrogen-bonding, halogen bonding, drug design
Education and Training
Faculty of Technical and Nuclear Physics, Czech Technical University, Prague, chemistry (M.Sc.)
Institute of Physical Chemistry, Czechoslovak Academy of Sciences, Prague, C.Sc. (Ph.D.)
Awards and Honors
D.Sc. from Institute of Chemical Technology, Prague (1988)
Prize of Czech Literary Fond (1981, 1989)
Deutsche Forschung Gemeinschaft Gastprofessor, Technische Universität München (1992)
Czech Learned Society (1996), member
European Academy of Arts, Sciences and Humanities (2000), member
Prize of Ministry of Education of the Czech Republic (2000)
Prize of the Academy of Sciences of the Czech Republic (2003)
The Royal Society of Chemistry (2005), fellow
The Photon Science Institute, University of Manchester (2006) , fellow
Distinguish Chair, Institute of Organic Chemistry and Biochemistry (2007)
Praemium Academiae, Academy of Sciences of the Czech Republic (2007)
Ceska hlava, Goverment of the Czech Republic(2008)
World Class University Professor, Postech University, Pohang, Korea (2009)
Publication activities:
396 papers in referred journals and 3 books.
Citation index
The total number of citations (ICI) until February, 2011 is more than 17000; value of Hirsch index amounts to 70
Thesis adviser
PH directed altogether 22 PhD students, 10 Diploma students and 4 postdoctoral fellows. At present he supervises 6 PhD students, 1 Diploma students and 7 postdoctoral fellows.
Oral presentations, invited talks at world symposia and international conferences:
more than 50 pleneary and invited lectures at international conferences and leading universities in Europe, USA and Asia in the last 5 years
Funding
-Praemium Academiae, Academy of Sciences of the Czech Republic (2007-12; 25 000 000 Cz crowns),PI
-Research Center for Complex Molecular Systems and Biomolecules, Ministry of Education of the Czech Republic (2000 – 4; 85 000 000 Cz crowns), head
-Research Center for Biomolecules and Complex Molecular Systems, Ministry of Education of the Czech Republic (2005 – 11; 98 000 000 Cz crowns), head
-NSF grants (2002-4 ; 2010-12 together with M.de Vries, University of California) PH is co-PI
-1995-present : 10 grants from Grant Agency of the Czech Republic and Grant Agency of the Academy of Sciences of the Czech Republic, PH is PI
Membership in Editorial Boards
Chemistry – A European Journal (2005-now)
Chemical Reviews (1994-2004)
Phys. Chem. Chem. Phys. (2004-now)
Chem. Phys. Chem. (2006-now)
Chem. Phys. (2006-now)
Collection of Czechoslov. Chem. Commun.(2006-now, Chairman)
Membership in Scientific and Govermental Commitees
Scientific Council of the Academy of Sciences of the Czech Republic
Research and Development Council of the Czech Republic
Scientific Council of the Faculty of Science, Palacky University
Ukázat publikace2012
J. Rezac, K. E. Riley, and P. Hobza, „Evaluation of the performance of post-Hartree-Fock methods in terms of
intermolecular distance in noncovalent complexes,“ JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 33, iss. 6, pp. 691-694, 2012.
[Bibtex]
@article ISI:000300003600011,
Author = Rezac, Jan and Riley, Kevin E. and Hobza, Pavel,
Title = Evaluation of the performance of post-Hartree-Fock methods in terms of
intermolecular distance in noncovalent complexes,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 2012,
Volume = 33,
Number = 6,
Pages = 691-694,
Month = MAR 5,
DOI = 10.1002/jcc.22899,
ISSN = 0192-8651,
Unique-ID = ISI:000300003600011,
M. Kraus, M. Pitonak, P. Hobza, M. Urban, and P. Neogrady, „Highly correlated calculations using optimized virtual orbital space
with controlled accuracy. Application to counterpoise corrected
interaction energy calculations,“ INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 112, iss. 4, pp. 948-959, 2012.
[Bibtex]
@article ISI:000299079200002,
Author = Kraus, Michal and Pitonak, Michal and Hobza, Pavel and Urban, Miroslav
and Neogrady, Pavel,
Title = Highly correlated calculations using optimized virtual orbital space
with controlled accuracy. Application to counterpoise corrected
interaction energy calculations,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 2012,
Volume = 112,
Number = 4,
Pages = 948-959,
Month = FEB 5,
DOI = 10.1002/qua.23014,
ISSN = 0020-7608,
Unique-ID = ISI:000299079200002,
J. Rezac and P. Hobza, „Advanced Corrections of Hydrogen Bonding and Dispersion for
Semiempirical Quantum Mechanical Methods,“ JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 8, iss. 1, pp. 141-151, 2012.
[Bibtex]
@article ISI:000298908500016,
Author = Rezac, Jan and Hobza, Pavel,
Title = Advanced Corrections of Hydrogen Bonding and Dispersion for
Semiempirical Quantum Mechanical Methods,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2012,
Volume = 8,
Number = 1,
Pages = 141-151,
Month = JAN,
DOI = 10.1021/ct200751e,
ISSN = 1549-9618,
Unique-ID = ISI:000298908500016,
2011
E. Munusamy, R. Sedlak, and P. Hobza, „On the Nature of the Stabilization of Benzene center dot center dot
center dot Dihalogen and Benzene center dot center dot center dot
Dinitrogen Complexes: CCSD(T)/CBS and DFT-SAPT Calculations,“ CHEMPHYSCHEM, vol. 12, iss. 17, pp. 3253-3261, 2011.
[Bibtex]
@article ISI:000297693200021,
Author = Munusamy, Elango and Sedlak, Robert and Hobza, Pavel,
Title = On the Nature of the Stabilization of Benzene center dot center dot
center dot Dihalogen and Benzene center dot center dot center dot
Dinitrogen Complexes: CCSD(T)/CBS and DFT-SAPT Calculations,
Journal = CHEMPHYSCHEM,
Year = 2011,
Volume = 12,
Number = 17,
Pages = 3253-3261,
Month = DEC 9,
Abstract = The structure and stabilization energies of benzene (and methylated
benzenes)-X2 (X=F, Cl, Br, N) complexes were investigated by performing
CCSD(T)/complete basis set limit and density functional
theory/symmetry-adapted perturbation theory (DFT-SAPT) calculations. The
global minimum of the benzene-dihalogen complexes corresponds to the
T-shaped structure, whereas that of benzene-dinitrogen corresponds to
the sandwich one. The different binding motifs of these complexes arise
from the different quadrupole moments of dihalogens and dinitrogen. The
different sign of the quadrupole moments of these diatomics is explained
based on the electrostatic potential (ESP). Whereas all dihalogens,
including difluorine, possess a positive sigma hole, such a positive
area of the ESP is completely missing in the case of dinitrogen.
Moreover, benzene-X(2) (X=Br, Cl) electrostatic, dispersion, induction,
and delta(HartreeFock) energies, we recapitulate that the former
complexes are stabilized mainly by dispersion energy, followed by
electrostatic energy, whereas the latter complexes are stabilized mostly
by the dispersion interaction. The charge-transfer energy of
benzene-dibromine complexes, and surprisingly, also of methylated
benzenes-dibromine complexes is only moderate, and thus, not responsible
for their stabilization. Benzene-dichlorine and benzene-dibromine
complexes can thus be characterized merely as complexes with a halogen
bond rather than as charge-transfer complexes.,
DOI = 10.1002/cphc.201100455,
ISSN = 1439-4235,
Unique-ID = ISI:000297693200021,
J. Rezac, K. E. Riley, and P. Hobza, „Extensions of the S66 Data Set: More Accurate Interaction Energies and
Angular-Displaced Nonequilibrium Geometries,“ JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 7, iss. 11, pp. 3466-3470, 2011.
[Bibtex]
@article ISI:000296597300002,
Author = Rezac, Jan and Riley, Kevin E. and Hobza, Pavel,
Title = Extensions of the S66 Data Set: More Accurate Interaction Energies and
Angular-Displaced Nonequilibrium Geometries,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2011,
Volume = 7,
Number = 11,
Pages = 3466-3470,
Month = NOV,
Abstract = We present two extensions of the recently published S66 data set
[Rezac, Riley, Hobza; DOI: 10.1021/ct2002946]. Interaction energies
for the equilibrium geometry complexes have been recalculated using a
triple-zeta basis set for the CCSD(T) term in the CCSD(T)/CBS scheme.
This allows for the extrapolation of this term to the complete basis set
limit, improving accuracy by almost 1 order of magnitude compared to the
scheme previously used for the S66 set. Now, we estimate the largest
error in the set to be about 1\%. Validation of several methods against
the new data indicates the exceptional robustness and accuracy of the
SCS-MI-CCSD method. The second extension improves the coverage of
nonequilibrium geometries. We introduce a new data set, S66a8, that
samples intermolecular angular degrees of freedom in the S66 complexes.
For each of the 66 complexes, eight displaced geometries have been
constructed, systematically sampling possible rotations of the monomers.
Interaction energies in this set are calculated at the CCSD(T)/CBS level
consistently with the earlier introduced S66x8 data set that samples the
intermolecular distance.,
DOI = 10.1021/ct200523a,
ISSN = 1549-9618,
Unique-ID = ISI:000296597300002,
J. Granatier, P. Lazar, M. Otyepka, and P. Hobza, „The Nature of the Binding of Au, Ag, and Pd to Benzene, Coronene, and
Graphene: From Benchmark CCSD(T) Calculations to Plane-Wave DFT
Calculations,“ JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 7, iss. 11, pp. 3743-3755, 2011.
[Bibtex]
@article ISI:000296597300030,
Author = Granatier, Jaroslav and Lazar, Petr and Otyepka, Michal and Hobza, Pavel,
Title = The Nature of the Binding of Au, Ag, and Pd to Benzene, Coronene, and
Graphene: From Benchmark CCSD(T) Calculations to Plane-Wave DFT
Calculations,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2011,
Volume = 7,
Number = 11,
Pages = 3743-3755,
Month = NOV,
Abstract = The adsorption of Ag, Au, and Pd atoms on benzene, coronene, and
graphene has been studied using post Hartree-Fock wave function theory
(CCSD(T), MP2) and density functional theory (M06-2X, DFT-D3, PBE,
vdW-DF) methods. The CCSD(T) benchmark binding energies for benzene-M (M
= Pd, Au, Ag) complexes are 19.7, 4.2, and 2.3 kcal/mol, respectively.
We found that the nature of binding of the three metals is different:
While silver binds predominantly through dispersion interactions, the
binding of palladium has a covalent character, and the binding of gold
involves a subtle combination of charge transfer and dispersion
interactions as well as relativistic effects. We demonstrate that the
CCSD(T) benchmark binding energies for benzene-M complexes can be
reproduced in plane-wave density functional theory calculations by
including a fraction of the exact exchange and a nonempirical van der
Waals correction (EE+vdW). Applying the EE+vdW method, we obtained
binding energies for the graphene-M (M = Pd, Au, Ag) complexes of 17.4,
5.6, and 4.3 kcal/mol, respectively. The trends in binding energies
found for the benzene M complexes correspond to those in coronene and
graphene complexes. DFT methods that use empirical corrections to
account for the effects of vdW interactions significantly overestimate
binding energies in some of the studied systems.,
DOI = 10.1021/ct200625h,
ISSN = 1549-9618,
Unique-ID = ISI:000296597300030,
V. Spiwok, P. Hobza, and J. Rezac, „Free-Energy Simulations of Hydrogen Bonding versus Stacking of
Nucleobases on a Graphene Surface,“ JOURNAL OF PHYSICAL CHEMISTRY C, vol. 115, iss. 40, pp. 19455-19462, 2011.
[Bibtex]
@article ISI:000295546100001,
Author = Spiwok, Vojtech and Hobza, Pavel and Rezac, Jan,
Title = Free-Energy Simulations of Hydrogen Bonding versus Stacking of
Nucleobases on a Graphene Surface,
Journal = JOURNAL OF PHYSICAL CHEMISTRY C,
Year = 2011,
Volume = 115,
Number = 40,
Pages = 19455-19462,
Month = OCT 13,
Abstract = It has been demonstrated by molecular modeling and experiments that free
nucleic acid bases form hydrogen-bonded complexes in vacuum but prefer
pi-pi stacking in partially and fully solvated systems. Here we show
using molecular dynamics simulations and metadynamics that the addition
of a surface (in this case a nanographene monolayer) reverts the
situation from stacking back to hydrogen bonding. Watson-Crick as well
as several non-Watson-Crick base pairs lying on a graphene surface are
significantly more stable in a water environment than a pi-pi-pi-stacked
graphene-base-base assembly. It illustrates that the thermodynamics of
nucleobase interactions results from a fine balance among hydrogen
bonding, stacking, and solvation, and that these effects must be
considered in molecular design.,
DOI = 10.1021/jp202491J,
ISSN = 1932-7447,
Unique-ID = ISI:000295546100001,
K. E. Riley and P. Hobza, „Strength and Character of Halogen Bonds in Protein-Ligand Complexes,“ CRYSTAL GROWTH & DESIGN, vol. 11, iss. 10, pp. 4272-4278, 2011.
[Bibtex]
@article ISI:000295488200006,
Author = Riley, Kevin E. and Hobza, Pavel,
Title = Strength and Character of Halogen Bonds in Protein-Ligand Complexes,
Journal = CRYSTAL GROWTH \& DESIGN,
Year = 2011,
Volume = 11,
Number = 10,
Pages = 4272-4278,
Month = OCT,
Abstract = In this study we investigate the strength and character of eight halogen
bonding interactions from six protein-ligand complexes. The halogen
bonding complexes investigated here were selected because of their
favorable halogen bond characteristics. Interaction energies of model
systems derived from protein-ligand complexes are computed at the
MP2/aug-cc-pVDZ level of theory, and the relative contributions of
electrostatics and dispersion are estimated by computing Delta
E(HF)/Delta E(MP2) ratios. The relationship between these ratios and
DFT-SAPT E(elec)/E(disp) results is calibrated using smaller model
systems in order to gain a qualitative understanding of the relative
roles that electrostatics and dispersion play in these halogen bonds.
Electrostatic potentials for the halogen bonding ligands are also
generated in order to study the relationship between halogen bond
strengths and halogen a-hole size (and charge). It is found that the
strength and character of the protein-ligand halogen bonds investigated
here are strongly dependent on geometric factors and a-hole
characteristics. Many of the halogen bonds studied here, especially
those with favorable geometric and electrostatic properties, are found
to be of sufficient magnitude to make significant contributions to
protein-ligand binding.,
DOI = 10.1021/cg200882f,
ISSN = 1528-7483,
Unique-ID = ISI:000295488200006,
S. Karthikeyan, R. Sedlak, and P. Hobza, „on the Nature of Stabilization in Weak, Medium, and Strong
Charge-Transfer Complexes: CCSD(T)/CBS and SAPT Calculations,“ JOURNAL OF PHYSICAL CHEMISTRY A, vol. 115, iss. 34, SI, pp. 9422-9428, 2011.
[Bibtex]
@article ISI:000294146400011,
Author = Karthikeyan, S. and Sedlak, Robert and Hobza, Pavel,
Title = on the Nature of Stabilization in Weak, Medium, and Strong
Charge-Transfer Complexes: CCSD(T)/CBS and SAPT Calculations,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2011,
Volume = 115,
Number = 34, SI,
Pages = 9422-9428,
Month = SEP 1,
Abstract = Weak, medium, and strong charge-transfer (CT) complexes containing
various electron donors (C(2)H(4), C(2)H(2), NH(3), NMe(3), HCN, H(2)O)
and acceptors (F(2), Cl(2), BH(3), SO(2)) were investigated at the
CCSD(T)/complete basis set (CBS) limit. The nature of the stabilization
for these CT complexes was evaluated on the basis of perturbative NBC
calculations and DFT-SAPT/CBS calculations. The structure of all of the
complexes was determined by the counterpoise-corrected gradient
optimization performed at the MP2/cc-pVTZ level, and most of complexes
possess a linear-like contact structure. The total stabilization
energies lie between 1 and 55 kcal/mol and the strongest complexes
contain BH3 as an electron acceptor. When ordering the electron donors
and electron acceptors on the basis of these energies, we obtain the
same order as that based on the perturbative E2 charge-transfer
energies, which provides evidence that the charge-transfer term is the
dominant energy contribution. The CCSD(T) correction term, defined as
the difference between the CCSD(T) and MP2 interaction energies, is
mostly small, which allows the investigation of the CT complexes of this
type at the ``cheap'' MP2/CBS level. In the case of weak and medium CT
complexes (with stabilization energy smaller than about 15 kcal/mol),
the dominant stabilization originates in the electrostatic term; the
dispersion as well as induction and delta(HF) terms covering the CT
energy contribution are, however, important as well. For strong CT
complexes, induction energy is the second (after electrostatic) most
important energy term. The role of the induction and delta(HF) terms is
unique and characteristic for CT complexes. For all CT complexes, the
CCSD(T)/CBS and DFT-SAPT/CBS stabilization energies are comparable, and
surprisingly, it is true even for very strong CT complexes with
stabilization energy close to 50 kcal/mol characteristic by substantial
charge transfer (more than 0.3 e). It is thus possible to conclude that
perturbative DFT-SAPT analysis is robust enough to be applied even for
dative-like complexes with substantial charge transfer.,
DOI = 10.1021/jp1112476,
ISSN = 1089-5639,
Unique-ID = ISI:000294146400011,
J. Rezac, K. E. Riley, and P. Hobza, „S66: A Well-balanced Database of Benchmark Interaction Energies Relevant
to Biomolecular Structures,“ JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 7, iss. 8, pp. 2427-2438, 2011.
[Bibtex]
@article ISI:000293662500012,
Author = Rezac, Jan and Riley, Kevin E. and Hobza, Pavel,
Title = S66: A Well-balanced Database of Benchmark Interaction Energies Relevant
to Biomolecular Structures,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2011,
Volume = 7,
Number = 8,
Pages = 2427-2438,
Month = AUG,
Abstract = With numerous new quantum chemistry methods being developed in recent
years and the promise of even more new methods to be developed in the
near future, it is clearly critical that highly accurate, well-balanced,
reference data for many different atomic and molecular properties be
available for the parametrization and validation of these methods. One
area of research that is of particular importance in many areas of
chemistry, biology, and material science is the study of noncovalent
interactions. Because these interactions are often strongly influenced
by correlation effects, it is necessary to use computationally expensive
high-order wave function methods to describe them accurately. Here, we
present a large new database of interaction energies calculated using an
accurate CCSD(T)/CBS scheme. Data are presented for 66 molecular
complexes, at their reference equilibrium geometries and at 8 points
systematically exploring their dissociation curves; in total, the
database contains 594 points: 66 at equilibrium geometries, and 528 in
dissociation curves. The data set is designed to cover the most common
types of noncovalent interactions in biomolecules, while keeping a
balanced representation of dispersion and electrostatic contributions.
The data set is therefore well suited for testing and development of
methods applicable to bioorganic systems. In addition to the benchmark
CCSD(T) results, we also provide decompositions of the interaction
energies by means of DFT-SAPT calculations. The data set was used to
test several correlated QM methods, including those parametrized
specifically for noncovalent interactions. Among these, the SCS-MI-CCSD
method outperforms all other tested methods, with a root-mean-square
error of 0.08 kcal/mol for the S66 data set.,
DOI = 10.1021/ct2002946,
ISSN = 1549-9618,
Unique-ID = ISI:000293662500012,
AND AFTER THE INTRODUCTION OF A TRUSTWIDE PROFORMA,“ AGE AND AGEING, vol. 40, iss. 2, pp. II17, 2011.
[Bibtex]
@article ISI:000293594600018,
Author = Illsley, A. and Hobza, P. and Wanklyn, P. and Belfield, P.,
Title = AUDIT OF STANDARDS OF DOCUMENTATION OF DEATH IN THE MEDICAL NOTES BEFORE
AND AFTER THE INTRODUCTION OF A TRUSTWIDE PROFORMA,
Journal = AGE AND AGEING,
Year = 2011,
Volume = 40,
Number = 2,
Pages = II17,
Month = AUG,
ISSN = 0002-0729,
Unique-ID = ISI:000293594600018,
A. M. Rijs, M. Kabelac, A. Abo-Riziq, P. Hobza, and M. S. de Vries, „Isolated Gramicidin Peptides Probed by IR Spectroscopy,“ CHEMPHYSCHEM, vol. 12, iss. 10, SI, pp. 1816-1821, 2011.
[Bibtex]
@article ISI:000293385000008,
Author = Rijs, Anouk M. and Kabelac, Martin and Abo-Riziq, Ali and Hobza, Pavel
and de Vries, Mattanjah S.,
Title = Isolated Gramicidin Peptides Probed by IR Spectroscopy,
Journal = CHEMPHYSCHEM,
Year = 2011,
Volume = 12,
Number = 10, SI,
Pages = 1816-1821,
Month = JUL 11,
Abstract = We report double-resonant IR/UV ion-dip spectroscopy of neutral
gramicidin peptides in the gas phase. The IR spectra of gramicidin A and
C, recorded in both the 1000 cm(-1) to 1800 cm(-1) and the 2700 to 3750
cm(-1) region, allow structural analysis. By studying this broad IR
range, various local intramolecular interactions are probed, and
complementary IR modes can be accessed. Ab initio quantum chemical
calculations are used to support the interpretation of the experimental
IR spectra. The comparison of the calculated frequencies with the
experimental IR spectrum probed via the strong infrared absorptions of
all the amide groups (NH stretch, C=O stretch and NH bend), shows
evidence for a helical structure in the gas phase, which is similar to
that in the condensed phase. Additionally, we show that to improve the
spectral resolution when studying large neutral molecular structures of
the size of gramicidin, the use of heavier carrier gas could be
advantageous.,
DOI = 10.1002/cphc.201100212,
ISSN = 1439-4235,
Unique-ID = ISI:000293385000008,
P. Dobes, J. Rezac, J. Fanfrlik, M. Otyepka, and P. Hobza, „Semiempirical Quantum Mechanical Method PM6-DH2X Describes the Geometry
and Energetics of CK2-Inhibitor Complexes Involving Halogen Bonds Well,
While the Empirical Potential Fails,“ JOURNAL OF PHYSICAL CHEMISTRY B, vol. 115, iss. 26, pp. 8581-8589, 2011.
[Bibtex]
@article ISI:000292281200025,
Author = Dobes, Petr and Rezac, Jan and Fanfrlik, Jindrich and Otyepka, Michal
and Hobza, Pavel,
Title = Semiempirical Quantum Mechanical Method PM6-DH2X Describes the Geometry
and Energetics of CK2-Inhibitor Complexes Involving Halogen Bonds Well,
While the Empirical Potential Fails,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2011,
Volume = 115,
Number = 26,
Pages = 8581-8589,
Month = JUL 7,
Abstract = In the present study, we have investigated complexes of CK2 protein
kinase with halogenated inhibitors by means of the advanced
semiempirical quantum mechanical (SQM) PM6 method (called PM6-DH2X),
which describes various types of noncovalent interactions including
halogen bonding well. The PM6-DH2X method provides reliable geometries
of those CK2 protein kinase-inhibitor complexes involving halogen bonds
that agree well with the X-ray crystal structures. When the Amber
empirical potential is applied, this agreement becomes considerably
worse. Similarly, the binding free energies determined by the PM6-DH2X
SQM method are much closer to the experimental inhibition constants than
those based on the Amber empirical potential.,
DOI = 10.1021/jp202149z,
ISSN = 1520-6106,
Unique-ID = ISI:000292281200025,
M. Kolar, T. Kubar, and P. Hobza, „On the Role of London Dispersion Forces in Biomolecular Structure
Determination,“ JOURNAL OF PHYSICAL CHEMISTRY B, vol. 115, iss. 24, pp. 8038-8046, 2011.
[Bibtex]
@article ISI:000291709500038,
Author = Kolar, Michal and Kubar, Tomas and Hobza, Pavel,
Title = On the Role of London Dispersion Forces in Biomolecular Structure
Determination,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2011,
Volume = 115,
Number = 24,
Pages = 8038-8046,
Month = JUN 23,
Abstract = A DNA dodecamer and the methyladenine... methylthymine (mA...mT) complex
in aqueous environment have been studied by means of molecular dynamics
simulation, with a modified force field accounting for the hypothetical
absence of London dispersion forces. Under these conditions, the
inA...mT complex is preserved, while the double-helical DNA oligomer
passes via an extended, ladder-like intermediate to a collapsed
structure. The results are interpreted in terms of stability and
specificity of the structure of studied complexes. While the hydrophobic
effect of the solvent accounts for the sufficient stabilization of the
complex, the appearance of the native biomolecular conformation is
attributed to the London dispersion forces. Thus, the London dispersion
seems to provide the native structure of a biomolecular complex with the
largest additional stabilization, preferring it among several (or many)
possible aggregated structures. The observations are affected by the
construction of the modified force field, and this effect is discussed
thoroughly. The fundamental issues are the coupling of the components of
the Lennard-Jones potential and the way to separate them. Based on the
observations, the description of nonbonded interactions with the current
biomolecular force fields is discussed. It is proposed that a novel
force field composed of physically correct components to describe
nonbonded interactions could exhibit more favorable performance in
certain up-to-date applications.,
DOI = 10.1021/jp202878d,
ISSN = 1520-6106,
Unique-ID = ISI:000291709500038,
D. Nachtigallova, A. J. A. Aquino, J. J. Szymczak, M. Barbatti, P. Hobza, and H. Lischka, „Nonadiabatic Dynamics of Uracil: Population Split among Different Decay
Mechanisms,“ JOURNAL OF PHYSICAL CHEMISTRY A, vol. 115, iss. 21, pp. 5247-5255, 2011.
[Bibtex]
@article ISI:000290914500003,
Author = Nachtigallova, Dana and Aquino, Adelia J. A. and Szymczak, Jaroslaw J.
and Barbatti, Mario and Hobza, Pavel and Lischka, Hans,
Title = Nonadiabatic Dynamics of Uracil: Population Split among Different Decay
Mechanisms,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2011,
Volume = 115,
Number = 21,
Pages = 5247-5255,
Month = JUN 2,
Abstract = Nonadiabatic dynamics simulations performed at the state-averaged CASSCF
method are reported for uracil. Supporting calculations on stationary
points and minima on the crossing seams have been performed at the
MR-CISD and CASPT2 levels. The dominant mechanism is characterized by
relaxation into the S(2) minimum of pi pi* character followed by the
relaxation to the S(1) minimum of n pi* character. This mechanism
contributes to the slower relaxation with a decay constant larger than
1.5 ps, in good agreement with the long time constants experimentally
observed. A minor fraction of trajectories decay to the ground state
with a time constant of about 0.7 Ps, which should be compared to the
experimentally observed short constant. The major part of trajectories
decaying with this time constant follows the pi pi* channel and hops
to the ground state via an ethylenic conical intersection. A
contribution of the relaxation proceeding via a ring-opening conical
intersection was also observed. The existence of these two latter
channels together with a reduced long time constant is responsible for a
significantly shorter lifetime of uracil compared to that of thymine.,
DOI = 10.1021/jp201327w,
ISSN = 1089-5639,
Unique-ID = ISI:000290914500003,
A. J. A. Aquino, D. Nachtigallova, P. Hobza, D. G. Truhlar, C. Haettig, and H. Lischka, „The Charge-Transfer States in a Stacked Nucleobase Dimer Complex: A
Benchmark Study,“ JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 32, iss. 7, pp. 1217-1227, 2011.
[Bibtex]
@article ISI:000288871100002,
Author = Aquino, Adelia J. A. and Nachtigallova, Dana and Hobza, Pavel and
Truhlar, Donald G. and Haettig, Christof and Lischka, Hans,
Title = The Charge-Transfer States in a Stacked Nucleobase Dimer Complex: A
Benchmark Study,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 2011,
Volume = 32,
Number = 7,
Pages = 1217-1227,
Month = MAY,
Abstract = Electronic singlet excitations of stacked adenine-thymine (AT) and
guanine-cytosine (GC) complexes have been investigated with respect to
local excitation and charge-transfer (CT) characters. Potential energy
curves for rigid displacement of the nucleobases have been computed to
establish the distance dependence of the CT states. The second-order
algebraic diagrammatic construction [ADC(2)] method served as
reference approach for comparison to a selected set of density
functionals used within the time-dependent density functional theory
(TD-DFT). Particular attention was dedicated to the performance of the
recently developed family of M06 functionals. The calculations for the
stacked complexes show that at the ADC(2) level, the lowest CT state is
S(6) for the AT and as S(4) for the GC pair. At the reference geometry,
the actual charge transferred is found to be 0.73 e for AT. In case of
GC, this amount is much smaller (0.17 e). With increasing separation of
the two nucleobases, the CT state is strongly destabilized. The M06-2X
version provides a relatively good reproduction of the ADC(2) results.
It avoids the serious overstabilization and overcrowding of the spectrum
found with the B3LYP functional. On the other hand, M06-HF destabilizes
the CT state too strongly. TD-DFT/M06-2X calculations in solution
(heptane, isoquinoline, and water) using the polarizable continuum model
show a stabilization of the CT state and an increase in CT character
with increasing polarity of the solvent. (C) 2010 Wiley Periodicals,
Inc. J Comput Chem 32: 1217-1227, 2011,
DOI = 10.1002/jcc.21702,
ISSN = 0192-8651,
Unique-ID = ISI:000288871100002,
M. Kolar, J. Fanfrlik, and P. Hobza, „Ligand Conformational and Solvation/Desolvation Free Energy in
Protein-Ligand Complex Formation,“ JOURNAL OF PHYSICAL CHEMISTRY B, vol. 115, iss. 16, pp. 4718-4724, 2011.
[Bibtex]
@article ISI:000289697300020,
Author = Kolar, Michal and Fanfrlik, Jindrich and Hobza, Pavel,
Title = Ligand Conformational and Solvation/Desolvation Free Energy in
Protein-Ligand Complex Formation,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2011,
Volume = 115,
Number = 16,
Pages = 4718-4724,
Month = APR 28,
Abstract = In this study, an extensive sampling of the conformational space of nine
HIV-1 protease inhibitors was performed, to estimate the uncertainty
with which a single conformation scoring scheme approximates the
ligand-protein bin ding fret. energy. The SMD implicit
solvation/desolvation energy and gas phase PM6-DH2 energy were
calculated for a set of lop conformations of each ligand. The
probability density functions of the energies were compared with the
values obtained from the single-conformation approach and from a short
ab initio molecular dynamics simulation. The relative uncertainty in the
score within the set of nine inhibitors was calculated to be 3.5
kcal.mol(-1) and 2.7 kcal.mol(-1) for the single-conformation and short
dynamics, respectively. These results, though limited to the
consideration of flexible ligands, provide a valuable insight into the
precision of rigid models in the current computer-aided drug design.,
DOI = 10.1021/jp2010265,
ISSN = 1520-6106,
Unique-ID = ISI:000289697300020,
J. Rezac and P. Hobza, „A halogen-bonding correction for the semiempirical PM6 method,“ CHEMICAL PHYSICS LETTERS, vol. 506, iss. 4-6, pp. 286-289, 2011.
[Bibtex]
@article ISI:000289505500032,
Author = Rezac, Jan and Hobza, Pavel,
Title = A halogen-bonding correction for the semiempirical PM6 method,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 2011,
Volume = 506,
Number = 4-6,
Pages = 286-289,
Month = APR 20,
Abstract = We analyse the failure of the semiempirical QM method PM6 to describe
halogen bonds and suggest an empirical correction that remedies this
problem. Owing to underestimated repulsion in the PM6 method, the
halogen-bond interaction energies are dramatically exaggerated and the
equilibrium distances are very short. This is addressed by a correction
parametrised for all halogens capable of halogen bonding (Cl, Br, and
I). The correction is applied on top of the dispersion correction,
forming the PM6-D2X method. A comparison with ab initio calculations
shows that the method is able to predict the interaction energy of
halogen bonds with an error of 10\%. (C) 2011 Elsevier B. V. All rights
reserved.,
DOI = 10.1016/j.cplett.2011.03.009,
ISSN = 0009-2614,
Unique-ID = ISI:000289505500032,
[Bibtex]
@article ISI:000291982806825,
Author = Svadlenak, Nathan and Ligare, Marshall and Gulian, Lisa E. and Callahan,
Michael P. and Gengeliczki, Zsolt and Nachtigalla, Dana and Hobza, Pavel
and de Vries, Mattanjah S.,
Title = Spectroscopy of isolated prebiotic nucleobases,
Journal = ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2011,
Volume = 241,
Month = MAR 27,
Note = 241st National Meeting and Exposition of the American-Chemical-Society
(ACS), Anaheim, CA, MAR 27-31, 2011,
Organization = Amer Chem Soc,
ISSN = 0065-7727,
Unique-ID = ISI:000291982806825,
P. Dobes, J. Fanfrlik, J. Rezac, M. Otyepka, and P. Hobza, „Transferable scoring function based on semiempirical quantum mechanical
PM6-DH2 method: CDK2 with 15 structurally diverse inhibitors,“ JOURNAL OF COMPUTER-AIDED MOLECULAR DESIGN, vol. 25, iss. 3, pp. 223-235, 2011.
[Bibtex]
@article ISI:000288179000005,
Author = Dobes, Petr and Fanfrlik, Jindrich and Rezac, Jan and Otyepka, Michal
and Hobza, Pavel,
Title = Transferable scoring function based on semiempirical quantum mechanical
PM6-DH2 method: CDK2 with 15 structurally diverse inhibitors,
Journal = JOURNAL OF COMPUTER-AIDED MOLECULAR DESIGN,
Year = 2011,
Volume = 25,
Number = 3,
Pages = 223-235,
Month = MAR,
Abstract = A semiempirical quantum mechanical PM6-DH2 method accurately covering
the dispersion interaction and H-bonding was used to score fifteen
structurally diverse CDK2 inhibitors. The geometries of all the
complexes were taken from the X-ray structures and were reoptimised by
the PM6-DH2 method in continuum water. The total scoring function was
constructed as an estimate of the binding free energy, i.e., as a sum of
the interaction enthalpy, interaction entropy and the corrections for
the inhibitor desolvation and deformation energies. The applied scoring
function contains a clear thermodynamical terms and does not involve any
adjustable empirical parameter. The best correlations with the
experimental inhibition constants (ln K (i)) were found for bare
interaction enthalpy (r (2) = 0.87) and interaction enthalpy corrected
for ligand desolvation and deformation energies (r (2) = 0.77); when the
entropic term was considered, however, the correlation becomes worse but
still acceptable (r (2) = 0.52). The resulting correlation based on the
PM6-DH2 scoring function is better than previously published function
based on various docking/scoring, SAR studies or advanced QM/MM
approach, however, the robustness is limited by number of available
experimental data used in the correlation. Since a very similar
correlation between the experimental and theoretical results was found
also for a different system of the HIV-1 protease, the suggested scoring
function based on the PM6-DH2 method seems to be applicable in drug
design, even if diverse protein-ligand complexes have to be ranked.,
DOI = 10.1007/s10822-011-9413-5,
ISSN = 0920-654X,
Unique-ID = ISI:000288179000005,
J. Rezac and P. Hobza, „Extrapolation and Scaling of the DFT-SAPT Interaction Energies toward
the Basis Set Limit,“ JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 7, iss. 3, pp. 685-689, 2011.
[Bibtex]
@article ISI:000287991300016,
Author = Rezac, Jan and Hobza, Pavel,
Title = Extrapolation and Scaling of the DFT-SAPT Interaction Energies toward
the Basis Set Limit,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2011,
Volume = 7,
Number = 3,
Pages = 685-689,
Month = MAR,
Abstract = The dispersion energy term in the symmetry-adapted perturbation theory
based on the density functional theory (DFT-SAPT) converges rather
slowly with basis set size. Accurate results for large complexes, where
only calculations in small basis sets are practical, can be obtained by
extrapolation to the complete basis set limit (CBS). In this paper, we
propose an extrapolation scheme with the variable exponent optimized
specifically for the DFT-SAPT calculations in correlation-consistent
basis sets with diffuse functions. Another way to improve the accuracy
term at no additional cost is to scale the dispersion term by a fixed
amount. We present the scaling factors averaged over a balanced set of
10 model complexes. The results of these schemes are compared to the
high-quality :DFT-SAPT/CBS interaction energies in small complexes
obtained by fitting to a series of basis sets up to aug-cc-pV5Z and to
the CCSD(T)/CBS interaction energies. It is shown that even the cheapest
extrapolation scheme yields results that are limited by the accuracy of
the DFT-SAPT approach rather than by the basis set convergence. Scaling
the dispersion term allows accurate interaction energies as well as
their components to be obtained using just the aug-cc-pVDZ basis set;
such a calculation can be applied to complexes consisting of up to 50
first-row atoms.,
DOI = 10.1021/ct200005p,
ISSN = 1549-9618,
Unique-ID = ISI:000287991300016,
K. E. Riley, M. Pitonak, J. Cerny, and P. Hobza, „On the Structure and Geometry of Biomolecular Binding Motifs
(Hydrogen-Bonding, Stacking, X-H center dot center dot center dot pi):
WFT and DFT Calculations (vol 6, pg 66, 2010),“ JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 7, iss. 3, pp. 807, 2011.
[Bibtex]
@article ISI:000287991300030,
Author = Riley, Kevin E. and Pitonak, Michal and Cerny, Jir and Hobza, Pavel,
Title = On the Structure and Geometry of Biomolecular Binding Motifs
(Hydrogen-Bonding, Stacking, X-H center dot center dot center dot pi):
WFT and DFT Calculations (vol 6, pg 66, 2010),
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2011,
Volume = 7,
Number = 3,
Pages = 807,
Month = MAR,
DOI = 10.1021/ct200019g,
ISSN = 1549-9618,
Unique-ID = ISI:000287991300030,
S. Maity, N. G. Patwari, R. Sedlak, and P. Hobza, „A pi-stacked phenylacetylene dimer,“ PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 13, iss. 37, pp. 16706-16712, 2011.
[Bibtex]
@article ISI:000294501700029,
Author = Maity, Surajit and Patwari, G. Naresh and Sedlak, Robert and Hobza,
Pavel,
Title = A pi-stacked phenylacetylene dimer,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2011,
Volume = 13,
Number = 37,
Pages = 16706-16712,
Abstract = The structure of the phenylacetylene-dimer has been elucidated using
IR-UV double resonance spectroscopy in combination with high level ab
initio calculations at the CCSD(T)/CBS level. The IR spectra in the
acetylenic and the aromatic C-H stretching regions indicate that the two
phenylacetylene moieties are in identical environments and very similar
to the phenylacetylene monomer. Calculated stabilization energies and
the free energies at the CCSD(T)/CBS level favor the formation of an
anti-parallel pi-stacked structure. The DFT-SAPT energy decomposition
analysis points out that the anti-parallel pi-stacked structure
maximizes electrostatic as well as the dispersion components of energy.
The observed IR spectra are consistent with the anti-parallel pi-stacked
structure.,
DOI = 10.1039/c1cp20677j,
ISSN = 1463-9076,
Unique-ID = ISI:000294501700029,
O. Prenosil, M. Pitonak, R. Sedlak, M. Kabelac, and P. Hobza, „H-Bonding Cooperativity Effects in Amyloids: Quantum Mechanical and
Molecular Mechanics Study,“ ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH
IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS, vol. 225, iss. 5, SI, pp. 553-574, 2011.
[Bibtex]
@article ISI:000292526800008,
Author = Prenosil, Ondrej and Pitonak, Michal and Sedlak, Robert and Kabelac,
Martin and Hobza, Pavel,
Title = H-Bonding Cooperativity Effects in Amyloids: Quantum Mechanical and
Molecular Mechanics Study,
Journal = ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH
IN PHYSICAL CHEMISTRY \& CHEMICAL PHYSICS,
Year = 2011,
Volume = 225,
Number = 5, SI,
Pages = 553-574,
Abstract = The cooperativity effects have been evaluated on three model systems,
the formamide, (formylamino)acetamide and amyloidic-layer oligomers with
an increasing size of the monomer units (6, 13 and 214 atoms). In the
last model, each layer is a dimer of the amino-acid sequence GNNQQNY in
one-letter amino-acid abbreviations. The series of oligomers for each
model system of up to six monomers have been constructed. For the
calculation of the strength of a particular H-bond formed between
various sub-oligomers within an oligomer, different wave function,
density functional and semi-empirical quantum mechanical methods as well
as empirical force fields have been used.
Semi-empirical methods are found to be a reasonable compromise between
accuracy and computational cost. These methods are able to describe the
cooperativity effects with an accuracy almost comparable to that of the
ab initio methods. On the contrary, the empirical force-field methods
for all of the model systems mostly failed to describe the H-bonding
cooperativity effects properly. Based on the results obtained in this
work, we recommend using semi-empirical methods. For the systems where
this is impossible, we agree to use polarizable force fields with some
reservations.
Generally, the more flexible the oligomer chain is (the less steric the
repulsion or rigid motifs are), the larger the cooperativity that can be
achieved. With the increasing number of monomers in a sequence connected
via H-bonds, the cooperativity effects appear to be growing, but
relatively soon (at 3-4 monomer units) they tend to become saturated.,
DOI = 10.1524/zpch.2011.0109,
ISSN = 0942-9352,
Unique-ID = ISI:000292526800008,
T. Zeleny, P. Hobza, D. Nachtigallova, M. Ruckenbauer, and H. Lischka, „PHOTODYNAMICS OF THE ADENINE MODEL 4-AMINOPYRIMIDINE EMBEDDED WITHIN
DOUBLE STRAND OF DNA,“ COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 76, iss. 6, pp. 631-643, 2011.
[Bibtex]
@article ISI:000291434900001,
Author = Zeleny, Tomas and Hobza, Pavel and Nachtigallova, Dana and Ruckenbauer,
Matthias and Lischka, Hans,
Title = PHOTODYNAMICS OF THE ADENINE MODEL 4-AMINOPYRIMIDINE EMBEDDED WITHIN
DOUBLE STRAND OF DNA,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2011,
Volume = 76,
Number = 6,
Pages = 631-643,
Abstract = On-the-fly surface hopping nonadiabatic photodynamical simulations using
hybrid quantum mechanical/molecular mechanical approach of
4-aminopyrimidine were performed to model the relaxation mechanism of
adenine within DNA double strand. The surrounding bases do not affect
the overall ring-puckering relaxation mechanisms significantly, however,
interesting hydrogen-bond dynamics is observed. First, formation of
intra-strand hydrogen bonds is found. It is shown that this effect
speeds up the decay process. In addition, the Watson-Crick structure is
altered by breaking one of the inter-strand hydrogen bonds also leading
to a decrease of the life time.,
DOI = 10.1135/cccc2011046,
ISSN = 0010-0765,
Unique-ID = ISI:000291434900001,
M. Pitonak, F. Aquilante, P. Hobza, P. Neogrady, J. Noga, and M. Urban, „PARALLELIZED IMPLEMENTATION OF THE CCSD(T) METHOD IN MOLCAS USING
OPTIMIZED VIRTUAL ORBITALS SPACE AND CHOLESKY DECOMPOSED TWO-ELECTRON
INTEGRALS,“ COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 76, iss. 6, pp. 713-742, 2011.
[Bibtex]
@article ISI:000291434900006,
Author = Pitonak, Michal and Aquilante, Francesco and Hobza, Pavel and Neogrady,
Pavel and Noga, Jozef and Urban, Miroslav,
Title = PARALLELIZED IMPLEMENTATION OF THE CCSD(T) METHOD IN MOLCAS USING
OPTIMIZED VIRTUAL ORBITALS SPACE AND CHOLESKY DECOMPOSED TWO-ELECTRON
INTEGRALS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2011,
Volume = 76,
Number = 6,
Pages = 713-742,
Abstract = Parallelized implementation of the coupled cluster singles doubles with
non-iterative triples in the MOLCAS program suite is described. The code
benefits from the Cholesky decomposition of two-electron integrals and
the algorithm is particularly designed for calculations using reduced
optimized virtual orbital space. Different aspects of parallelization
and its efficiency are discussed based on our recent successful
calculations for medium sized molecules involving more than 1000 basis
functions.,
DOI = 10.1135/cccc2011048,
ISSN = 0010-0765,
Unique-ID = ISI:000291434900006,
A. Pecina, O. Prenosil, J. Fanfrlik, J. Rezac, J. Granatier, P. Hobza, and M. Lepsik, „ON THE RELIABILITY OF THE CORRECTED SEMIEMPIRICAL QUANTUM CHEMICAL
METHOD (PM6-DH2) FOR ASSIGNING THE PROTONATION STATES IN HIV-1
PROTEASE/INHIBITOR COMPLEXES,“ COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 76, iss. 5, pp. 457-479, 2011.
[Bibtex]
@article ISI:000290280100009,
Author = Pecina, Adam and Prenosil, Ondrej and Fanfrlik, Jindrich and Rezac, Jan
and Granatier, Jaroslav and Hobza, Pavel and Lepsik, Martin,
Title = ON THE RELIABILITY OF THE CORRECTED SEMIEMPIRICAL QUANTUM CHEMICAL
METHOD (PM6-DH2) FOR ASSIGNING THE PROTONATION STATES IN HIV-1
PROTEASE/INHIBITOR COMPLEXES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2011,
Volume = 76,
Number = 5,
Pages = 457-479,
Abstract = A novel computational protocol for determining the most probable
protonation states in protein/ligand complexes is presented. The method
consists in treating large parts of the enzyme using the corrected
semiempirical quantum chemical (QM) method - PM6-D2 for optimization and
PM6-DH2 for single-point energies - while the rest is calculated using
molecular mechanics (MM) within a hybrid QM/MM fashion. The surrounding
solvent is approximated by an implicit model. This approach is applied
to two model systems, two different carboxylate pairs in one general and
one unique HIV-1 protease/inhibitor complex. The effect of the size of
the movable QM part is investigated in a series of several sizes, 3-,
6-, 8-and 10-angstrom regions surrounding the inhibitor. For the
smallest region (< 450 atoms) the computationally more costly DFT QM/MM
optimizations are performed as a check of the correctness. Proton
transfer (PT) phenomena occur at both the PM6-D2 and DFT levels, which
underlines the requirement for a QM approach. The barriers of PT are
checked in model carboxylic acid pairs using the highly accurate MP2 and
CCSD(T) values. An important result of this study is the fine-tuning of
the protocol which can be used in further applications; its limitations
are also shown, pointing to future developments. The calculations reveal
which protonation variants of the active site are the most stable. In
conclusion, the presented protocol can also be utilized for defining
probable isomers in biomolecular systems. It can also serve as a
preparatory step for further interaction-energy and binding-score
calculations.,
DOI = 10.1135/cccc2011035,
ISSN = 0010-0765,
Unique-ID = ISI:000290280100009,
W. Zierkiewicz, R. Wieczorek, P. Hobza, and D. Michalska, "Halogen bonded complexes between volatile anaesthetics (chloroform,
halothane, enflurane, isoflurane) and formaldehyde: a theoretical study," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 13, iss. 11, pp. 5105-5113, 2011.
[Bibtex]
@article ISI:000287930100039,
Author = Zierkiewicz, Wiktor and Wieczorek, Robert and Hobza, Pavel and
Michalska, Danuta,
Title = Halogen bonded complexes between volatile anaesthetics (chloroform,
halothane, enflurane, isoflurane) and formaldehyde: a theoretical study,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2011,
Volume = 13,
Number = 11,
Pages = 5105-5113,
Abstract = The structures and intermolecular interactions in the halogen bonded
complexes of anaesthetics (chloroform, halothane, enflurane and
isoflurane) with formaldehyde were studied by ab initio MP2 and CCSD(T)
methods. The CCSD(T)/CBS calculated binding energies of these complexes
are between -2.83 and -4.21 kcal mol(-1). The largest stabilization
energy has been found for the C-Br center dot center dot center dot O
bonded halothane center dot center dot center dot OCH(2) complex. In all
complexes the C-X bond length (where X = Cl, Br) is slightly shortened,
in comparison to a free compound, and an increase of the C-X stretching
frequency is observed. The electrostatic interaction was excluded as
being responsible for the C-X bond contraction. It is suggested that
contraction of the C-X bond length can be explained in terms of the
Pauli repulsion (the exchange overlap) between the electron pairs of
oxygen and halogen atoms in the investigated complexes. This is
supported by the DFT-SAPT results, which indicate that the repulsive
exchange energy overcompensates the electrostatic one. Moreover, the
dispersion and electrostatic contributions cover about 95\% of the total
attraction forces, in these complexes.,
DOI = 10.1039/c0cp02085k,
ISSN = 1463-9076,
Unique-ID = ISI:000287930100039,
2010
M. Barbatti, A. J. A. Aquino, J. J. Szymczak, D. Nachtigallova, P. Hobza, and H. Lischka, "Relaxation mechanisms of UV-photoexcited DNA and RNA nucleobases," PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF
AMERICA, vol. 107, iss. 50, pp. 21453-21458, 2010.
[Bibtex]
@article ISI:000285521500044,
Author = Barbatti, Mario and Aquino, Adelia J. A. and Szymczak, Jaroslaw J. and
Nachtigallova, Dana and Hobza, Pavel and Lischka, Hans,
Title = Relaxation mechanisms of UV-photoexcited DNA and RNA nucleobases,
Journal = PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF
AMERICA,
Year = 2010,
Volume = 107,
Number = 50,
Pages = 21453-21458,
Month = DEC 14,
Abstract = A comprehensive effort in photodynamical ab initio simulations of the
ultrafast deactivation pathways for all five nucleobases adenine,
guanine, cytosine, thymine, and uracil is reported. These simulations
are based on a complete nonadiabatic surface-hopping approach using
extended multiconfigurational wave functions. Even though all five
nucleobases share the basic internal conversion mechanisms, the
calculations show a distinct grouping into purine and pyrimidine bases
as concerns the complexity of the photodynamics. The purine bases
adenine and guanine represent the most simple photodeactivation
mechanism with the dynamics leading along a diabatic pi pi* path
directly and without barrier to the conical intersection seam with the
ground state. In the case of the pyrimidine bases, the dynamics starts
off in much flatter regions of the pi pi* energy surface due to
coupling of several states. This fact prohibits a clear formation of a
single reaction path. Thus, the photodynamics of the pyrimidine bases is
much richer and includes also n pi* states with varying importance,
depending on the actual nucleobase considered. Trapping in local minima
may occur and, therefore, the deactivation time to the ground state is
also much longer in these cases. Implications of these findings are
discussed (i) for identifying structural possibilities where
singlet/triplet transitions can occur because of sufficient retention
time during the singlet dynamics and (ii) concerning the flexibility of
finding other deactivation pathways in substituted pyrimidines serving
as candidates for alternative nucleobases.,
DOI = 10.1073/pnas.1014982107,
ISSN = 0027-8424,
Unique-ID = ISI:000285521500044,
R. Sedlak, J. Fanfrlik, D. Hnyk, P. Hobza, and M. Lepsik, "Interactions of Boranes and Carboranes with Aromatic Systems: CCSD(T)
Complete Basis Set Calculations and DFT-SAPT Analysis of Energy
Components," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 114, iss. 42, pp. 11304-11311, 2010.
[Bibtex]
@article ISI:000283106200037,
Author = Sedlak, Robert and Fanfrlik, Jindrich and Hnyk, Drahomir and Hobza,
Pavel and Lepsik, Martin,
Title = Interactions of Boranes and Carboranes with Aromatic Systems: CCSD(T)
Complete Basis Set Calculations and DFT-SAPT Analysis of Energy
Components,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2010,
Volume = 114,
Number = 42,
Pages = 11304-11311,
Month = OCT 28,
Abstract = The noncovalent interactions of heteroboranes with aromatic systems have
only recently been acknowledged as a source of stabilization in
supramolecular complexes. The physical basis of these interactions has
been studied in several model complexes using advanced computational
methods. The highly accurate CCSD(T)/complete basis set (CBS) value of
the interaction energy for the model diborane center dot center dot
center dot benzene complex in a stacking geometry exhibiting a B(2)H
center dot center dot center dot pi hydrogen bond was calculated to be
-4.0 kcal center dot mol(-1). The DFT-SAPT/CBS approach, which is shown
to reproduce the CCSD(T)/CBS data reliably asserted that the major
stabilizing component was dispersion, followed by electrostatics.
Furthermore, the effect of the benzene heteroatom- and exosubstitutions
was studied and found to be small. Next, when aromatic molecules were
changed to cyclic aliphatic ones, van der Waals complexes stabilized by
the dispersion term only were formed. As the last step, interactions of
two larger icosahedral borane cages with benzene were explored. The
complex of the monoanionic CB(11)H(12)(-) exhibited two minima: the
first stacked above the plane of the benzene ring with a C-H center dot
center dot center dot pi hydrogen bond and the second planar, in which
the carborane cage bound to benzene via five B-H center dot center dot
center dot H-C dihydrogen bonds. The DFT-SAPT/CBS calculations revealed
that both of these binding motifs were stabilized by dispersion followed
by electrostatic terms, with the planar complex being 1.4 kcal center
dot mol(-1) more stable than the stacked one. The dianionic
B(12)H(12)(2-) interacted with benzene only in the planar geometry,
similarly as smaller anions do. The large stabilization energy of 11.0
kcal center dot mol(-1) was composed of dominant attractive dispersion
and slightly smaller electrostatic and induction terms. In summary, the
borane/carborane center dot center dot center dot aromatic interaction
is varied both in the complex geometries and in the stabilizing energy
components. The detailed insight derived from high-level quantum
chemical computations can help us understand such important processes as
host-guest complexation or carborane center dot center dot center dot
biomolecule interactions.,
DOI = 10.1021/jp104411x,
ISSN = 1089-5639,
Unique-ID = ISI:000283106200037,
M. Kolar, T. Kubar, and P. Hobza, "Sequence-Dependent Configurational Entropy Change of DNA upon
Intercalation," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 114, iss. 42, pp. 13446-13454, 2010.
[Bibtex]
@article ISI:000283110500024,
Author = Kolar, Michal and Kubar, Tomas and Hobza, Pavel,
Title = Sequence-Dependent Configurational Entropy Change of DNA upon
Intercalation,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2010,
Volume = 114,
Number = 42,
Pages = 13446-13454,
Month = OCT 28,
Abstract = We investigated the intercalation of an antitumor drug ellipticine into
four adenine-thymine (AT) rich DNA duplexes with the focus on the
configurational entropy, by means of molecular dynamics (MD)
simulations. Two possible binding orientations of ellipticine in a DNA
double helix were studied, and the orientation with the pyrrole nitrogen
exposed into a major groove was identified as the more probable. The
configurational entropy change of DNA is shown to contribute
significantly to the binding free energy. The magnitude of this
contribution depends on the exact DNA sequence. A detailed analysis
revealed that the largest flexibility changes occurred in the
sugar-phosphate backbone, resulting in an entropy gain in the most
cases. The nucleobases were not involved in the changes of flexibility
and entropy. BI/BII-like conformational transitions were observed after
the intercalation of ellipticine, and the consequences of these
transitions for the evaluation of entropy are discussed.,
DOI = 10.1021/jp1019153,
ISSN = 1520-6106,
Unique-ID = ISI:000283110500024,
J. Fanfrlik, A. K. Bronowska, J. Rezac, O. Prenosil, J. Konvalinka, and P. Hobza, "A Reliable Docking/Scoring Scheme Based on the Semiempirical Quantum
Mechanical PM6-DH2 Method Accurately Covering Dispersion and H-Bonding:
HIV-1 Protease with 22 Ligands," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 114, iss. 39, pp. 12666-12678, 2010.
[Bibtex]
@article ISI:000282209900029,
Author = Fanfrlik, Jindrich and Bronowska, Agnieszka K. and Rezac, Jan and
Prenosil, Ondiej and Konvalinka, Jan and Hobza, Pavel,
Title = A Reliable Docking/Scoring Scheme Based on the Semiempirical Quantum
Mechanical PM6-DH2 Method Accurately Covering Dispersion and H-Bonding:
HIV-1 Protease with 22 Ligands,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2010,
Volume = 114,
Number = 39,
Pages = 12666-12678,
Month = OCT 7,
Abstract = In this study, we introduce a fast and reliable rescoring scheme for
docked complexes based on a semiempirical quantum mechanical PM6-DH2
method. The method utilizes a PM6-based Hamiltonian with corrections for
dispersion energy and hydrogen bonds. The total score is constructed as
the sum of the PM6-DH2 interaction enthalpy, the empirical force field
(AMBER) interaction entropy, and the sum of the deformation (PM6-SMD)
and the desolvation (SMD) energies of the ligand. The main advantage of
the procedure is the fact that we do not add any empirical parameter for
either an individual component of the total score or an individual
protein ligand complex. This rescoring method is applied to a very
challenging system, namely, the HIV-1 protease with a set of ligands. As
opposed to the conventional DOCK procedure, the 13M6-DH2 rescoring based
on all of the terms distinguishes between binders and nonbinders and
provides a reliable correlation of the theoretical and experimental
binding free energies. Such a dramatic improvement, resulting from the
PM6-DH2 rescoring of all the complexes, provides a valuable yet
inexpensive tool for rational drug discovery and de novo ligand design.,
DOI = 10.1021/jp1032965,
ISSN = 1520-6106,
Unique-ID = ISI:000282209900029,
D. Nachtigallova, M. Barbatti, J. J. Szymczak, P. Hobza, and H. Lischka, "The photodynamics of 2,4-diaminopyrimidine in comparison with
4-aminopyrimidine: The effect of amino-substitution," CHEMICAL PHYSICS LETTERS, vol. 497, iss. 1-3, pp. 129-134, 2010.
[Bibtex]
@article ISI:000281526700027,
Author = Nachtigallova, Dana and Barbatti, Mario and Szymczak, Jaroslaw J. and
Hobza, Pavel and Lischka, Hans,
Title = The photodynamics of 2,4-diaminopyrimidine in comparison with
4-aminopyrimidine: The effect of amino-substitution,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 2010,
Volume = 497,
Number = 1-3,
Pages = 129-134,
Month = SEP 10,
Abstract = Nonadiabatic photodynamical surface hopping simulations of
4-aminopyrimidine and 2,4-diaminopyrimidine were performed at
multi-configurational level. Additional NH(2) substitution blocks part
of the ring puckering modes necessary to reach ultrafast deactivation
channels but does not affect the excited-state lifetime of
2,4-diaminopyrimidine significantly since other pathways leading to
ultrafast relaxation can be utilized.
The effect of the excess energy on the relaxation mechanism of
2,4-diaminopyrimidine was studied. It is shown that the amount of
initial energy influences the time to reach the crossing seam and thus
the lifetime. This study is important when interpreting the experimental
results performed at different pump energies. (C) 2010 Elsevier B.V. All
rights reserved.,
DOI = 10.1016/j.cplett.2010.07.098,
ISSN = 0009-2614,
Unique-ID = ISI:000281526700027,
K. E. Riley, M. Pitonak, P. Jurecka, and P. Hobza, "Stabilization and Structure Calculations for Noncovalent Interactions in
Extended Molecular Systems Based on Wave Function and Density Functional
Theories," CHEMICAL REVIEWS, vol. 110, iss. 9, pp. 5023-5063, 2010.
[Bibtex]
@article ISI:000281840400003,
Author = Riley, Kevin E. and Pitonak, Michel and Jurecka, Petr and Hobza, Pavel,
Title = Stabilization and Structure Calculations for Noncovalent Interactions in
Extended Molecular Systems Based on Wave Function and Density Functional
Theories,
Journal = CHEMICAL REVIEWS,
Year = 2010,
Volume = 110,
Number = 9,
Pages = 5023-5063,
Month = SEP,
DOI = 10.1021/cr1000173,
ISSN = 0009-2665,
Unique-ID = ISI:000281840400003,
M. Kolar, K. Berka, P. Jurecka, and P. Hobza, "On the Reliability of the AMBER Force Field and its Empirical Dispersion
Contribution for the Description of Noncovalent Complexes," CHEMPHYSCHEM, vol. 11, iss. 11, pp. 2399-2408, 2010.
[Bibtex]
@article ISI:000281061500018,
Author = Kolar, Michal and Berka, Karel and Jurecka, Petr and Hobza, Pavel,
Title = On the Reliability of the AMBER Force Field and its Empirical Dispersion
Contribution for the Description of Noncovalent Complexes,
Journal = CHEMPHYSCHEM,
Year = 2010,
Volume = 11,
Number = 11,
Pages = 2399-2408,
Month = AUG 2,
Abstract = The reliability of the AMBER force field is tested by comparing the
total interaction energy and dispersion energy with the reference data
obtained at the density functional theory symmetry-adapted perturbation
treatment (DFT-SAPT)/aug-cc-pVDZ level. The comparison is made for 194
different geometries of noncovalent complexes (H-bonded, stacked, mixed,
and dispersion-bound), at the equilibrium distances as well as at longer
distances (up to a relative distance of two). The total interaction
energies agree very well with the reference data and only the strength
of H-bonded complexes is slightly underestimated. In the case of
dispersion energy, the overall agreement is even better, with the
exception of the stacked aromatic systems, where the empirical
dispersion energy is overestimated. The use of AMBER interaction energy
and AMBER dispersion energy for different types of noncovalent complexes
at equilibrium as well as at longer distances is thus justified, except
for, a few cases, such as the water molecule, where the dispersion
energy is highly inaccurate.,
DOI = 10.1002/cphc.201000109,
ISSN = 1439-4235,
Unique-ID = ISI:000281061500018,
L. Grafova, M. Pitonak, J. Rezac, and P. Hobza, "Comparative Study of Selected Wave Function and Density Functional
Methods for Noncovalent Interaction Energy Calculations Using the
Extended S22 Data Set," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 6, iss. 8, pp. 2365-2376, 2010.
[Bibtex]
@article ISI:000280661600010,
Author = Grafova, Lucie and Pitonak, Michal and Rezac, Jan and Hobza, Pavel,
Title = Comparative Study of Selected Wave Function and Density Functional
Methods for Noncovalent Interaction Energy Calculations Using the
Extended S22 Data Set,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2010,
Volume = 6,
Number = 8,
Pages = 2365-2376,
Month = AUG,
Abstract = In this paper, an extension of the S22 data set of Jurecka et at
(Jurecka, P, Sponer, J, Cerny, J; Hobza, P. Phys. Chem. Chem. Phys 2006,
8, 1985), the data set of benchmark CCSD(T)/CBS interaction energies of
twenty-two noncovalent complexes in equilibrium geometries, is presented
The S22 data set has been extended by including the stretched (one
shortened and three elongated) complex geometries of the S22 data set
along the main noncovalent interaction coordinate The goal of this work
is to assess the accuracy of the popular wave function methods (MP2-,
MP3- and, CCSD-based) and density functional methods (with and without
empirical correction for the dispersion energy) for noncovalent
complexes based on a statistical evaluation not only in equilibrium, but
also in nonequilibrium geometries The results obtained in this work
provide information on whether an accurate and balanced description of
the different interaction types and complex geometry distortions can be
expected from the tested methods This information has an important
implication in the calculation of large molecular complexes, where the
number of distant interacting molecular fragments, often in far from
equilibrium geometries, increases rapidly with the system size The best
performing WFT methods were found to be the SCS-CCSD (spin-component
scaled CCSD, according to Takatani, T, Hohenstein, E. G., Sherrill, C D
J Chem. Phys 2008, 128, 124111), MP2C (dispersion-corrected MP2,
according to Hesselmann, A J Chem. Phys 2008, 128, 144112), and MP2 5
(scaled MP3, according to Pitonak, M., Neogrady, P., Cerny, J; Grimme,
S., Hobza, P. ChemPhysChem 2009, 10, 282.) Since none of the OFT methods
fulfilled the required statistical criteria proposed in this work, they
cannot be generally recommended for large-scale calculations The DFT
methods still have the potential to deliver accurate results for large
molecules, but most likely on the basis of an error cancellation.,
DOI = 10.1021/ct1002253,
ISSN = 1549-9618,
Unique-ID = ISI:000280661600010,
K. Berka, R. A. Laskowski, P. Hobza, and J. Vondrasek, "Energy Matrix of Structurally Important Side-Chain/Side-Chain
Interactions in Proteins," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 6, iss. 7, pp. 2191-2203, 2010.
[Bibtex]
@article ISI:000279751500026,
Author = Berka, Karel and Laskowski, Roman A. and Hobza, Pavel and Vondrasek,
Jiri,
Title = Energy Matrix of Structurally Important Side-Chain/Side-Chain
Interactions in Proteins,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2010,
Volume = 6,
Number = 7,
Pages = 2191-2203,
Month = JUL,
Abstract = The interactions between amino acid side chains in proteins are
generally considered to be the most important stabilizing factor
controlling the precise arrangement of the polypeptide chain into a
well-defined spatial structure. We used the RI-DFT-D method to calculate
the full 20 x 20 matrix of interaction energies between all pairs of
amino acid side chains. For each pair, we used a representative 3D
conformation extracted from an analysis of known protein structures from
Protein Data Bank (PDB). The representative comes from the largest
cluster of relative orientations of the two side chains. We find that
all of the calculated interaction energies between selected pairs of
amino acids are attractive in the gas phase with the exception of side
chain pairs having the same total charge. We compared these data with
those calculated by the parm03 and OPLS-AA/L force fields to investigate
the reliability of simple methods in modeling biomolecules and their
behavior. The force fields yield good overall interaction energies for
our set but have problems in evaluation of some particular interactions
which could be of principal importance for protein stability. We then
looked in detail at the 20 side chain interactions involving tryptophan.
The histograms of interaction energies showed that the distributions of
the interaction energies are neither normal nor Boltzmann-like and that
our representative geometries correspond mostly to the minimum energy
geometry which is rather poorly populated in the whole pairwise energy
distribution. We concluded that cluster representatives obtained by the
clusterization algorithm based on geometry criteria cannot be considered
as a typical interaction for the whole side chain/side chain interaction
distribution. They seem to epitomize the strongest interactions in a
protein and are often functionally or structurally important.,
DOI = 10.1021/ct100007y,
ISSN = 1549-9618,
Unique-ID = ISI:000279751500026,
D. Nachtigallova, T. Zeleny, M. Ruckenbauer, T. Mueller, M. Barbatti, P. Hobza, and H. Lischka, "Does Stacking Restrain the Photodynamics of Individual Nucleobases?," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 132, iss. 24, pp. 8261+, 2010.
[Bibtex]
@article ISI:000278905700016,
Author = Nachtigallova, Dana and Zeleny, Tomas and Ruckenbauer, Matthias and
Mueller, Thomas and Barbatti, Mario and Hobza, Pavel and Lischka, Hans,
Title = Does Stacking Restrain the Photodynamics of Individual Nucleobases?,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2010,
Volume = 132,
Number = 24,
Pages = 8261+,
Month = JUN 23,
Abstract = Nonadiabatic photodynamical simulations of 4-aminopyrimidine (4-APy)
used as a model for adenine were performed by embedding it between two
stacking methyl-guanine (mGua) molecules to determine the effect of
spatial restrictions on the ultrafast photodeactivation mechanism of
this nucleobase. A hybrid multiconfigurational ab initio/molecular
mechanical approach in combination with surface hopping was used. During
the dynamics the formation of a significant fraction of intrastrand
hydrogen bonding from 4-APy to mGua above and below is observed. These
findings show that this type of hydrogen bond may play an important role
for the photodynamics within one DNA strand and that it should be of
interest even in irregular segments of double stranded nucleic acids
structures. The relaxation mechanism of internal conversion to the
ground state is dominated by ring puckering, and an overall elongation
of the lifetime of the embedded system by similar to 20\% as compared to
the isolated 4-APy is computed.,
DOI = 10.1021/ja1029705,
ISSN = 0002-7863,
Unique-ID = ISI:000278905700016,
E. Gloaguen, H. Valdes, F. Pagliarulo, R. Pollet, B. Tardivel, P. Hobza, F. Piuzzi, and M. Mons, "Experimental and Theoretical Investigation of the Aromatic-Aromatic
Interaction in Isolated Capped Dipeptides," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 114, iss. 9, pp. 2973-2982, 2010.
[Bibtex]
@article ISI:000275046600004,
Author = Gloaguen, Eric and Valdes, Haydee and Pagliarulo, Francesca and Pollet,
Rodolphe and Tardivel, Benjamin and Hobza, Pavel and Piuzzi, Francois
and Mons, Michel,
Title = Experimental and Theoretical Investigation of the Aromatic-Aromatic
Interaction in Isolated Capped Dipeptides,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2010,
Volume = 114,
Number = 9,
Pages = 2973-2982,
Month = MAR 11,
Abstract = Among the forces responsible I'm shaping proteins, interactions between
side chains of aromatic residues play all Important role I,, they are
involved in the secondary and the tertiary structures of proteins
contributing to the formation of hydrophobic domains. The purpose of
this paper is to document this interaction in two capped dipeptides
modeling a segment of a protein chain having two consecutive Phe
residues, Ac-Phe-Phe-NH(2) and Ac-Phe-D-Phe-NH(2) These two molecules
have been investigated in the gas phase by IR/UV double resonance
Spectroscopy, and the assignment of the observed conformers has been
done by comparison with quantum chemistry calculations. Both peptides
ire found to adopt it beta-turn type I conformation stabilized by
interaction between the two aromatic rings. Comparison with other
dipeptides in the literature demonstrates the Impact of fill.,,
aromatic-aromatic interaction oil the shape adopted by the peptide
chain, and its role among the Other shaping forces (H-bonds, NH-pi
interactions) is discussed As an illustration, the H-bond strength IS
found to be Significantly lower in the beta-turn type I conformer, in
which the two rings interact. as compared to (lie Similar conformer
where such all interaction does not exist this structural feature clue
to the backbone distortion induced by the interaction between the
aromatic rings makes this system a good test for evaluating the ability
Of computational methods to correctly account for the competition
between these force. MP2, SCS-MP2. DFT, and DFT-D methods have been
assessed in this respect. Comparison between geometries, energies, and
frequency calculations illustrate their respective limitations in
describing conformations resulting from a subtle equilibrium between the
several interactions at play.,
DOI = 10.1021/jp904216f,
ISSN = 1089-5639,
Unique-ID = ISI:000275046600004,
D. Svozil, P. Hobza, and J. Sponer, "Comparison of Intrinsic Stacking Energies of Ten Unique Dinucleotide
Steps in A-RNA and B-DNA Duplexes. Can We Determine Correct Order of
Stability by Quantum-Chemical Calculations? (vol 114, pg 2547, 2010)," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 114, iss. 7, pp. 2547, 2010.
[Bibtex]
@article ISI:000274578500028,
Author = Svozil, Daniel and Hobza, Pavel and Sponer, Jiri,
Title = Comparison of Intrinsic Stacking Energies of Ten Unique Dinucleotide
Steps in A-RNA and B-DNA Duplexes. Can We Determine Correct Order of
Stability by Quantum-Chemical Calculations? (vol 114, pg 2547, 2010),
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2010,
Volume = 114,
Number = 7,
Pages = 2547,
Month = FEB 25,
DOI = 10.1021/jp1004192,
ISSN = 1520-6106,
Unique-ID = ISI:000274578500028,
D. Svozil, P. Hobza, and J. Sponer, "Comparison of Intrinsic Stacking Energies of Ten Unique Dinucleotide
Steps in A-RNA and B-DNA Duplexes. Can We Determine Correct Order of
Stability by Quantum-Chemical Calculations?," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 114, iss. 2, pp. 1191-1203, 2010.
[Bibtex]
@article ISI:000273405000061,
Author = Svozil, Daniel and Hobza, Pavel and Sponer, Jiri,
Title = Comparison of Intrinsic Stacking Energies of Ten Unique Dinucleotide
Steps in A-RNA and B-DNA Duplexes. Can We Determine Correct Order of
Stability by Quantum-Chemical Calculations?,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2010,
Volume = 114,
Number = 2,
Pages = 1191-1203,
Month = JAN 21,
Abstract = High level ab initio methods have been used to study stacking
interactions in ten unique base pair steps both in A-RNA and in B-DNA
duplexes. The protocol for selection of geometries based on molecular
dynamics (MD) simulations is proposed, and its suitability is
demonstrated by comparison with stacking in steps at fiber diffraction
geometries. It is shown that fiber diffraction geometries are not
sufficiently accurate for interaction energy calculations. In addition,
the protocol for selection of geometries based on MD simulations allows
for the evaluation of the variability of the intrinsic stacking energies
along the MD trajectories. The uncertainty in stacking energies
(difference between the most and least stable geometry) due to the
dynamical nature of systems can be, in some cases, as large as 3.0 kcal
center dot mol(-1), which is almost 50\% of the actual sequence
dependence of base stacking energies (the energy difference between the
most and least stable sequences). Thus, assessing the relative magnitude
of the gas phase stacking energy using a single geometry for each
sequence is insufficient to obtain an unambiguous order of gas phase
stacking energies in canonical double helices. Though the ordering of
ten unique dinucleotide steps cannot be definitive, some general
conclusions were drawn. The stacking energies of base pair steps in
A-RNA are more evenly separated compared to B-DNA, and their ordering is
less sensitive to the dynamics of the system compared to be B-DNA. The
most stable step both in B-DNA W A-RNA is the CG/CG step that is well
separated from the second most stable step GC/GC. Also the leas/stable
step (the CC/GG step) is well separated from the rest of the structures.
The calculations further show that B-DNA stacking is favorable only
marginally (on average by 1.14 kcal center dot mol(-1) per base pair
step) over A-RNA stacking, and this difference vanishes after
subtracting the stabilizing van der Waals effect of the thymine 5-methyl
group that is absent in RNA. Basically, no correlation between the
sequence dependence of gas phase stacking energies and the sequence
dependence of Delta G degrees(37) free energies used in nearest-neighbor
models was found either for B-DNA or for A-RNA. This reflects the
complexity of the balance of forces that are responsible for the
sequence dependence of thermodynamics stability of nucleic acids, which
masks the effect of the intrinsic interactions between the stacked base
pairs.,
DOI = 10.1021/jp910788e,
ISSN = 1520-6106,
Unique-ID = ISI:000273405000061,
J. Rezac, P. Hobza, and S. A. Harris, "Stretched DNA Investigated Using Molecular-Dynamics and
Quantum-Mechanical Calculations," BIOPHYSICAL JOURNAL, vol. 98, iss. 1, pp. 101-110, 2010.
[Bibtex]
@article ISI:000273433800012,
Author = Rezac, Jan and Hobza, Pavel and Harris, Sarah A.,
Title = Stretched DNA Investigated Using Molecular-Dynamics and
Quantum-Mechanical Calculations,
Journal = BIOPHYSICAL JOURNAL,
Year = 2010,
Volume = 98,
Number = 1,
Pages = 101-110,
Month = JAN 6,
Abstract = We combined atomistic molecular-dynamics simulations with
quantum-mechanical calculations to investigate the sequence dependence
of the stretching behavior of duplex DNA. Our combined
quantum-mechanical/molecular-mechanical approach demonstrates that
molecular-mechanical force fields are able to describe both the backbone
and base-base interactions within the highly distorted nucleic acid
structures produced by stretching the DNA from the 5' ends, which
include conformations containing disassociated basepairs, just as well
as these force fields describe relaxed DNA conformations. The
molecular-dynamics simulations indicate that the force-induced melting
pathway is sequence-dependent and is influenced by the availability of
noncanonical hydrogen-bond interactions that can assist the
disassociation of the DNA basepairs. The biological implications of
these results are discussed.,
DOI = 10.1016/j.bpj.2009.08.062,
ISSN = 0006-3495,
Unique-ID = ISI:000273433800012,
M. Korth, M. Pitonak, J. Rezac, and P. Hobza, "A Transferable H-Bonding Correction for Semiempirical Quantum-Chemical
Methods," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 6, iss. 1, pp. 344-352, 2010.
[Bibtex]
@article ISI:000274757000034,
Author = Korth, Martin and Pitonak, Michal and Rezac, Jan and Hobza, Pavel,
Title = A Transferable H-Bonding Correction for Semiempirical Quantum-Chemical
Methods,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2010,
Volume = 6,
Number = 1,
Pages = 344-352,
Month = JAN,
Abstract = Semiempirical methods could offer a feasible compromise between ab
initio and empirical approaches for the calculation of large molecules
with biological relevance. A key problem for attempts in this direction
is the rather bad performance of current semiempirical methods for
noncovalent interactions, especially hydrogen-bonding. On the basis of
the recently introduced PM6-DH method, which includes, empirical
corrections for dispersion (D) and hydrogen-bond (H) interactions, we
have developed an improved and transferable H-bonding correction for
semiempirical quantum chemical methods. The performance of the improved
correction is evaluated for PM6, AM1, OM3, and SCC-DFTB (enhanced by
standard empirical dispersion corrections) with several test sets for
noncovalent interactions and is shown to reach the quality of current
DFT-D approaches for these types of problems.,
DOI = 10.1021/ct900541n,
ISSN = 1549-9618,
Unique-ID = ISI:000274757000034,
K. E. Riley, M. Pitonak, J. Cerny, and P. Hobza, "On the Structure and Geometry of Biomolecular Binding Motifs
(Hydrogen-Bonding, Stacking, X-H center dot center dot center dot pi):
WFT and DFT Calculations," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 6, iss. 1, pp. 66-80, 2010.
[Bibtex]
@article ISI:000274757000008,
Author = Riley, Kevin E. and Pitonak, Michal and Cerny, Jiri and Hobza, Pavel,
Title = On the Structure and Geometry of Biomolecular Binding Motifs
(Hydrogen-Bonding, Stacking, X-H center dot center dot center dot pi):
WFT and DFT Calculations,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2010,
Volume = 6,
Number = 1,
Pages = 66-80,
Month = JAN,
Abstract = The strengths of noncovalent interactions are generally very sensitive
to a number of geometric parameters. Among the most important of these
parameters is the separation between the interacting moieties (in the
case of an intermolecular interaction, this would be the intermolecular
separation). Most works seeking to characterize the properties of
intermolecular interactions are mainly concerned with binding energies
obtained at the potential energy minimum (as determined at some
particular level of theory). In this work, in order to extend our
understanding of these types of noncovalent interactions, we investigate
the distance dependence of several types of intermolecular interactions,
these are hydrogen bonds, stacking interactions, dispersion
interactions, and X-H center dot center dot center dot pi interactions.
There are several methods that have traditionally been used to treat
noncovalent interactions as well as many new methods that have emerged
within the past three or four years. Here we obtain reference data using
estimated CCSD(T) values at the complete basis set limit (using the
CBS(T) method); potential energy curves are also produced using several
other methods thought to be accurate for intermolecular interactions,
these are MP2/cc-pVTZ, MP2/aug-cc-pVDZ, MP2/6-31G(star)(0.25),
SCS(MI)-MP2/cc-pVTZ, estimated MP2.5/CBS, DFT-SAPT/aug-cc-pVTZ,
DFT/M06-2X/6-311+G(2df,2p), and DFT-D/TPSS/6-311++G(3df,3pd). The basis
set superposition error is systematically considered throughout the
study. It is found that the MP2.5 and DFT-SAPT methods, which are both
quite computationally intensive, produce potential energy curves that
are in very good agreement to those of the reference method. Among the
MP2 techniques, which can be said to be of medium computational expense,
the best results are obtained with MP2/cc-pVTZ and SCS(MI)-MP2/cc-pVTZ.
DFT-D/TPSS/6-311++G(3df,3pd) is the DFT-based method that can be said to
give the most well-balanced description of intermolecular interactions.,
DOI = 10.1021/ct900376r,
ISSN = 1549-9618,
Unique-ID = ISI:000274757000008,
J. Cerny and P. Hobza, "Energy barriers between H-bonded and stacked structures of
9-methyladenine center dot center dot center dot 1-methylthymine and
9-methylguanine center dot center dot center dot 1-methylcytosine
complexes," CHEMICAL COMMUNICATIONS, vol. 46, iss. 3, pp. 383-385, 2010.
[Bibtex]
@article ISI:000272992700004,
Author = Cerny, Jiri and Hobza, Pavel,
Title = Energy barriers between H-bonded and stacked structures of
9-methyladenine center dot center dot center dot 1-methylthymine and
9-methylguanine center dot center dot center dot 1-methylcytosine
complexes,
Journal = CHEMICAL COMMUNICATIONS,
Year = 2010,
Volume = 46,
Number = 3,
Pages = 383-385,
Abstract = The transition structures (TS) between H-bonded (H) and stacked (S)
structures of 9-methyladenine center dot center dot center dot
1-methylthymine and 9-methylguanine center dot center dot center dot
1-methylcytosine base pairs were localized at the DFT-D/TZVP potential
energy surface. The energy barrier between the S and TS structures is
considerably higher for the former pair than for the latter, which makes
localization of the stacked structure of this pair possible.,
DOI = 10.1039/b913209k,
ISSN = 1359-7345,
Unique-ID = ISI:000272992700004,
M. Zgarbova, M. Otyepka, J. Sponer, P. Hobza, and P. Jurecka, "Large-scale compensation of errors in pairwise-additive empirical force
fields: comparison of AMBER intermolecular terms with rigorous DFT-SAPT
calculations," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 12, iss. 35, pp. 10476-10493, 2010.
[Bibtex]
@article ISI:000281352300043,
Author = Zgarbova, Marie and Otyepka, Michal and Sponer, Jiri and Hobza, Pavel
and Jurecka, Petr,
Title = Large-scale compensation of errors in pairwise-additive empirical force
fields: comparison of AMBER intermolecular terms with rigorous DFT-SAPT
calculations,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2010,
Volume = 12,
Number = 35,
Pages = 10476-10493,
Abstract = The intermolecular interaction energy components for several molecular
complexes were calculated using force fields available in the AMBER
suite of programs and compared with Density Functional Theory-Symmetry
Adapted Perturbation Theory (DFT-SAPT) values. The extent to which such
comparison is meaningful is discussed. The comparability is shown to
depend strongly on the intermolecular distance, which means that
comparisons made at one distance only are of limited value. At large
distances the coulombic and van der Waals 1/r(6) empirical terms
correspond fairly well with the DFT-SAPT electrostatics and dispersion
terms, respectively. At the onset of electronic overlap the empirical
values deviate from the reference values considerably. However, the
errors in the force fields tend to cancel out in a systematic manner at
equilibrium distances. Thus, the overall performance of the force fields
displays errors an order of magnitude smaller than those of the
individual interaction energy components. The repulsive 1/r(12)
component of the van der Waals expression seems to be responsible for a
significant part of the deviation of the force field results from the
reference values. We suggest that further improvement of the force
fields for intermolecular interactions would require replacement of the
nonphysical 1/r(12) term by an exponential function. Dispersion
anisotropy and its effects are discussed. Our analysis is intended to
show that although comparing the empirical and non-empirical interaction
energy components is in general problematic, it might bring insights
useful for the construction of new force fields. Our results are
relevant to often performed force-field-based interaction energy
decompositions.,
DOI = 10.1039/c002656e,
ISSN = 1463-9076,
Unique-ID = ISI:000281352300043,
M. Pitonak, P. Neogrady, and P. Hobza, "Three- and four-body nonadditivities in nucleic acid tetramers: a
CCSD(T) study," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 12, iss. 6, pp. 1369-1378, 2010.
[Bibtex]
@article ISI:000274072900017,
Author = Pitonak, M. and Neogrady, P. and Hobza, P.,
Title = Three- and four-body nonadditivities in nucleic acid tetramers: a
CCSD(T) study,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2010,
Volume = 12,
Number = 6,
Pages = 1369-1378,
Abstract = Three-and four-body nonadditivities in the uracil tetramer (in DNA-like
geometry) and the GC step (in crystal geometry) were investigated at
various levels of the wave-function theory: HF, MP2, MP3, L-CCD, CCSD
and CCSD(T). All of the calculations were performed using the
6-31G**(0.25,0.15) basis set, whereas the HF, MP2 and the MP3
nonadditivities were, for the sake of comparison, also determined with
the much larger aug-cc-pVDZ basis set. The HF and MP2 levels do not
provide reliable values for many-body terms, making it necessary to go
beyond the MP2 level. The benchmark CCSD(T) three-and four-body
nonadditivities are reasonably well reproduced at the MP3 level, and
almost quantitative agreement is obtained (fortuitously) either on the
L-CCD level or as an average of the MP3 and the CCSD results. Reliable
values of many-body terms (especially their higher-order correlation
contributions) are obtained already when the rather small
6-31G**(0.25,0.15) basis set is used. The four-body term is much
smaller when compared to the three-body terms, but it is definitely not
negligible, e. g. in the case of the GC step it represents about 16\% of
all of the three-and four-body terms. While investigating the geometry
dependence of many-body terms for the GG step at the
MP3/6-31G**(0.25,0.15) level, we found that it is necessary to
include at least three-body terms in the determination of optimal
geometry parameters.,
DOI = 10.1039/b919354e,
ISSN = 1463-9076,
Unique-ID = ISI:000274072900017,
W. Zierkiewicz, D. Michalska, and P. Hobza, "Adenine ribbon stabilized by Watson-Crick and Hoogsteen hydrogen Bonds:
WFT and DFT study," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 12, iss. 12, pp. 2888-2894, 2010.
[Bibtex]
@article ISI:000275385700012,
Author = Zierkiewicz, Wiktor and Michalska, Danuta and Hobza, Pavel,
Title = Adenine ribbon stabilized by Watson-Crick and Hoogsteen hydrogen Bonds:
WFT and DFT study,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2010,
Volume = 12,
Number = 12,
Pages = 2888-2894,
Abstract = The self-organized adenine ribbon is studied theoretically. The
experimental evidence for the formation of such a ribbon has been found
in the crystal structure of the supramolecular system [Dobrzynska and
Jerzykiewicz, J. Am. Chem. Soc., 2004, 126, 11118], and the striking
structural feature is the fact that both the Watson-Crick and Hoogsteen
faces of adenine are involved in the hydrogen bonding within the ribbon.
The structure and physical properties of the monomer and five clusters
of adenine (Ade)(n) (where n = 2, 3, 4, 5, 6) with AA2(2) configuration
have been studied by means of the B3LYP, RI-TPSS, RI-TPSS-D (augmented
with the dispersion term) and RI-MP2 methods using the 6-311 + G(d,p),
cc-pVTZ and TZVP basis sets. It is shown that among the investigated
adenine clusters only the dimer has the planar structure. The evaluation
of the three-body contribution to the total binding energy of adenine
trimer has been performed at different levels of theory. All the methods
consistently indicate that this term is positive and small (less than
0.5 kcal mol(-1)) which corresponds to a weak anti-cooperative effect,
in adenine trimer. The differences between the total electronic energies
obtained at the RI-TPSS/TZVP-D and RI-TPSS/TZVP levels of theory have
shown that the London dispersion forces stabilize the adenine cluster
containing 12 or more molecules by about -8 kcal mol(-1) per molecule.
The results from the DFT symmetry adapted perturbation theory analysis
have revealed that the contribution of dispersion to the binding energy
of the adenine ribbon is about 25\%.,
DOI = 10.1039/b920433d,
ISSN = 1463-9076,
Unique-ID = ISI:000275385700012,
C. A. Morgado, P. Jurecka, D. Svozil, P. Hobza, and J. Sponer, "Reference MP2/CBS and CCSD(T) quantum-chemical calculations on stacked
adenine dimers. Comparison with DFT-D, MP2.5, SCS(MI)-MP2, M06-2X,
CBS(SCS-D) and force field descriptions," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 12, iss. 14, pp. 3522-3534, 2010.
[Bibtex]
@article ISI:000275938200021,
Author = Morgado, Claudio A. and Jurecka, Petr and Svozil, Daniel and Hobza,
Pavel and Sponer, Jiri,
Title = Reference MP2/CBS and CCSD(T) quantum-chemical calculations on stacked
adenine dimers. Comparison with DFT-D, MP2.5, SCS(MI)-MP2, M06-2X,
CBS(SCS-D) and force field descriptions,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2010,
Volume = 12,
Number = 14,
Pages = 3522-3534,
Abstract = We have performed reference quantum-chemical calculations for about 130
structures of adenine dimers in stacked conformations, with special
attention given to dimers that are either vertically compressed
(parallel structures) or contain close interatomic contacts
(non-parallel structures). Such geometries are sampled during thermal
fluctuations of nucleic acids and contribute to the local conformational
variability of these systems. Their theoretical characterization
requires a good description of interaction energies in the short-range
repulsion region. The reference calculations have been performed with
the CBS(T) method, i.e., MP2/CBS computations corrected for higher-order
electron-correlation effects using the CCSD(T) method. These benchmark
data have been used to examine the performance of the DFT-D,
SCS(MI)-MP2, MP2.5, M06-2X and CBS(SCS-D) quantum-mechanical methods,
and of the AMBER Cornell et al. force field. The present results, as
well as those of our previous study on stacked uracil dimers, confirm
that the force field severely exaggerates the repulsion at short
intermolecular distances. This behavior complicates the use of the force
field in scans of the stacking-energy dependence on local conformational
parameters in nucleic acids. Compared against the previous results
obtained in the uracil dimer study, the performance of DFT-D to describe
stacking at short intermolecular distances has worsened, showing for the
adenine dimers a larger exaggeration of the repulsion, especially for
structures where the monomers are parallel to each other. Despite these
deviations, the performance of DFT-D is still reasonably good and this
method provides, for example, a relatively inexpensive way to monitor
stacking energies along molecular dynamics trajectories. The best
performers are the MP2.5, SCS(MI)-MP2, and CBS(SCS-D) methods. In
addition, the energy profiles given by the SCS(MI)-MP2 and CBS(SCS-D)
methods are the ones that most closely resemble the CBS(T) data.
Interestingly, the performance of the SCS(MI)-MP2 method for stacked
adenine dimers is better than for stacked uracil dimers, indicating that
the quality of the description may vary with the nucleobase composition.
Even though the SCS(MI)-MP2 method cannot match the speed of DFT-D, the
results so far render it a promising tool to study intrinsic
interactions in systems of moderate size. In general, for most
applications all the QM methods tested here are of sufficient accuracy.,
DOI = 10.1039/b924461a,
ISSN = 1463-9076,
Unique-ID = ISI:000275938200021,
B. O. Crews, A. Abo-Riziq, K. Pluhackova, P. Thompson, G. Hill, P. Hobza, and M. S. de Vries, "Guanine-aspartic acid interactions probed with IR-UV resonance
spectroscopy," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 12, iss. 14, pp. 3597-3605, 2010.
[Bibtex]
@article ISI:000275938200030,
Author = Crews, Bridgit O. and Abo-Riziq, Ali and Pluhackova, Kristyna and
Thompson, Patrina and Hill, Glake and Hobza, Pavel and de Vries,
Mattanjah S.,
Title = Guanine-aspartic acid interactions probed with IR-UV resonance
spectroscopy,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2010,
Volume = 12,
Number = 14,
Pages = 3597-3605,
Abstract = Double resonance spectroscopy of clusters of guanine with aspartic acid
reveals geometries similar to patterns exhibited in DNA base pairs. In
the spectral region of 32 800 cm(-1) to 35 500 cm(-1) we observe five
isomers of guanine-aspartic acid clusters and assign their structures
based on IR-UV hole-burning spectra and wave function theory
calculations at the MP2/cc-pVDZ and MP2/cc-pVTZ levels. The calculations
employed both harmonic and one-dimensional scan anharmonic
approximations. Three of the isomers are similar, assigned to structures
containing three hydrogen bonds and 9-enolguanine. We assign the fourth
isomer to a structure containing a 9-keto tautomer of guanine and
forming a triply bonded structure similar to a base pairing interaction.
The fifth isomer dissociates with proton transfer upon excitation or
ionization. This is the first set of experiments and high-level ab
initio calculations of the isolated, microscopic interactions of an
amino acid and a nucleobase, the building blocks of nucleic acids and
proteins.,
DOI = 10.1039/b925340h,
ISSN = 1463-9076,
Unique-ID = ISI:000275938200030,
D. Nachtigallova, H. Lischka, J. J. Szymczak, M. Barbatti, P. Hobza, Z. Gengeliczki, G. Pino, M. P. Callahan, and M. S. de Vries, "The effect of C5 substitution on the photochemistry of uracil," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 12, iss. 19, pp. 4924-4933, 2010.
[Bibtex]
@article ISI:000277359300005,
Author = Nachtigallova, Dana and Lischka, Hans and Szymczak, Jaroslaw J. and
Barbatti, Mario and Hobza, Pavel and Gengeliczki, Zsolt and Pino,
Gustavo and Callahan, Michael P. and de Vries, Mattanjah S.,
Title = The effect of C5 substitution on the photochemistry of uracil,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2010,
Volume = 12,
Number = 19,
Pages = 4924-4933,
Abstract = A combined experimental and theoretical study on the excited-state
behavior of the uracil analogues, 5-OH-Ura and 5-NH(2)-Ura is reported.
Two-photon ionization and IR/UV double-resonant spectra show that there
is only one tautomer present for each with an excited state lifetime of
1.8 ns for 5-OH-Ura and 12.0 ns for 5-NH(2)-Ura as determined from
pump-probe experiments. The nature of the excited states of both species
is investigated by means of multi-reference ab initio methods. Vertical
excitation energies, excited state minima, minima on the crossing seam
and reaction paths towards them are determined. Sizeable barriers on
these paths are found that provide an explanation for the lifetimes of
several nanoseconds observed in the experiment.,
DOI = 10.1039/b925803p,
ISSN = 1463-9076,
Unique-ID = ISI:000277359300005,
Z. Gengeliczki, M. P. Callahan, N. Svadlenak, C. I. Pongor, B. Sztaray, L. Meerts, D. Nachtigallova, P. Hobza, M. Barbatti, H. Lischka, and M. S. de Vries, "Effect of substituents on the excited-state dynamics of the modified DNA
bases 2,4-diaminopyrimidine and 2,6-diaminopurine," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 12, iss. 20, pp. 5375-5388, 2010.
[Bibtex]
@article ISI:000277689500020,
Author = Gengeliczki, Zsolt and Callahan, Michael P. and Svadlenak, Nathan and
Pongor, Csaba Istvan and Sztaray, Balint and Meerts, Leo and
Nachtigallova, Dana and Hobza, Pavel and Barbatti, Mario and Lischka,
Hans and de Vries, Mattanjah S.,
Title = Effect of substituents on the excited-state dynamics of the modified DNA
bases 2,4-diaminopyrimidine and 2,6-diaminopurine,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2010,
Volume = 12,
Number = 20,
Pages = 5375-5388,
Abstract = To explore the excited state dynamics of pyrimidine derivatives, we
performed a combined experimental and theoretical study. We present
resonant two-photon ionization (R2PI) and IR-UV double resonance spectra
of 2,4-diaminopyrimidine and 2,6-diaminopurine seeded in a supersonic
jet by laser desorption. For 2,4-diaminopyrimidine (S(0) -> S(1) 34 459
cm(-1)), we observed only the diamino tautomer with an excited state
lifetime bracketed between experimental limits of 10 ps and 1 ns. For
2,6-diaminopurine, we observed two tautomers, the 9H- (S(0) -> S(1) 34
881 cm(-1)) and 7H- (S(0) -> S(1) 32 215 cm(-1)) diamino forms, with
excited state lifetimes of 6.3 +/- 0.4 ns and 8.7 +/- 0.8 ns,
respectively. We investigated the nature of the excited state of
2,4-diaminopyrimidine by means of multi-reference ab initio methods. The
calculations of stationary points in the ground and excited states,
minima on the S(0)/S(1) crossing seam and connecting reaction paths show
that several paths with negligible barriers exist, allowing ultrafast
radiationless deactivation if excited at energies slightly higher than
the band origin. The sub-nanosecond lifetime found experimentally is in
good agreement with this finding.,
DOI = 10.1039/b917852j,
ISSN = 1463-9076,
Unique-ID = ISI:000277689500020,
M. Pitonak, J. Rezac, and P. Hobza, "Spin-component scaled coupled-clusters singles and doubles optimized
towards calculation of noncovalent interactions," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 12, iss. 33, pp. 9611-9614, 2010.
[Bibtex]
@article ISI:000281007200005,
Author = Pitonak, Michal and Rezac, Jan and Hobza, Pavel,
Title = Spin-component scaled coupled-clusters singles and doubles optimized
towards calculation of noncovalent interactions,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2010,
Volume = 12,
Number = 33,
Pages = 9611-9614,
Abstract = The same- and opposite-spin scaling parameters for the SCS-CCSD method
were reparametrized on the basis of benchmark CCSD(T)/CBS set
interaction energies from the S22 set. New parameters were close to the
original ones but swap between the different spin components, being 1.11
for the opposite- and 1.28 for the same- spin component. The RMSD, and
especially, the largest error for the S22 were significantly reduced in
comparison with the original parametrization. These statistical factors
were only slightly worse when the S22x5 test set, containing not only
the equilibrium but also the non-equilibrium geometries, was used. This
new method, named the SCS(MI)-CCSD (''MI'' stands for ``Molecular
Interactions'') can thus be recommended for highly accurate
calculations of interaction energies of various noncovalent interaction
types, for which the CCSD(T)/CBS calculations are impractical.,
DOI = 10.1039/c0cp00158a,
ISSN = 1463-9076,
Unique-ID = ISI:000281007200005,
2009
P. Rezacova, J. Pokorna, J. Brynda, M. Kozisek, P. Cigler, M. Lepsik, J. Fanfrlik, J. Rezac, K. G. Saskova, I. Sieglova, J. Plesek, V. Sicha, B. Gruener, H. Oberwinkler, J. Sedlacek, H. Kraeusslich, P. Hobza, V. Kral, and J. Konvalinka, "Design of HIV Protease Inhibitors Based on Inorganic Polyhedral
Metallacarboranes," JOURNAL OF MEDICINAL CHEMISTRY, vol. 52, iss. 22, pp. 7132-7141, 2009.
[Bibtex]
@article ISI:000271825600018,
Author = Rezacova, Pavlina and Pokorna, Jana and Brynda, Jiri and Kozisek, Milan
and Cigler, Petr and Lepsik, Martin and Fanfrlik, Jindrich and Rezac,
Jan and Saskova, Klara Grantz and Sieglova, Irena and Plesek, Jaromir
and Sicha, Vaclav and Gruener, Bohumir and Oberwinkler, Heike and
Sedlacek, Juraj and Kraeusslich, Hans-Georg and Hobza, Pavel and Kral,
Vladimir and Konvalinka, Jan,
Title = Design of HIV Protease Inhibitors Based on Inorganic Polyhedral
Metallacarboranes,
Journal = JOURNAL OF MEDICINAL CHEMISTRY,
Year = 2009,
Volume = 52,
Number = 22,
Pages = 7132-7141,
Month = NOV 26,
Abstract = HIV protease (HIV PR) is a primary target for anti-HIV drug design. We
have previously identified and characterized substituted
metallacarboranes as a new class of HIV protease inhibitors. In a
structure-guided drug design effort, we connected the two cobalt
bis(dicarbollide) clusters with a linker to substituted ammonium group
and obtained a set of compounds based on a lead formula
[H(2)N-(8-(C(2)H(4)O)(2)-1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))-3,3'-
Co)(2)]Na. We explored inhibition properties of these compounds with
various substitutions, determined the HIV PR:inhibitor crystal
structure, and computationally explored the conformational space of the
linker. Our results prove the capacity of linker-substituted dual-cage
cobalt bis(dicarbollides) as lead compounds for design of more potent
inhibitors of HIV PR.,
DOI = 10.1021/jm9011388,
ISSN = 0022-2623,
Unique-ID = ISI:000271825600018,
H. Valdes, K. Pluhackova, and P. Hobza, "Phenylalanyl-Glycyl-Phenylalanine Tripeptide: A Model System for
Aromatic-Aromatic Side Chain Interactions in Proteins," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 5, iss. 9, pp. 2248-2256, 2009.
[Bibtex]
@article ISI:000269488300009,
Author = Valdes, H. and Pluhackova, K. and Hobza, P.,
Title = Phenylalanyl-Glycyl-Phenylalanine Tripeptide: A Model System for
Aromatic-Aromatic Side Chain Interactions in Proteins,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2009,
Volume = 5,
Number = 9,
Pages = 2248-2256,
Month = SEP,
Abstract = The performance of a wide range of quantum chemical calculations for the
ab initio study of realistic model systems of aromatic-aromatic side
chain interactions in proteins (in particular those pi-pi interactions
occurring between adjacent residues along the protein sequence) is here
assessed on the phenylalanyl-glycyl-phenylalanine (FGF) tripeptide.
Energies and geometries obtained at different levels of theory are
compared with CCSD(T)/CBS benchmark energies and RI-MP2/cc-pVTZ
benchmark geometries, respectively. Consequently, a protocol of
calculation alternative to the very expensive CCSD(T)/CBS is proposed.
In addition to this, the preferred orientation of the Phe aromatic side
chains is discussed and compared with previous results on the topic.,
DOI = 10.1021/ct900174f,
ISSN = 1549-9618,
Unique-ID = ISI:000269488300009,
J. Konvalinka, H. Illnerova, P. Hobza, V. Horejsi, A. Holy, P. Jungwirth, V. Paces, P. Martasek, and J. Zlatuska, "Czech bibliometric system fosters mediocre research," NATURE, vol. 460, iss. 7259, pp. 1079, 2009.
[Bibtex]
@article ISI:000269314000014,
Author = Konvalinka, Jan and Illnerova, Helena and Hobza, Pavel and Horejsi,
Vaclav and Holy, Antonin and Jungwirth, Pavel and Paces, Vaclav and
Martasek, Pavel and Zlatuska, Jiri,
Title = Czech bibliometric system fosters mediocre research,
Journal = NATURE,
Year = 2009,
Volume = 460,
Number = 7259,
Pages = 1079,
Month = AUG 27,
DOI = 10.1038/4601079c,
ISSN = 0028-0836,
Unique-ID = ISI:000269314000014,
P. Matejicek, J. Zednik, K. Uselova, J. Plestil, J. Fanfrlik, A. Nykanen, J. Ruokolainen, P. Hobza, and K. Prochazka, "Stimuli-Responsive Nanoparticles Based on Interaction of
Metallacarborane with Poly(ethylene oxide)," MACROMOLECULES, vol. 42, iss. 13, pp. 4829-4837, 2009.
[Bibtex]
@article ISI:000268138500068,
Author = Matejicek, Pavel and Zednik, Jiri and Uselova, Katerina and Plestil,
Josef and Fanfrlik, Jindrich and Nykanen, Antti and Ruokolainen, Janne
and Hobza, Pavel and Prochazka, Karel,
Title = Stimuli-Responsive Nanoparticles Based on Interaction of
Metallacarborane with Poly(ethylene oxide),
Journal = MACROMOLECULES,
Year = 2009,
Volume = 42,
Number = 13,
Pages = 4829-4837,
Month = JUL 14,
Abstract = We report the first evidence that the antiviral active (inhibitor of HIV
protease) boron cluster [3-cobalt bis(1,2-dicarbollide)](-) anion.
CoD(-), interacts and forms a stable complex with one of the most widely
used polymeric components of drug delivery systems: poly(ethylene
oxide), PEO. The metallacarborane/polymer complex is insoluble in
aqueous solutions. The amount of the precipitate depends oil
concentration of alkaline or earth-alkaline cations. The formation of
insoluble complex is the result of a combination of several Factors. One
of the decisive contributions is the formation of dihydrogen bonds
between negatively charged hydrogen atoms attached to boron atoms and
slightly positively charged H atoms in repealing -CH(2)-CH(2)-O- units.
It is also important that alkaline cations interact with oxygen atoms of
PEO. The formation of the insoluble NaCoD/PEO complex can be exploited
ill design of water-soluble [3-cobalt
bis(1,2-dicarbollide)]-containing nanoparticles which could offer
applications ill medicine. We studied the boron cluster interaction with
well-defined double hydrophilic block copolymer: poly(ethylene
oxide)-block-poly(methacrylic acid), PEO-PMA. The interaction leads to
it spontaneous formation of core-shell nanoparticles. The insoluble core
contains the PEO/CoD(-) complex, while the polyanionic PMA blocks, which
do not interact with the cobaltacarborane, form the pH-responsive
micellar shell and stabilize the particles in aqueous media. The
nanoparticles were studied by light and X-ray scattering, NMR
spectroscopy, electrophoresis, and microscopy techniques like AFM and
cryo-TEM. It was found that the cores are not completely frozen in
aqueous media. Their composition depends oil salt concentration, and the
metallacarborane call diffuse from/into the nanoparticle after the
salinity change.,
DOI = 10.1021/ma900484y,
ISSN = 0024-9297,
Unique-ID = ISI:000268138500068,
J. Rezac, J. Fanfrlik, D. Salahub, and P. Hobza, "Semiempirical Quantum Chemical PM6 Method Augmented by Dispersion and
H-Bonding Correction Terms Reliably Describes Various Types of
Noncovalent Complexes," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 5, iss. 7, pp. 1749-1760, 2009.
[Bibtex]
@article ISI:000268232500005,
Author = Rezac, Jan and Fanfrlik, Jindrich and Salahub, Dennis and Hobza, Pavel,
Title = Semiempirical Quantum Chemical PM6 Method Augmented by Dispersion and
H-Bonding Correction Terms Reliably Describes Various Types of
Noncovalent Complexes,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2009,
Volume = 5,
Number = 7,
Pages = 1749-1760,
Month = JUL,
Abstract = Because of its construction and parametrization for more than 80
elements, the semiempirical quantum chemical PM6 method is superior to
other similar methods. Despite its advantages, however, the PM6 method
fails for the description of noncovalent interactions, specifically the
dispersion energy and H-bonding. Upon inclusion of correction terms for
dispersion and H-bonding, the performance of the method was found to be
dramatically improved. The former correction included two parameters in
the damping function that were parametrized to reproduce the benchmark
interaction energies [CCSD(T)/complete basis set (CBS) limit] of the
dispersion-bonded complexes from the S22 data set. The latter correction
was parametrized on an extended set of H-bonded stabilization energies
determined at the MP2/cc-pVTZ level. The resulting PM6-DH method was
tested on the S22 data set, for which chemical accuracy (error < 1
kcal/mol) was achieved, and also on the JSCH2005 set, for which
significant improvement over the original PM6 method was also obtained.
Implementation of analytical gradients allows very efficient geometry
optimization, which, for all complexes, provides better agreement with
the benchmark data. Excellent results were also achieved for small
peptides, and here again, chemical accuracy was obtained (i.e., the
error with respect to CCSD(T)/CBS results was smaller than 1 kcal/mol).
The performance of the technique was finally demonstrated on extended
complexes, namely, the porphine dimer and various graphene models with
DNA bases and base pairs, where the PM6-DH stabilization energies agree
very well with available benchmark data obtained with DFT-D, SCS-MP2,
and MP2.5 methods. The PM6-DH calculations are very efficient and can be
routinely applied for systems of up to 1000 atoms. For nonaromatic
systems, the use of a linear scaling version of the SCF procedure based
on localized orbitals speeds up the method significantly and allows one
to investigate systems with several thousand atoms. The method can thus
replace force fields, which face basic problems for the description of
quantum effects, in many applications.,
DOI = 10.1021/ct9000922,
ISSN = 1549-9618,
Unique-ID = ISI:000268232500005,
M. Pitonak, T. Janowski, P. Neogrady, P. Pulay, and P. Hobza, "Convergence of the CCSD(T) Correction Term for the Stacked Complex
Methyl Adenine-Methyl Thymine: Comparison with Lower-Cost Alternatives," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 5, iss. 7, pp. 1761-1766, 2009.
[Bibtex]
@article ISI:000268232500006,
Author = Pitonak, M. and Janowski, T. and Neogrady, P. and Pulay, P. and Hobza,
P.,
Title = Convergence of the CCSD(T) Correction Term for the Stacked Complex
Methyl Adenine-Methyl Thymine: Comparison with Lower-Cost Alternatives,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2009,
Volume = 5,
Number = 7,
Pages = 1761-1766,
Month = JUL,
Abstract = We have performed large-scale calculations for the interaction energy of
the stacked methyl adenine-methyl thymine complex at the
CCSD(T)/aug-ccpVXZ (X = D,T) levels. The results can serve as benchmarks
for the evaluation of two methods, MP2.5, introduced recently, and the
widely used Delta CCSD(T) correction defined as the difference between
the CCSD(T) and MP2 energies. Our results confirm that the Delta CCSD(T)
correction converges much faster toward the complete basis set (CBS)
limit than toward the MP2 or CCSD(T) energies. This justifies
approximating the CBS energy by adding the Delta CCSD(T) correction
calculated with a modest basis set to a large basis MP2 energy, The fast
convergence of the Delta CCSD(T) correction is not obvious, as the
individual CCSD and (T) contributions converge less rapidly than their
sum. The MP2.5 method performs very well for this system, with results
very close to CCSD(T). It is conjectured that using a Delta MP2.5
correction, defined analogously to Delta CCSD(T), with large basis sets
may yield more reliable nonbonded interaction energies than using Delta
CCSD(T) with a smaller basis set. This would result in important
computational savings as the MP3 scales computationally much less steep
than CCSD(T), although higher than SCS-MP2, a similar approximation.,
DOI = 10.1021/ct900126q,
ISSN = 1549-9618,
Unique-ID = ISI:000268232500006,
R. Sedlak, P. Hobza, and N. G. Patwari, "Hydrogen-Bonded Complexes of Phenylacetylene with Water, Methanol,
Ammonia, and Methylamine. The Origin of Methyl Group-Induced Hydrogen
Bond Switching," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 113, iss. 24, pp. 6620-6625, 2009.
[Bibtex]
@article ISI:000266930100014,
Author = Sedlak, Robert and Hobza, Pavel and Patwari, G. Naresh,
Title = Hydrogen-Bonded Complexes of Phenylacetylene with Water, Methanol,
Ammonia, and Methylamine. The Origin of Methyl Group-Induced Hydrogen
Bond Switching,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2009,
Volume = 113,
Number = 24,
Pages = 6620-6625,
Month = JUN 18,
Abstract = The infrared spectra in the acetylenic C-H stretching region for the
complexes of phenylacetylene with water, methanol, ammonia, and
methylamine are indicative of change in the intermolecular structure
upon substitution with a methyl group. High-level ab initio calculations
at CCSD(T)/aug-cc-pVDZ level indicate that the observed complexes of
water and ammonia are energetically the most favored structures, and
electrostatics play a dominant role in stabilizing these structures. The
ability of the pi electron density of the benzene ring to offer a larger
cross-section for the interaction and the increased polarizability of
the O-H and N-H groups in methanol and methylamine favor the formation
of pi hydrogen-bonded complexes, in which dispersion is the dominant
force. Further, the observed phenylacetylene-methylamine complex can be
tentatively assigned to a kinetically trapped higher energy structure.
The observed methyl group-induced hydrogen bond switching in the
phenylacetylene complexes can be attributed to the switching of the
dominant interaction from electrostatic to dispersion.,
DOI = 10.1021/jp900813n,
ISSN = 1089-5639,
Unique-ID = ISI:000266930100014,
C. A. Morgado, P. Jurecka, D. Svozil, P. Hobza, and J. Sponer, "Balance of Attraction and Repulsion in Nucleic-Acid Base Stacking:
CCSD(T)/Complete-Basis-Set-Limit Calculations on Uracil Dimer and a
Comparison with the Force-Field Description," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 5, iss. 6, pp. 1524-1544, 2009.
[Bibtex]
@article ISI:000266865000009,
Author = Morgado, Claudio A. and Jurecka, Petr and Svozil, Daniel and Hobza,
Pavel and Sponer, Jiri,
Title = Balance of Attraction and Repulsion in Nucleic-Acid Base Stacking:
CCSD(T)/Complete-Basis-Set-Limit Calculations on Uracil Dimer and a
Comparison with the Force-Field Description,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2009,
Volume = 5,
Number = 6,
Pages = 1524-1544,
Month = JUN,
Abstract = We have carried out reference quantum-chemical calculations for about
100 geometries of the uracil dimer in stacked conformations. The
calculations have been specifically aimed at geometries with unoptimized
distances between the monomers including geometries with mutually tilted
monomers. Such geometries are characterized by a delicate balance
between local steric clashes and local unstacking and had until now not
been investigated using reference quantum-mechanics (QM) methods.
Nonparallel stacking geometries often occur in nucleic acids and are of
decisive importance, for example, for local conformational variations in
B-DNA. Errors in the short-range repulsion region would have a major
impact on potential energy scans which were often used in the past to
investigate local geometry variations in DNA. An incorrect description
of such geometries may also partially affect molecular dynamics (MD)
simulations in applications when quantitative accuracy is required. The
reference OM calculations have been carried out using the MP2 method
extrapolated to the complete basis-set limit and corrected for
higher-order electron-correlation contributions using CCSD(T)
calculations with a medium-sized basis set. These reference calculations
have been used as benchmark data to test the performance of the DFT-D,
SCS(MI)-MP2, and DFT-SAPT QM methods and of the AMBER
molecular-mechanics (MM) force field. The QM methods show close to
quantitative agreement with the reference data, albeit the DFT-D method
tends to modestly exaggerate the repulsion of steric clashes. The force
field in general also provides a good description of base stacking for
the systems studied here. However, for geometries with close interatomic
contacts and clashes, the repulsion effects are rather severely
exaggerated. The discrepancy reported here should not affect the overall
stability of MD simulations and qualitative applications of the force
field. However, it may affect the description of subtle quantitative
effects such as the local conformational variations in B-DNA.
Preliminary calculations for two H-bonded uracil base pairs, including
one with a C-H center dot center dot center dot OH-bond, indicate
excellent performance of the tested QM methods for all intermonomer
distances. The force field, on the other hand, is less satisfactory,
especially in the repulsive regions.,
DOI = 10.1021/ct9000125,
ISSN = 1549-9618,
Unique-ID = ISI:000266865000009,
J. Cerny, J. Vondrasek, and P. Hobza, "Loss of Dispersion Energy Changes the Stability and Folding/Unfolding
Equilibrium of the Trp-Cage Protein," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 113, iss. 16, pp. 5657-5660, 2009.
[Bibtex]
@article ISI:000265269100038,
Author = Cerny, Jiri and Vondrasek, Jiri and Hobza, Pavel,
Title = Loss of Dispersion Energy Changes the Stability and Folding/Unfolding
Equilibrium of the Trp-Cage Protein,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2009,
Volume = 113,
Number = 16,
Pages = 5657-5660,
Month = APR 23,
Abstract = The structure of proteins as well as their folding/unfolding equilibrium
are commonly attributed to H-bonding and hydrophobic interactions. We
have used the molecular dynamic simulations in an explicit water
environment based on the standard empirical potential as well as more
accurately (and thus also more reliably) on the QM/MM potential. The
simulations where the dispersion term was suppressed have led to a
substantial change of the tryptophan-cage protein structure (unfolded
structure). This structure cannot fold without the dispersion energy
term, whereas, if it is covered fully, the system finds its native
structure relatively quickly. This implies that after such physical
factors as temperature and pH, the dispersion energy is an important
factor in protein structure determination as well as in the protein
folding/unfolding equilibrium. The loss of dispersion also affected the
a.-helical structure. On the other hand, weakening the electrostatic
interactions (and thus H-bonding) affected the a.-helical structure only
to a minor extent.,
DOI = 10.1021/jp9004746,
ISSN = 1520-6106,
Unique-ID = ISI:000265269100038,
J. Sponer, M. Zgarbova, P. Jurecka, K. E. Riley, J. E. Sponer, and P. Hobza, "Reference Quantum Chemical Calculations on RNA Base Pairs Directly
Involving the 2 `-OH Group of Ribose," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 5, iss. 4, pp. 1166-1179, 2009.
[Bibtex]
@article ISI:000265268800057,
Author = Sponer, Jiri and Zgarbova, Marie and Jurecka, Petr and Riley, Kevin E.
and Sponer, Judit E. and Hobza, Pavel,
Title = Reference Quantum Chemical Calculations on RNA Base Pairs Directly
Involving the 2 `-OH Group of Ribose,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2009,
Volume = 5,
Number = 4,
Pages = 1166-1179,
Month = APR,
Abstract = The folded structures of RNA molecules and large ribonucleoprotein
particles are stabilized by a wide range of base pairs that actively
utilize the 2'-OH groups of ribose for base pairing. Such base pairing
does not occur in DNA and is essential for functional RNAs. We report
reference quantum chemical calculations of base pairing energies for a
representative selection of 25 RNA base pairs utilizing the ribose
moiety for base pairing, including structures with amino acceptor
interactions. All base pairs are evaluated at the MP2 level with
extrapolation to the complete basis set (CBS) of atomic orbitals.
CCSD(T) correction terms were obtained for four base pairs. In addition,
the base pairing is evaluated using the DFT-SAPT perturbational
procedure along with the aug-cc-pVDZ basis set, which allows for the
decomposition of the interaction energies into separate, physically
meaningful, components. These calculations confirm that, compared to
canonical base pairs, many RNA base pairs exhibit a modestly increased
role of dispersion attraction compared to canonical base pairs. However,
the effect is smaller than one would assume based on assessment of the
ratio of HF and correlation components of the interaction energies.
Interaction energies are further calculated using the SCS(MI)-MP2 and
DFT-D methods. Finally, we estimate the effect of aqueous solvent
screening on the base pairing stability using the continuum solvent
approach.,
DOI = 10.1021/ct800547k,
ISSN = 1549-9618,
Unique-ID = ISI:000265268800057,
J. Ran and P. Hobza, "On the Nature of Bonding in Lone Pair center dot center dot center dot
pi-Electron Complexes: CCSD(T)/Complete Basis Set Limit Calculations," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 5, iss. 4, pp. 1180-1185, 2009.
[Bibtex]
@article ISI:000265268800058,
Author = Ran, Jiong and Hobza, Pavel,
Title = On the Nature of Bonding in Lone Pair center dot center dot center dot
pi-Electron Complexes: CCSD(T)/Complete Basis Set Limit Calculations,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2009,
Volume = 5,
Number = 4,
Pages = 1180-1185,
Month = APR,
Abstract = The nature of the stabilization in lone pair center dot center dot
center dot pi-electron complexes was investigated using the highly
accurate CCSD(T) method based on the complete basis set limit, as well
as the DFT-SAPT perturabative method. Specifically, we studied various
structures of benzene center dot center dot center dot water, benzene
center dot center dot center dot dimethylether, and
1,2,4,5-tetracyanobenzene center dot center dot center dot water
complexes. The lone pair center dot center dot center dot pi-electron
interactions between an unsubstituted aromatic ring and a water molecule
are repulsive in the whole range of vertical distances. Partial
stabilization results by rotating the water molecule by 900 (with the
water and aromatic ring being localized in parallel planes) or by
decreasing the negative charge at oxygen and simultaneously increasing
the polarizability of the system, which provides stabilization even for
genuine lone pair center dot center dot center dot pi-electron
interactions. In these cases, a substantial part of the stabilization
stems from dispersion energy. Substituting an aromatic ring by
electron-withdrawing cyano groups represents the most powerful way to
achieve a substantial stabilization of genuine lone pair center dot
center dot center dot pi-electron interactions. This stabilization is
comparable to quite strong H-bonding, originating in electrostatic and,
to a slightly lesser degree, dispersion energies.,
DOI = 10.1021/ct900036y,
ISSN = 1549-9618,
Unique-ID = ISI:000265268800058,
K. Berka, R. Laskowski, K. E. Riley, P. Hobza, and J. Vondrasek, "Representative Amino Acid Side Chain Interactions in Proteins. A
Comparison of Highly Accurate Correlated ab Initio Quantum Chemical and
Empirical Potential Procedures," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 5, iss. 4, pp. 982-992, 2009.
[Bibtex]
@article ISI:000265268800037,
Author = Berka, Karel and Laskowski, Roman and Riley, Kevin E. and Hobza, Pavel
and Vondrasek, Jiri,
Title = Representative Amino Acid Side Chain Interactions in Proteins. A
Comparison of Highly Accurate Correlated ab Initio Quantum Chemical and
Empirical Potential Procedures,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2009,
Volume = 5,
Number = 4,
Pages = 982-992,
Month = APR,
Abstract = Interactions between amino acid side chains play a crucial role both
within a folded protein and between the interacting protein molecules.
Here we have selected a representative set of 24 of the 400 (20 x 20)
possible interacting side chain pairs based on data from Atlas of
Protein Side-Chain Interactions. For each pair, we obtained its most
favorable interaction geometry from the structural data and computed the
interaction energy in the gas phase using several different, commonly
used, ab initio and force field methods, namely Moller-Plesset
perturbation theory (MP2), density functional theory combined with
symmetry-adapted perturbation theory (DFT-SAPT), density functional
theory empirically augmented with an empirical dispersion term (DFT-D),
and empirical potentials using the OPLS-AA/L and Amber03 force fields.
All the methods were compared against a reference method taken to be the
CCSD(T) level of theory extrapolated to the complete basis set limit. We
found a high degree of agreement between the different methods, even
though the range of binding energies obtained was extremely large. The
most computationally intensive methods yielded the best results. Among
the less computationally time-consuming methods, the DFT-D method as
well as parm03 force field provided consistently good results when
compared to the reference values. We also tested how representative the
chosen geometries of the side chains were and investigated the effect on
the binding energies of the dielectric constant of the surrounding
medium.,
DOI = 10.1021/ct800508v,
ISSN = 1549-9618,
Unique-ID = ISI:000265268800037,
J. Ran and P. Hobza, "Nature of Bonding in Nine Planar Hydrogen-Bonded Adenine center dot
center dot center dot Thymine Base Pairs," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 113, iss. 9, pp. 2933-2936, 2009.
[Bibtex]
@article ISI:000263732700045,
Author = Ran, Jiong and Hobza, Pavel,
Title = Nature of Bonding in Nine Planar Hydrogen-Bonded Adenine center dot
center dot center dot Thymine Base Pairs,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2009,
Volume = 113,
Number = 9,
Pages = 2933-2936,
Month = MAR 5,
Abstract = In this work, we investigate the mode of binding of all nine
hydrogen-bonded structures of the adenine center dot center dot center
dot thymine base pair. The planar H-bonded structures were optimized at
the MP2/cc-pVTZ level, and the respective interaction energies,
corrected for the basis set superposition error, were determined with
the aug-cc-pVDZ basis set. The energy components were obtained from the
DFT-SAPT procedure using the aug-cc-pVDZ basis set. The charge-transfer
character of the single structures was estimated using NBO
characteristics. It was established that dipole-dipole interaction
itself cannot explain the preferred structure of the pair. Of the
various energy components, first-order electrostatic energy plays the
most important role. Second-order energy (the sum of induction and
dispersion energies) amounts to about 56\% of the electrostatic energy.
The delta(HF) term covering among others the charge-transfer energy is
rather large. The importance of delta(HF) is reflected by the NBO
characteristics and especially by the NBO charge-transfer energy. The
sum of the second-order energy and the delta(HF) term is only slightly
smaller than the electrostatic energy (75-77\%), which reflects the
importance of the nonelectrostatic terms even in the case of strong
H-bonded complexes. The WC structure, which exists in DNA, represents
the seventh local minimum, while the three most stable structures
utilize the N9-H proton donor group of the five-membered ring.,
DOI = 10.1021/jp810001v,
ISSN = 1520-6106,
Unique-ID = ISI:000263732700045,
K. Berka, P. Hobza, and J. Vondrasek, "Analysis of Energy Stabilization inside the Hydrophobic Core of
Rubredoxin," CHEMPHYSCHEM, vol. 10, iss. 3, pp. 543-548, 2009.
[Bibtex]
@article ISI:000264229900014,
Author = Berka, Karel and Hobza, Pavel and Vondrasek, Jiri,
Title = Analysis of Energy Stabilization inside the Hydrophobic Core of
Rubredoxin,
Journal = CHEMPHYSCHEM,
Year = 2009,
Volume = 10,
Number = 3,
Pages = 543-548,
Month = FEB 23,
Abstract = The hydrophobic core of globular proteins is responsible for major
stabilization of the protein tertiary structure. The prevailing amino
acid residues in the core are of aliphatic or aromatic character and
therefore the core in a folded protein structure is mostly stabilized by
noncovalent interactions of van der Waals origin between the amino acid
side chains. Herein, we present a theoretical analysis of the
interaction energy between the amino acids of the hydrophobic core of
the small globular protein rubredoxin (Rd) based on the symmetry-adapted
perturbation theory (SAPT) method. The results show uniform proportions
between the second-order dispersion and first-order electrostatic energy
terms in favor of dispersion interaction which plays a major role in the
stabilization of this important structural element. To demonstrate the
contrast between systems stabilized by different mechanisms, we perform
a SAPT analysis of the typical hydrogen bonds involved in the formation
of protein secondary structure elements in Rd, where dispersion still
plays a non-negligible role but electrostatic energy is the major
stabilizing factor.,
DOI = 10.1002/cphc.200800401,
ISSN = 1439-4235,
Unique-ID = ISI:000264229900014,
M. Pitonak, P. Neogrady, J. Cerny, S. Grimme, and P. Hobza, "Scaled MP3 Non-Covalent Interaction Energies Agree Closely with Accurate
CCSD(T) Benchmark Data," CHEMPHYSCHEM, vol. 10, iss. 1, pp. 282-289, 2009.
[Bibtex]
@article ISI:000262870500038,
Author = Pitonak, Michal and Neogrady, Pavel and Cerny, Jiri and Grimme, Stefan
and Hobza, Pavel,
Title = Scaled MP3 Non-Covalent Interaction Energies Agree Closely with Accurate
CCSD(T) Benchmark Data,
Journal = CHEMPHYSCHEM,
Year = 2009,
Volume = 10,
Number = 1,
Pages = 282-289,
Month = JAN 12,
Abstract = Scaled MP3 interaction energies calculated as a sum of MP2/CBS (complete
basis set limit) interaction energies and scaled third-order energy
contributions obtained in small or medium size basis sets agree very
closely with the estimated CCSD(T)/CBS interaction energies for the 22
H-bonded, dispersion-controlled and mixed non-covalent complexes from
the S22 data set. Performance of this so-called MP2.5 (third-order
scaling factor of 0.5) method has also been tested for 33 nucleic acid
base pairs and two stacked conformers of porphine dimer. In all the test
cases, performance of the MP2.5 method was shown to be superior to the
scaled spin-component MP2 based methods, e.g. SCS-MP2, SCSN-MP2 and
SCS(MI)-MP2. In particular, a very balanced treatment of hydrogen-bonded
compared to stacked complexes is achieved with MP2.5. The main advantage
of the approach is that it employs only a single empirical parameter and
is thus biased by two rigorously defined, asymptotically correct
ob-initio methods, MP2 and MP3. The method is proposed as an accurate
but computationally feasible alternative to CCSD(T) for the computation
of the properties of various kinds of non-covalently bound systems.,
DOI = 10.1002/cphc.200800718,
ISSN = 1439-4235,
Unique-ID = ISI:000262870500038,
K. E. Riley, J. S. Murray, P. Politzer, M. C. Concha, and P. Hobza, "Br center dot center dot center dot O Complexes as Probes of Factors
Affecting Halogen Bonding: Interactions of Bromobenzenes and
Bromopyrimidines with Acetone," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 5, iss. 1, pp. 155-163, 2009.
[Bibtex]
@article ISI:000262432000016,
Author = Riley, Kevin E. and Murray, Jane S. and Politzer, Peter and Concha,
Monica C. and Hobza, Pavel,
Title = Br center dot center dot center dot O Complexes as Probes of Factors
Affecting Halogen Bonding: Interactions of Bromobenzenes and
Bromopyrimidines with Acetone,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2009,
Volume = 5,
Number = 1,
Pages = 155-163,
Month = JAN,
Abstract = Halogen bonding is a unique type of noncovalent binding phenomenon in
which a halogen atom interacts attractively with an electronegative atom
such as oxygen or nitrogen. These types of interactions have been the
subject of many recent investigations because of their potential in the
development of new materials and pharmaceutical compounds. Recently, it
was observed that most halogen bonding interactions in biological
contexts involve close contacts between a halogen bound to an aromatic
ring and a carbonyl oxygen on a protein's backbone structure. In this
work we investigate interactions of substituted bromobenzenes and
bromopyrimidines with acetone to ascertain the effects of various
substituents; upon the strengths of these interactions. It was found
that replacement of ring hydrogens in these systems has dramatic effects
upon the interaction strengths of the resulting complexes, which have
interaction energies between -1.80 and -7.11 kcal/mol. Examination of
the electrostatic potentials of the substituted bromobenzene and
bromopyrimidine monomers indicates that the addition of substituents has
a large influence upon the most positive electrostatic potential on the
surface of the interacting bromine and thus modulates these halogen
bonding interactions. Results obtained using the symmetry-adapted
perturbation theory (SAPT) interaction energy decomposition procedure
also indicate that electrostatic interactions play the key role in these
halogen bonding interactions. These results have important implications
in drug design and crystal engineering. Halogen bonds have been a
subject of great interest in these fields because of their unique
noncovalent bonding characteristics.,
DOI = 10.1021/ct8004134,
ISSN = 1549-9618,
Unique-ID = ISI:000262432000016,
L. Zendlova, D. Reha, M. Hocek, and P. Hobza, "Theoretical Study of the Stability of the DNA Duplexes Modified by a
Series of Hydrophobic Base Analogues," CHEMISTRY-A EUROPEAN JOURNAL, vol. 15, iss. 31, pp. 7601-7610, 2009.
[Bibtex]
@article ISI:000268845000013,
Author = Zendlova, Lucie and Reha, David and Hocek, Michal and Hobza, Pavel,
Title = Theoretical Study of the Stability of the DNA Duplexes Modified by a
Series of Hydrophobic Base Analogues,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2009,
Volume = 15,
Number = 31,
Pages = 7601-7610,
Abstract = The geometries of a 13 mer of a DNA double helix (5'-GCGTA-CACATGCG-3')
were determined by molecular dynamics simulations using a Cornell et al.
empirical force field. ne bases in the central base pair (shown in bold)
were replaced (one or both) by a series of hydrophobic base analogues
(phenyl, biphenyl, phenylnaphathalene, phenylanthracene and
phenylphenanthrene). Due to the large fluctuations of the systems, an
average geometry could not be determined. The interaction energies of
the Model A, which consisted of three central steps of a duplex without
a sugar phosphate backbone, taken from molecular dynamics simulations
(geometry sampled every 1 ps), were calculated by the self-consistent
charge density functional based tight-binding (SCC-DFTB-D) method and
were subsequently averaged. The higher the stability of the systems the
higher the aromaticity of the base analogues. To estimate the
desolvation energy of the duplex, the COSMO continuum solvent model was
used and the calculations were provided on a larger model, Model B (the
three central steps of the duplex with a sugar phosphate backbone
neutralised by H atoms), taken from molecular dynamics simulations
(geometry sampled every 200 ps) and subsequently averaged. The
selectivity of the base analogue pairs was ascertained (Model 13) by
including the desolvation energy and the interaction energy of both
strands, as determined by the SCC-DFTB-D method. The highest selectivity
was found for a phenylphenanthrene. Replacing the nucleic acid bases
with a base analogue leads to structural changes of the central pair.
Only with the smallest base analogues (phenyl) does the central base
pair stay planar. When passing to larger base analogues the central base
pair is usually stacked.,
DOI = 10.1002/chem.200802170,
ISSN = 0947-6539,
Unique-ID = ISI:000268845000013,
T. Zeleny, P. Hobza, and M. Kabelac, "Microhydration of guanine center dot center dot center dot cytosine base
pairs, a theoretical Study on the role of water in stability, structure
and tautomeric equilibrium," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 11, iss. 18, pp. 3430-3435, 2009.
[Bibtex]
@article ISI:000265413300010,
Author = Zeleny, Tomas and Hobza, Pavel and Kabelac, Martin,
Title = Microhydration of guanine center dot center dot center dot cytosine base
pairs, a theoretical Study on the role of water in stability, structure
and tautomeric equilibrium,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2009,
Volume = 11,
Number = 18,
Pages = 3430-3435,
Abstract = The potential energy surfaces of guanine center dot center dot center
dot cytosine complexes and microhydrated guanine center dot center dot
center dot cytosine (one and two water molecules) were investigated by
the molecular dynamics/quenching method (MD/Q), using the empirical
potential Parm94 force field, implemented in the Amber program package.
The calculations were conducted for all the possible combinations of the
four most stable tautomers of guanine and three of cytosine (covering
the canonical forms in both cases). The obtained structures were sorted
by their structural motifs into three main groups: planar
hydrogen-bonded; stacked; and T-shaped structures. The most stable
structures found at the empirical potential energy surfaces were fully
reoptimised at the second-order Moller-Plesset perturbation theory as
well as using the density functional method with an empirical dispersion
term (DFT-D). A combination of the canonical form of guanine and
cytosine and canonical cytosine with a guanine tautomer where the
hydrogen is switched from position N9 to N7 are energetically preferred
in microsolvated systems as well as those without the presence of a
solvent. The rising number of water molecules leads to smaller
differences between the stability of the various combinations of the
tautomers of bases in the base pairs. For some of the tautomer
combinations (mainly the enol-enol combination), two water molecules are
sufficient for the preference of stacked structures over the H-bonded
ones. The interaction energies and geometries obtained by the
second-order Moller-Plesset perturbation theory method and the much less
computationally demanding DFT-D method are comparable, except for
stacked complexes, where the interaction energies are overestimated on
average by 3 kcal mol(-1) at the MP2 level.,
DOI = 10.1039/b819350a,
ISSN = 1463-9076,
Unique-ID = ISI:000265413300010,
M. Kabelac, P. Hobza, and V. Spirko, "The structure and vibrational dynamics of the pyrrole dimmer," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 11, iss. 20, pp. 3885-3891, 2009.
[Bibtex]
@article ISI:000266065400010,
Author = Kabelac, Martin and Hobza, Pavel and Spirko, Vladimir,
Title = The structure and vibrational dynamics of the pyrrole dimmer,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2009,
Volume = 11,
Number = 20,
Pages = 3885-3891,
Abstract = The energy, dynamical geometry characteristics and low frequency
intermolecular vibrations of the pyrrole dimer have been examined at the
MP2 and CCSD(T) levels of ab initio theory. The actual distortions of
the pyrrole dimer from its reference (equilibrium) position were
measured using the distance of the monomer mass centres (R), the angle
between their planes (the mirror planes orthogonal to the molecular
planes of both monomers were assumed to coincide) and the angle between
the R directional vector and the proton-accepting monomer plane; the
structures of the monomers were assumed to be unchanged by dimerisation.
The lowest part of the potential energy function confining the probed
motions possessed two equivalent energy pockets with the
CCSD(T)/complete basis set limit stabilisation energy of 6.2 kcal
mol(-1) separated by a relatively low barrier (0.8 kcal mol(-1)), thus
raising questions concerning the classical interconversion of the
T-shaped equilibrium structures via a C(2h) parallel-displaced transient
structure and/or quantum mechanical tunnellings through the barrier. The
questions have been answered unequivocally by calculating the energies
and tunnelling splittings of the relevant vibrational levels.
Importantly: (a) all the excited tunnelling (interconverting) states
underwent fast geometry interconversions, hence evidencing
conformational instability of the studied dimer under usual laboratory
conditions; (b) the dynamical averages of the used geometry
characteristics exhibited profound tunnelling (interconverting)
dependences, thus advocating that they be respected in reliable
structural studies of the pyrrole dimer and chemically similar systems;
(c) the geometry characteristics of the ground vibrational state agreed
quite reasonably with their experimental counterparts, evidencing the
adequacy of the theory used and the reliability of the characteristics
predicted for the excited vibrational states; and (d) the calculated
dissociation barrier of the dimer exceeds its experimentally derived
analogue by more than three times, showing the inadequacy of the
constraining assumptions used to derive it from the experimental
spectra.,
DOI = 10.1039/b822764k,
ISSN = 1463-9076,
Unique-ID = ISI:000266065400010,
M. Kabelac, P. Hobza, and V. Spirko, "The ab initio assigning of the vibrational probing modes of tryptophan:
linear shifting of approximate anharmonic frequencies vs. multiplicative
scaling of harmonic frequencies," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 11, iss. 20, pp. 3921-3926, 2009.
[Bibtex]
@article ISI:000266065400014,
Author = Kabelac, Martin and Hobza, Pavel and Spirko, Vladimir,
Title = The ab initio assigning of the vibrational probing modes of tryptophan:
linear shifting of approximate anharmonic frequencies vs. multiplicative
scaling of harmonic frequencies,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2009,
Volume = 11,
Number = 20,
Pages = 3921-3926,
Abstract = To gain insight into the prospects for a few-dimensional ab initio
quantum-mechanical description of the vibrational motions of
conformationally flexible molecular systems, the NH-, NH(2)-, CO- and
OH-stretching and COH-bending vibrations of the most stable tryptophan
conformations have been probed using simple one- and two-dimensional
anharmonic Hamiltonians and potential energy functions evaluated by
means of the standard RI-MP2, CCSD(T) and DFT-D quantum chemical
procedures. Although strongly dependent on the procedure used, the
calculated vibrational spectral patterns have been found to be in a
robust one-to-one harmony with their experimental counterparts, thus
proving the adequacy of the theory used for the reliable assignment of
the experimental data. Therefore, the approach appears to be a suitable
tool for assigning the vibrational probing modes even of systems which
are too large to be tractable by the standard normal-coordinate
analysis.,
DOI = 10.1039/b823373j,
ISSN = 1463-9076,
Unique-ID = ISI:000266065400014,
S. Maity, R. Sedlak, P. Hobza, and N. G. Patwari, "Infrared-optical double resonance spectroscopic measurements and high
level ab initio calculations on a binary complex between phenylacetylene
and borane-trimethylamine. Understanding the role of C-H center dot
center dot center dot pi interactions," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 11, iss. 42, pp. 9738-9743, 2009.
[Bibtex]
@article ISI:000271033200015,
Author = Maity, Surajit and Sedlak, Robert and Hobza, Pavel and Patwari, G.
Naresh,
Title = Infrared-optical double resonance spectroscopic measurements and high
level ab initio calculations on a binary complex between phenylacetylene
and borane-trimethylamine. Understanding the role of C-H center dot
center dot center dot pi interactions,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2009,
Volume = 11,
Number = 42,
Pages = 9738-9743,
Abstract = The structure of the binary complex between phenylacetylene and
borane-trimethylamine has been elucidated using IR-UV double resonance
spectroscopy in combination with high level ab initio calculations at
the CCSD(T) level. Borane-trimethylamine interacts primarily through
multiple C-H center dot center dot center dot pi interactions with the p
electron density of the benzene ring in phenylacetylene. CCSD(T) level
calculations provide reliable estimates for the interaction energy and
free energy, which are in accord with the experimental observations. The
DFT-SAPT calculations point out that the dispersion interaction plays a
major role in the formation of the experimentally observed complex,
along with a sizable contribution from electrostatics.,
DOI = 10.1039/b911926d,
ISSN = 1463-9076,
Unique-ID = ISI:000271033200015,
2008
W. Zierkiewicz, L. Komorowski, D. Michalska, J. Cerny, and P. Hobza, "The Amino Group in Adenine: MP2 and CCSD(T) Complete Basis Set Limit
Calculations of the Planarization Barrier and DFT/B3LYP Study of the
Anharmonic Frequencies of Adenine," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 112, iss. 51, pp. 16734-16740, 2008.
[Bibtex]
@article ISI:000261835100062,
Author = Zierkiewicz, Wiktor and Komorowski, Ludwik and Michalska, Danuta and
Cerny, Jiri and Hobza, Pavel,
Title = The Amino Group in Adenine: MP2 and CCSD(T) Complete Basis Set Limit
Calculations of the Planarization Barrier and DFT/B3LYP Study of the
Anharmonic Frequencies of Adenine,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2008,
Volume = 112,
Number = 51,
Pages = 16734-16740,
Month = DEC 25,
Abstract = The amino group in adenine plays a key role in formation of hydrogen
bonds in nucleic acids and in other molecular systems. Thus, the
structure of this group is of fundamental importance in the molecular
recognition phenomena. Ab initio MP2 and density functional B3LYP
methods with various basis sets have been used to calculate the
optimized structure and the infrared spectrum of adenine (the N9-H
tautomer). Calculations at the MP2 level with larger basis sets tend to
decrease the degree of pyramidalization of the C-NH(2) group, whereas
the B3LYP method consistently yields the planar or nearly planar
structure of adenine. MP2 complete basis set (CBS) limit method with the
aug-cc-pVTZ -> aug-cc-pVQZ (aTZ -> aQZ) extrapolation scheme has
predicted very small planarization barrier of adenine, 0.015 kcal/mol,
which is in very good agreement with the MP2-predicted planarization
barrier of 0.020 kcal/mol, reported by S. Wang and H. F. Schaefer III,
J. Chem. Phys. 2006, 124, 044303. Similar results were obtained in
calculations by the coupled cluster CCSD(T) CBS method. Thus, it can be
concluded that the amino group in adenine, in the gas phase, is very
flexible with a small degree of nonplanarity. Extremely low
planarization barrier implies that adenine requires very little energy
to conform the structure of the amino group to formation of the
complementary hydrogen bonds with other molecules. This fact is very
important for base pairing in nucleic acids or other polymers containing
adenine residues. The anharmonic frequencies of adenine have been
calculated at the B3LYP/6-311++G(df, pd) level of theory. The
theoretical results show excellent agreement with the available
experimental data. The revised assignment of the infrared spectrum of
adenine in Ar matrix has been made. The predicted anharmonic frequency
of the NH(2) inversion, 181 cm(-1), is supported by the experimental
data. It is demonstrated that the vibrational frequencies and potential
energy distribution (PED) obtained from the B3LYP calculations are more
reliable than those obtained at the MP2 level.,
DOI = 10.1021/jp8058118,
ISSN = 1520-6106,
Unique-ID = ISI:000261835100062,
K. Pluhackova, S. Grimme, and P. Hobza, "On the Importance of Electron Correlation Effects for the Intramolecular
Stacking Geometry of a Bis-Thiophene Derivative," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 112, iss. 48, pp. 12469-12474, 2008.
[Bibtex]
@article ISI:000261218100023,
Author = Pluhackova, Kristyna and Grimme, Stefan and Hobza, Pavel,
Title = On the Importance of Electron Correlation Effects for the Intramolecular
Stacking Geometry of a Bis-Thiophene Derivative,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2008,
Volume = 112,
Number = 48,
Pages = 12469-12474,
Month = DEC 4,
Abstract = The structure of dithienobicyclo[4.4.1]undeca-3,8-diene-11-one
ethylene glycol ketal (database code RESVAN) was determined using the
wave function theory (WFT) as well as density functional theory (DFT)
methods combined with various Gaussian AO basis sets. The apparently
most accurate procedure, employing the CCSD(T)/complete basis set (CBS),
provides an S-S distance and an angle between the two thiophene rings
which differ considerably from experimental values. The best agreement
with the experimental data among, all WFT methods was surprisingly
obtained at the MP3/aug-cc-pVDZ and MP3/CBS(B) levels (the correction
term to CBS was obtained by the aug-cc-pVDZ basis set). The very good
results obtained by the CCSD(T)/6-31G* method are clearly a
consequence of fortunate error compensation. MP2 calculations, even with
a small basis set, overestimate the attraction between the thiophene
rings, and the worst agreement with experimental data was found in full
MP2/QZVP method optimizations (i.e., a strong distortion of the
thiophene rings was observed). The SCS(MI)-MP2 and SCS-MP2 methods
exhibit improvement over the MP2 procedure. All standard DFT approaches
fail to predict reasonable S-S distances. The lack of intramolecular
London dispersion energy results in too great distance between the
thiophene rings. Much better agreement with experiment was obtained if
advanced DFT methods, covering dispersion effects, were used. The best
results were obtained at the TPSS-D/TZVP, M06-L/TZVP and
B2PLYP-D/def2-TZVP levels. When a larger basis (LP in the case of TPSS
functional) or more advanced versions of the new Truhlar functionals
(M06-2X) was used, the agreement with experiment deteriorated. The
accurate description of this molecule is highly functional/basis
dependent and this dependence is hardly predictable. To estimate effects
of neighboring molecules in the experimental crystal structure, an
optimization in the electric field of the 26 closest RESVAN molecules
was performed, which, however, leads to only moderate (<0.05 angstrom)
changes of the S-S distance.,
DOI = 10.1021/jp8051664,
ISSN = 1089-5639,
Unique-ID = ISI:000261218100023,
J. Fanfrlik, J. Brynda, J. Rezac, P. Hobza, and M. Lepsik, "Interpretation of Protein/Ligand Crystal Structure using QM/MM
Calculations: Case of HIV-1 Protease/Metallacarborane Complex," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 112, iss. 47, pp. 15094-15102, 2008.
[Bibtex]
@article ISI:000261056400050,
Author = Fanfrlik, Jindrich and Brynda, Jiri and Rezac, Jan and Hobza, Pavel and
Lepsik, Martin,
Title = Interpretation of Protein/Ligand Crystal Structure using QM/MM
Calculations: Case of HIV-1 Protease/Metallacarborane Complex,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2008,
Volume = 112,
Number = 47,
Pages = 15094-15102,
Month = NOV 27,
Abstract = Deltahedral metallacarborane compounds have recently been discovered as
potent, specific, stable, and nontoxic inhibitors of HIV-1 protease
(PR), the major target for AIDS therapy. The 2.15 angstrom-resolution
X-ray structure has exhibited a nonsymmetrical binding of the parental
compound [Co(3+)-(C(2)B(9)H(11))(2)](-) (GB-18) into PR dimer and a
symmetrical arrangement in the crystal of two PR dimer complexes into a
tetramer. In order to explore structural and energetic details of the
inhibitor binding, quantum mechanics coupled with molecular mechanics
approach was utilized. Realizing the close positioning of anionic
inhibitors in the active site cavity, the possibility of an exchange of
structural water molecules Wat50 and Wat128 by Na(+) counterions was
studied. The energy profiles for the rotation of the GB - 18 molecules
along their longitudinal axes in complex with PR were calculated. The
results show that two Na(+) counterions are present in the active site
cavity and provide energetically favorable and unfavorable positions for
carbon atoms within the carborane cages. Eighty-one rotamer combinations
of four molecules of GB-18 bound to PR out of 4 x 10(5) are predicted to
be highly populated. These results lay ground for further calculations
of interaction energies between GB - 18 and amino acids of PR active
site and will make it possible to interpret computationally the binding
of similar metallacarborane molecules to PR as well as to resistant PR
variants. Moreover, this computational tool will allow the design of
new, more potent metallacarborane-based HIV-1 protease inhibitors.,
DOI = 10.1021/jp803528w,
ISSN = 1520-6106,
Unique-ID = ISI:000261056400050,
J. Cerny, M. Kabelac, and P. Hobza, "Double-Helical -> Ladder Structural Transition in the B-DNA is Induced
by a Loss of Dispersion Energy," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 130, iss. 47, pp. 16055-16059, 2008.
[Bibtex]
@article ISI:000263319600064,
Author = Cerny, Jiri and Kabelac, Martin and Hobza, Pavel,
Title = Double-Helical -> Ladder Structural Transition in the B-DNA is Induced
by a Loss of Dispersion Energy,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2008,
Volume = 130,
Number = 47,
Pages = 16055-16059,
Month = NOV 26,
Abstract = The role of the dispersion energy and electrostatic energy on the
geometry and stability of the B-DNA helix was investigated. Both
molecular dynamics simulations with empirical force field and hybrid
quantum mechanical/molecular mechanics molecular dynamics simulations,
where the dispersion or electrostatics term is suppressed/increased, on
the one hand and an ab initio minimization procedure on the other have
shown that the lack of the dispersion term leads to an increase of the
vertical separation of the bases as well as to a loss of helicity, thus
resulting in a ladder-like structure. A decrease of the electrostatic
term produces a separation of the DNA strands. The biological
consequences of both electrostatic and dispersion forces in DNA are
enormous, and without either of them, DNA would become unstable and
unable to, provide the storage and transfer of genetic information.,
DOI = 10.1021/ja805428q,
ISSN = 0002-7863,
Unique-ID = ISI:000263319600064,
M. Pitonak, P. Neogrady, J. Rezac, P. Jurecka, M. Urban, and P. Hobza, "Benzene Dimer: High-Level Wave Function and Density Functional Theory
Calculations," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 4, iss. 11, pp. 1829-1834, 2008.
[Bibtex]
@article ISI:000260851300003,
Author = Pitonak, M. and Neogrady, P. and Rezac, J. and Jurecka, P. and Urban, M.
and Hobza, P.,
Title = Benzene Dimer: High-Level Wave Function and Density Functional Theory
Calculations,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2008,
Volume = 4,
Number = 11,
Pages = 1829-1834,
Month = NOV,
Abstract = High-level OVOS (optimized virtual orbital space) CCSD(T) interaction
energy calculations (up to the aug-cc-pVQZ basis set) and various
extrapolations toward the complete basis set (CBS) limit are presented
for the most important structures on the benzene dimer potential energy
surface. The geometries of these structures were obtained via an
all-coordinate gradient geometry optimization using the DFT-D/BLYP
method, covering the empirical dispersion correction fitted exclusively
for this system. The fit was carried out against two estimated
CCSD(T)/CBS potential energy curves corresponding to the distance
variation between two benzene rings for the parallel-displaced (PD) and
T-shaped (T) structures. The effect of the connected quadruple
excitations on the interaction energy was estimated using the
CCSD(TQ(f)) method in a 6-31 G*(0.25) basis set, destabilizing the T
and T-shaped tilted (TT) structures by approximate to 0.02 kcal/mol and
the PD structure by approximate to 0.04 kcal/mol. Our best CCSD(T)/CBS
results show, within the error bars of the applied methodology, that the
energetically lowest-lying structure is the TT structure, which is
nearly 0.1 kcal/mol more stable than the almost isoenergetic PD and T
structures. The specifically parametrized DFT-D/BLYP method leads to a
correct energy ordering of the structures, with the errors being smaller
by 0.2 kcal/mol with respect to the most accurate CCSD(T) values.,
DOI = 10.1021/ct800229h,
ISSN = 1549-9618,
Unique-ID = ISI:000260851300003,
J. Rezac and P. Hobza, "Benzene Dimer: Dynamic Structure and Thermodynamics Derived from
On-the-Fly ab initio DFT-D Molecular Dynamic Simulations," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 4, iss. 11, pp. 1835-1840, 2008.
[Bibtex]
@article ISI:000260851300004,
Author = Rezac, Jan and Hobza, Pavel,
Title = Benzene Dimer: Dynamic Structure and Thermodynamics Derived from
On-the-Fly ab initio DFT-D Molecular Dynamic Simulations,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2008,
Volume = 4,
Number = 11,
Pages = 1835-1840,
Month = NOV,
Abstract = The dynamic nature of the benzene dimer was explored by on-the-fly
molecular dynamics simulations based on the DFT-D method covering the
dispersion energy. An all-electron DFT was performed at the BLYP/TZVP
level. The parameters in the dispersion correction term were fitted to
mimic the benchmark CCSD(T)/complete basis set limit potential energy
curves for both the parallel-displaced (PD) and T-shaped (TS) structures
of the dimer exactly. A dynamic description is important at temperatures
above 10 K, where interconversion between the TS and PD structures is
possible and a mixture of these two species exists. The higher the
temperature, the more dominant the TS structure because of a favorable
entropic contribution to the free energy. An analysis of the TS
structures revealed that the symmetric C-2v structure, a low-lying
transition state, is practically not populated and that the tilted C-s
TS structure is prevalent. This finding is in perfect agreement with
infrared spectroscopy.,
DOI = 10.1021/ct8002282,
ISSN = 1549-9618,
Unique-ID = ISI:000260851300004,
M. Pitonak, K. E. Riley, P. Neogrady, and P. Hobza, "Highly accurate CCSD(T) and DFT-SAPT stabilization energies of H-bonded
and stacked structures of the uracil dimer," CHEMPHYSCHEM, vol. 9, iss. 11, pp. 1636-1644, 2008.
[Bibtex]
@article ISI:000258368700022,
Author = Pitonak, Michal and Riley, Kevin E. and Neogrady, Pavel and Hobza, Pavel,
Title = Highly accurate CCSD(T) and DFT-SAPT stabilization energies of H-bonded
and stacked structures of the uracil dimer,
Journal = CHEMPHYSCHEM,
Year = 2008,
Volume = 9,
Number = 11,
Pages = 1636-1644,
Month = AUG 4,
Abstract = The CCSD(T) interaction energies for the H-bonded and Stacked structures
of the uracil dimer are determined at the aug-cc-pVDZ and aug-cc-pVTZ
levels. On the basis of these calculations we can construct the CCSD(T)
interaction energies at the complete basis set (CBS) limit. The most
accurate energies, based either on direct extrapolation of the CCSD(T)
correlation energies obtained with the aug-cc-pVDZ and aug-cc-pVTZ basis
sets or on the sum of extrapolated MP2 interaction energies (from
aug-cc-pVTZ and aug-cc-pVQZ basis sets) and extrapolated Delta CCSD(T)
correction terms [difference between CCSD(T) and MP2 interaction
energies] differ only slightly, which demonstrates the reliability and
robustness of both techniques. The latter values, which represent new
standards for the H-bonding and stacking structures of the uracil dimer,
differ from the previously published data for the S22 set by a small
amount. This suggests that interaction energies of the S22 set are
generated with chemical accuracy. The most accurate CCSD(T)/CBS
interaction energies are compared with interaction energies obtained
from various computational procedures, namely the SCS-MP2 (SCS:
spin-component-scaled), SCS(MI)-MP2 (MI: molecular interaction), MP3,
dispersion-augmented DFT (DFT-D), M06-2X, and DFT-SAPT (SAPT.
symmetry-adapted perturbation theory) methods. Among these techniques,
the best results are obtained with the SCS(MI)-MP2 method. Remarkably
good binding energies are also obtained with the DFT-SAPT method. Both
DFT techniques tested yield similarly good interaction energies. The
large magnitude of the stacking energy for the uracil dimer, compared to
that of the benzene dimer is explained by attractive electrostatic
interactions present in the stacked uracil dimer. These interactions
force both subsystems to approach each other and the dispersion energy
benefits from a shorter intersystem separation.,
DOI = 10.1002/cphc.200800286,
ISSN = 1439-4235,
Unique-ID = ISI:000258368700022,
J. S. Murray, M. C. Concha, P. Lane, P. Hobza, and P. Politzer, "Blue shifts vs red shifts in sigma-hole bonding," JOURNAL OF MOLECULAR MODELING, vol. 14, iss. 8, pp. 699-704, 2008.
[Bibtex]
@article ISI:000257330700007,
Author = Murray, Jane S. and Concha, Monica C. and Lane, Pat and Hobza, Pavel and
Politzer, Peter,
Title = Blue shifts vs red shifts in sigma-hole bonding,
Journal = JOURNAL OF MOLECULAR MODELING,
Year = 2008,
Volume = 14,
Number = 8,
Pages = 699-704,
Month = AUG,
Abstract = sigma-Hole bonding is a noncovalent interaction between a region of
positive electrostatic potential on the outer surface of a Group V, VI,
or VII covalently-bonded atom (a sigma-hole) and a region of negative
potential on another molecule, e.g., a lone pair of a Lewis base. We
have investigated computationally the occurrence of increased vibration
frequencies (blue shifts) and bond shortening vs decreased frequencies
(red shifts) and bond lengthening for the covalent bonds to the atoms
having the sigma-holes (the sigma-hole donors). Both are possible,
depending upon the properties of the donor and the acceptor. Our results
are consistent with models that were developed earlier by Hermansson and
by Qian and Krimm in relation to blue vs red shifting in hydrogen bond
formation. These models invoke the derivatives of the permanent and the
induced dipole moments of the donor molecule.,
DOI = 10.1007/s00894-008-0307-y,
ISSN = 1610-2940,
Unique-ID = ISI:000257330700007,
L. Bendova-Biedermannova, P. Hobza, and J. Vondrasek, "Identifying stabilizing key residues in proteins using interresidue
interaction energy matrix," PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS, vol. 72, iss. 1, pp. 402-413, 2008.
[Bibtex]
@article ISI:000256609800035,
Author = Bendova-Biedermannova, Lada and Hobza, Pavel and Vondrasek, Jiri,
Title = Identifying stabilizing key residues in proteins using interresidue
interaction energy matrix,
Journal = PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS,
Year = 2008,
Volume = 72,
Number = 1,
Pages = 402-413,
Month = JUL,
Abstract = We are proposing an interresidue interaction energy map (IEM) - a new
tool for protein structure analysis and protein bioinformatics. This
approach employs the sum of pair-wise interaction energies of a
particular residue as a measure of its structural importance. We will
show that the IEM can serve as a means for identifying key residues
responsible for the stability of a protein. Our method can be compared
with the interresidue contact map but has the advantage of weighting the
contacts by the stabilization energy content which they bring to the
protein structure. For the theoretical adjustment of the proposed
method, we chose the Trp-cage mini protein as a model system to compare
a spectrum of computational methods ranging from the ab initio MP2 level
through the DFT method to empirical force-field methods. The IEM method
correctly identifies Tryptophane 6 as the key residue in the Trp-cage.
The other residues with the highest stabilizing contributions correspond
to the structurally important positions in the protein. We have further
tested our method on the Trp-Cage miniprotein - a P12W mutant of the
Trp-cage and on two proteins from the rubredoxin family that differ in
their thermostability. Our method correctly identified the
thermodynamically more stable variants in both cases and therefore can
also be used as a tool for the relative measurement of protein
stability. Finally, we will point out the important role played by
dispersion energy, which contributes significantly to the total
stabilization energy and whose role in aromatic pairs is clearly
dominant. Surprisingly, the dispersion energy plays an even more
important role in the interaction of prolines with aromatic systems.,
DOI = 10.1002/prot.21938,
ISSN = 0887-3585,
Unique-ID = ISI:000256609800035,
R. Vacha, L. Cwiklik, J. Rezac, P. Hobza, P. Jungwirth, K. Valsaraj, S. Bahr, and V. Kempter, "Adsorption of aromatic hydrocarbons and ozone at environmental aqueous
surfaces," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 112, iss. 22, pp. 4942-4950, 2008.
[Bibtex]
@article ISI:000256270500012,
Author = Vacha, Robert and Cwiklik, Lukasz and Rezac, Jan and Hobza, Pavel and
Jungwirth, Pavel and Valsaraj, Kalliat and Bahr, Stephan and Kempter,
Volker,
Title = Adsorption of aromatic hydrocarbons and ozone at environmental aqueous
surfaces,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2008,
Volume = 112,
Number = 22,
Pages = 4942-4950,
Month = JUN 5,
Abstract = Adsorption of environmentally important aromatic molecules on a water
surface is studied by means of classical and ab initio molecular
dynamics simulations and by reflection-absorption infrared spectroscopy.
Both techniques show strong activity and orientational preference of
these molecules at the surface. Benzene and naphthalene, which bind
weakly to water surface with a significant contribution of dispersion
interactions, prefer to lie flat on water but retain a large degree of
orientational flexibility. Pyridine is more rigid at the surface. It is
tilted with the nitrogen end having strong hydrogen bonding interactions
with water molecules. The degree of adsorption and orientation of
aromatic molecules on aqueous droplets has atmospheric implications for
heterogeneous ozonolysis, for which the Langmuir-Hinshelwood kinetics
mechanism is discussed. At higher coverages of aromatic molecules the
incoming ozone almost doles not come into contact with the underlying
aqueous phase. This may rationalize the experimental insensitivity of
the ozonolysis on the chemical nature of the substrate on which the
aromatic molecules adsorb.,
DOI = 10.1021/jp711813p,
ISSN = 1089-5639,
Unique-ID = ISI:000256270500012,
W. Wang and P. Hobza, "Theoretical study on the complexes of benzene with isoelectronic
nitrogen-containing heterocycles," CHEMPHYSCHEM, vol. 9, iss. 7, pp. 1003-1009, 2008.
[Bibtex]
@article ISI:000255845500008,
Author = Wang, Weizhou and Hobza, Pavel,
Title = Theoretical study on the complexes of benzene with isoelectronic
nitrogen-containing heterocycles,
Journal = CHEMPHYSCHEM,
Year = 2008,
Volume = 9,
Number = 7,
Pages = 1003-1009,
Month = MAY 2,
Abstract = The pi-pi interactions between benzene and the aromatic nitrogen
heterocycles pyridine, pyrimidine, 1,3,5-triazine, 1,2,3-triazine,
1,2,4,5-tetrazine, and 1,2,3,4,5-pentazine are systematically
investigated. The T-shaped structures of all complexes studied exhibit a
contraction of the C-H bond accompanied by a rather large blue shift
(40-52 cm(-1)) of its stretching frequency, and they ore almost
isoenergetic with the corresponding displaced-parallel structures at
reliable levels of theory. With increasing number of nitrogen atoms in
the heterocycle, the geometries, frequencies, energies, percentage of s
character at C, and the electron density in the C-H sigma antibonding
orbital of the complexes all increase or decrease systematically.
Decomposition analysis of the total binding energy showed that for all
the complexes, the dispersion energy is the dominant attractive
contribution, and a rather compensated by its exchange counterpart.,
DOI = 10.1002/cphc.200700587,
ISSN = 1439-4235,
Unique-ID = ISI:000255845500008,
W. Wang and P. Hobza, "Origin of the X-Hal (Hal = Cl, Br) bond-length change in the
halogen-bonded complexes," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 112, iss. 17, pp. 4114-4119, 2008.
[Bibtex]
@article ISI:000255292200043,
Author = Wang, Weizhou and Hobza, Pavel,
Title = Origin of the X-Hal (Hal = Cl, Br) bond-length change in the
halogen-bonded complexes,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2008,
Volume = 112,
Number = 17,
Pages = 4114-4119,
Month = MAY 1,
Abstract = The origin of the X-Hal bond-length change in the halogen bond of the
X-Hal...Y type has been investigated at the MP2(full)/6-311++G(d,p)
level of theory using a natural bond orbital analysis, atoms in
molecules procedure, and electrostatic potential fitting methods. Our
results have clearly shown that various theories explaining the nature
of the hydrogen bond cannot be applied to explain the origin of the
X-Hal bond-length change in the halogen bond. We provide a new
explanation for this change. The elongation of the X-Hal bond length is
caused by the electron-density transfer to the X-Hal sigma*
antibonding orbital. For the blue-shifting halogen bond, the
electron-density transfer to the X-Hal pi* antibonding orbital is only
of minor importance; it is the electrostatic attractive interaction that
causes the X-Hal bond contraction.,
DOI = 10.1021/jp710992h,
ISSN = 1089-5639,
Unique-ID = ISI:000255292200043,
H. Valdes, V. Klusak, M. Pitonak, O. Exner, I. Stary, P. Hobza, and L. Rulisek, "Evaluation of the intramolecular basis set superposition error in the
calculations of larger molecules: [n]Helicenes and Phe-Gly-Phe
tripeptide," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 29, iss. 6, pp. 861-870, 2008.
[Bibtex]
@article ISI:000254766400002,
Author = Valdes, Haydee and Klusak, Vojtech and Pitonak, Michal and Exner, Otto
and Stary, Ivo and Hobza, Pavel and Rulisek, Lubomir,
Title = Evaluation of the intramolecular basis set superposition error in the
calculations of larger molecules: [n]Helicenes and Phe-Gly-Phe
tripeptide,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 2008,
Volume = 29,
Number = 6,
Pages = 861-870,
Month = APR 30,
Abstract = Correlated ab initio calculations on large systems, such as the popular
MP2 (or RI-MP2) method, suffer from the intramolecular basis set
superposition error (BSSE). This error is typically manifested in
molecules with folded structures, characterized by intramolecular
dispersion interactions. It can dramatically affect the energy
differences between various conformers as well as intramolecular
stabilities, and it can even impair the accuracy of the predictions of
the equilibrium molecular structures. In this study, we will present two
extreme cases of intramolecular BSSE, the internal stability of
[n]helicene molecules and the relative energies of various conformers
of phenylalanyl-glycyl-phenylalanine tripeptide (Phe-Gly-Phe), and
compare the calculated data with benchmark values (experimental or
high-level theoretical data). As a practical and cheap solution to the
accurate treatment of the systems with large anticipated value of
intramolecular BSSE, the recently developed density functional method
augmented with an empirical dispersion term (DFT-D) is proposed and
shown to provide very good results in both of the above described
representative cases. (c) 2007 Wiley Periodicals, Inc.,
DOI = 10.1002/jcc.20841,
ISSN = 0192-8651,
Unique-ID = ISI:000254766400002,
J. Cerny, X. Tong, P. Hobza, and K. Mueller-Dethlefs, "State of the art theoretical study and comparison to experiment for the
phenol center dot center dot center dot argon complex," JOURNAL OF CHEMICAL PHYSICS, vol. 128, iss. 11, 2008.
[Bibtex]
@article ISI:000254292500039,
Author = Cerny, Jiri and Tong, Xin and Hobza, Pavel and Mueller-Dethlefs, Klaus,
Title = State of the art theoretical study and comparison to experiment for the
phenol center dot center dot center dot argon complex,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 2008,
Volume = 128,
Number = 11,
Month = MAR 21,
Abstract = The phenol center dot center dot center dot argon complex was studied by
means of various high level ab initio quantum mechanics methods and high
resolution threshold ionization spectroscopy. The structure and
stabilization energy of different conformers were determined.
Stabilization energy of van der Waals bonded and H-bonded PhOH center
dot center dot center dot Ar complex determined at CCSD(T) complete
basis set (CBS) level for CP-RI-MP2/cc-pVTZ/Ar aug-cc-pVTZ geometries
amount to 434 and 285 cm(-1). The CCSD(T)/CBS were constructed either as
a sum of MP2/CBS interaction energy and CCSD(T) correction term
[difference between CCSD(T) and MP2 correlation energies determined
with medium basis set] or directly from CCSD(T)/aug-cc-pVDZ and
aug-cc-pVTZ energies. Both schemes provide very similar values. Harmonic
vibrational analysis revealed that the H-bonded structure does not
represent energy minimum but first order transition structure. The
respective imaginary vibrational mode (16 cm(-1)) connects two possible
argon locations-above and below the phenol aromatic ring. Including the
Delta ZPVE, we obtained stabilization enthalpy at 0 K of 389 cm(-1).
This value is marginally higher (25-35 cm(-1), 0.07-0.10 kcal/mol) than
the experimental value. The determination of Delta ZPVE constitutes the
most significant error and possible improvements should come from more
accurate evaluation of the (nonharmonic) vibrational frequencies. (c)
2008 American Institute of Physics.,
DOI = 10.1063/1.2838185,
Article-Number = 114319,
ISSN = 0021-9606,
Unique-ID = ISI:000254292500039,
K. E. Riley and P. Hobza, "A DFT-D investigation of the mechanisms for activation of the wild-type
and S810L mutated mineralocorticoid receptor by steroid hormones," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 112, iss. 10, pp. 3157-3163, 2008.
[Bibtex]
@article ISI:000253784700052,
Author = Riley, Kevin E. and Hobza, Pavel,
Title = A DFT-D investigation of the mechanisms for activation of the wild-type
and S810L mutated mineralocorticoid receptor by steroid hormones,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2008,
Volume = 112,
Number = 10,
Pages = 3157-3163,
Month = MAR 13,
Abstract = In this work; we investigate the mode of binding of several steroid
hormones, namely aldosterone, deoxycorticosterone, and progesterone to
the wild-type and S810L mutated mineralocorticoid (MR) receptor using
the newly formulated density functional theory with an empirical
dispersion term (DFT-D) molecular electronic structure method. It is
found that the MR agonists, aldosterone and deoxycorticosterone, form
tight hydrogen bonds with residues Thr945 and Asn770, which leads to the
formation of hydrogen bond networks near the steroid D-ring, allowing
for activation of this transcription factor. Progesterone, an MR
antagonist, fails to form the necessary hydrogen bonds near the steroid
D-ring. Progesterone is known to be an agonist of the mutated S810L MR
receptor. Our studies indicate that this is possible because of a strong
hydrogen bond between progesterone and Thr945 and a relatively strong
hydrophobic interaction between progesterone and Asn770.,
DOI = 10.1021/jp076362b,
ISSN = 1520-6106,
Unique-ID = ISI:000253784700052,
D. Nachtigallova, P. Hobza, and V. Spirko, "Assigning the NH stretches of the Guanine tautomers using adiabatic
separation: CCSD(T) benchmark calculations," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 112, iss. 9, pp. 1854-1856, 2008.
[Bibtex]
@article ISI:000253512600002,
Author = Nachtigallova, Dana and Hobza, Pavel and Spirko, Vladimir,
Title = Assigning the NH stretches of the Guanine tautomers using adiabatic
separation: CCSD(T) benchmark calculations,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2008,
Volume = 112,
Number = 9,
Pages = 1854-1856,
Month = MAR 6,
Abstract = Using an adiabatic separation of the NH stretching vibration from the
remaining vibrational molecular motions, the NH fundamental frequencies
and absolute intensities of several keto/enol and 7/9NH tautomers of
guanine are evaluated ab initio within the framework of a
one-dimensional ``semirigid'' stretching Hamiltonian. The frequencies
(calculated by means of the standard MP2, CCSD(T) and DFT procedures)
are in a close one-to-one harmony with their experimental counterparts,
thus evidencing the adequacy of the used separation for reliable
assigning of the NH stretches in the vibrational spectra of very large
molecular systems.,
DOI = 10.1021/jp711151a,
ISSN = 1089-5639,
Unique-ID = ISI:000253512600002,
K. E. Riley and P. Hobza, "Investigations into the nature of halogen bonding including symmetry
adapted perturbation theory analyses," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 4, iss. 2, pp. 232-242, 2008.
[Bibtex]
@article ISI:000253166000003,
Author = Riley, Kevin E. and Hobza, Pavel,
Title = Investigations into the nature of halogen bonding including symmetry
adapted perturbation theory analyses,
Journal = JOURNAL OF CHEMICAL THEORY AND COMPUTATION,
Year = 2008,
Volume = 4,
Number = 2,
Pages = 232-242,
Month = FEB,
Abstract = In recent years it has been recognized that, because of their unique
properties, halogen bonds have tremendous potential in the development
of new pharmaceutical compounds and materials. In this study we
investigate the phenomenon of halogen bonding by carrying out ab initio
calculations on the halomethane-formaldehyde complexes as well as the
fluorine substituted F(n)H(3-n)CX center dot center dot center dot
OCH(2) dimers, where the halogen bonding. halogens (X) are chlorine,
bromine, and iodine. Coupled cluster (CCSD(T)/aug-cc-pVTZ) calculations
indicate that the binding energies for these type of interactions lie in
the range between - 1.05 kcal/mol (H(3)CCl center dot center dot center
dot OCH(2)) and -3.72 kcal/mol (F(3)Cl center dot center dot center dot
OCH(2)). One of the most important findings in this study is that,
according to symmetry adapted perturbation theory (SAPT) analyses,
halogen bonds are largely dependent on both electrostatic and dispersion
type interactions. As the halogen atom involved in halogen bonding
becomes larger the interaction strength for this type of interaction
also gets larger and, interestingly, more electrostatic (and less
dispersive) in character. Halogen bonding interactions also become
stronger and more electrostatic upon substitution of (the very
electronegative) fluorines onto the halomethane molecule.,
DOI = 10.1021/ct700216w,
ISSN = 1549-9618,
Unique-ID = ISI:000253166000003,
J. Rezac, P. Jurecka, K. E. Riley, J. Cerny, H. Valdes, K. Pluhackova, K. Berka, T. Rezac, M. Pitonak, J. Vondrasek, and P. Hobza, "QUANTUM CHEMICAL BENCHMARK ENERGY AND GEOMETRY DATABASE FOR MOLECULAR
CLUSTERS AND COMPLEX MOLECULAR SYSTEMS (www.begdb.com): A USERS MANUAL
AND EXAMPLES," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 73, iss. 10, pp. 1261-1270, 2008.
[Bibtex]
@article ISI:000263121400003,
Author = Rezac, Jan and Jurecka, Petr and Riley, Kevin E. and Cerny, Jiri and
Valdes, Haydee and Pluhackova, Kristyna and Berka, Karel and Rezac,
Tomas and Pitonak, Michal and Vondrasek, Jiri and Hobza, Pavel,
Title = QUANTUM CHEMICAL BENCHMARK ENERGY AND GEOMETRY DATABASE FOR MOLECULAR
CLUSTERS AND COMPLEX MOLECULAR SYSTEMS (www.begdb.com): A USERS MANUAL
AND EXAMPLES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2008,
Volume = 73,
Number = 10,
Pages = 1261-1270,
Abstract = Our previous benchmark CCSD(T)/ complete basis set limit calculations
were collected into a database named begdb - Benchmark Energy and
Geometry DataBase. Web-based interface to this database was prepared and
is available at www.begdb.com. Users can browse, search and plot the
data online or download structures and energy tables.,
DOI = 10.1135/cccc20081261,
ISSN = 0010-0765,
Unique-ID = ISI:000263121400003,
J. Rezac and P. Hobza, "Correlation between the thermodynamic stability of DNA duplexes and the
interaction and solvation energies of DNA building blocks," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 73, iss. 2, pp. 161-174, 2008.
[Bibtex]
@article ISI:000253884000003,
Author = Rezac, Jan and Hobza, Pavel,
Title = Correlation between the thermodynamic stability of DNA duplexes and the
interaction and solvation energies of DNA building blocks,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2008,
Volume = 73,
Number = 2,
Pages = 161-174,
Abstract = The unwinding Gibbs energy (or duplex dissociation energy) is an
important measure of the thermodynamic stability of DNA oligomers. This
value can be measured experimentally or predicted by empirical models
parametrised on experimental data. Our previously developed model based
on accurate DFT-D calculations of interaction energies between nucleic
acid bases corrected for solvation contribution. This work was
successfully extended to cover variable lengths of oligomers. This model
was further applied to oligomers containing inosine, an unnatural base.
The results, however, are not satisfactory and it is clear that the
model does not take into account all variables contributing to DNA
stability. Inclusion of the backbone deformation energy did not improve
the model. We also compared models based on DFT-D and forcefield
calculations. Forcefield performs well in this application, because the
systematic error in interaction energies is cancelled in the fitting
procedure.,
DOI = 10.1135/cccc20080161,
ISSN = 0010-0765,
Unique-ID = ISI:000253884000003,
W. Wang and P. Hobza, "APPLICATION OF BERLIN'S THEOREM TO BOND-LENGTH CHANGES IN ISOLATED
MOLECULES AND RED- AND BLUE-SHIFTING H-BONDED CLUSTERS," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 73, iss. 6-7, pp. 862-872, 2008.
[Bibtex]
@article ISI:000260536700010,
Author = Wang, Weizhou and Hobza, Pavel,
Title = APPLICATION OF BERLIN'S THEOREM TO BOND-LENGTH CHANGES IN ISOLATED
MOLECULES AND RED- AND BLUE-SHIFTING H-BONDED CLUSTERS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2008,
Volume = 73,
Number = 6-7,
Pages = 862-872,
Abstract = The origin of the bond-length change in molecule or molecular cluster
has been investigated at the MP2/aug-cc-pVDZ level of theory using the
electrostatic potential or the electron density difference analysis
method. Our results have clearly shown that the bond-length change of a
chemical bond is determined mainly by the balance of the electrostatic
forces exerted by electrons on the two nuclei. The factors that affect
the balance of the electrostatic forces include four parts: ( i) The
abstraction of the electron density from Berlin's binding region between
the two nuclei. ( ii) The accumulation of the electron density in
Berlin's antibinding regions. ( iii) The accumulation of the electron
density in Berlin's binding region between the two nuclei. ( iv) The
abstraction of the electron density from Berlin's antibinding regions.
Using the change of the electron density around the two nuclei of a
chemical bond, we have succeeded in explaining two important chemical
phenomena: ( i) breakdown of bond length-bond strength correlation; (
ii) the bond-length change in the hydrogen bond.,
DOI = 10.1135/cccc20080862,
ISSN = 0010-0765,
Unique-ID = ISI:000260536700010,
J. Rezac, K. Berka, D. Horinek, P. Hobza, and J. Vondrasek, "THE STABILIZATION ENERGY OF THE GLU-LYS SALT BRIDGE IN THE PROTEIN/WATER
ENVIRONMENT: CORRELATED QUANTUM CHEMICAL ab initio, DFT AND EMPIRICAL
POTENTIAL STUDIES," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 73, iss. 6-7, pp. 921-936, 2008.
[Bibtex]
@article ISI:000260536700014,
Author = Rezac, Jan and Berka, Karel and Horinek, Dominik and Hobza, Pavel and
Vondrasek, Jiri,
Title = THE STABILIZATION ENERGY OF THE GLU-LYS SALT BRIDGE IN THE PROTEIN/WATER
ENVIRONMENT: CORRELATED QUANTUM CHEMICAL ab initio, DFT AND EMPIRICAL
POTENTIAL STUDIES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2008,
Volume = 73,
Number = 6-7,
Pages = 921-936,
Abstract = The stabilization energies of Glu-Lys salt bridges are calculated at the
CCSD(T) complete basis set limit to provide a reasonable description of
the strength of the ion-pair bond in the gas phase. The effect of the
environment (protein with epsilon = 4 and water with epsilon = 80) on
the stabilization energy was introduced via a modification of the
quantum chemical DFT energy, for which the COSMO methodology was
adopted. The other (standard) approach was based on incorporating a
dielectric constant into the Coulomb electrostatic term of the Amber
empirical potential function and utilizing the generalized Born model
implemented in the Amber program. The environment affects the
stabilization energy of the salt bridge dramatically: The protein
reduces the energy to less than one half of the original value, whereas
water sometimes changes stabilization to destabilization. Both
theoretical procedures, based on completely different theoretical
backgrounds, yield very similar results, which strongly support their
validity. An ion pair is converted to an ion-neutral pair when its pH is
changed. This transformation is connected with a strong reduction of the
stabilization energy regardless of the environment. The substantial
differences in the stabilization energies of ion pairs and ion-neutral
pairs contradict the negligible changes of free energy detected
experimentally. Evidently, the contribution of formation and hydration
entropy is significant and compensates for the large stabilization
energies.,
DOI = 10.1135/cccc20080921,
ISSN = 0010-0765,
Unique-ID = ISI:000260536700014,
H. Valdes, V. Spiwok, J. Rezac, D. Reha, A. G. Abo-Riziq, M. S. de Vries, and P. Hobza, "Potential-energy and free-energy surfaces of glycyl-phenylalanyl-alanine
(GFA) tripeptide: Experiment and theory," CHEMISTRY-A EUROPEAN JOURNAL, vol. 14, iss. 16, pp. 4886-4898, 2008.
[Bibtex]
@article ISI:000256854600015,
Author = Valdes, Haydee and Spiwok, Vojtech and Rezac, Jan and Reha, David and
Abo-Riziq, Ali G. and de Vries, Mattanjah S. and Hobza, Pavel,
Title = Potential-energy and free-energy surfaces of glycyl-phenylalanyl-alanine
(GFA) tripeptide: Experiment and theory,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2008,
Volume = 14,
Number = 16,
Pages = 4886-4898,
Abstract = The free-energy surface (FES) of glycyl-phenylalanyl-alanine (GFA)
tripeptide was explored by molecular dynamics (MD) simulations in
combination with high-level correlated ab initio quantum chemical
calculations and metadynamics. Both the MD and metadynamics employed the
tight-binding DFT-D method instead of the AMBER force field, which
yielded inaccurate results. We classified the minima localised in the
FESs as follows: a) the backbone-conformation at arrangement; and b) the
existence of a CCOH center dot center dot center dot OC intramolecular
H-bond (families CO2Hfree and CO2Hbonded). Comparison with experimental
results showed that the most stable minima in the FES correspond to the
experimentally observed structures. Remarkably, however, we did not
observe experimentally the CO2Hbonded family (also predicted by
metadynamics), although its stability is comparable to that of the
CO2Hfee structures. This fact was explained by the former's short
excitedstate lifetime. We also carried out ab initio calculations using
DFT-D and the M06-2X functional. ne importance of the dispersion energy
in stabilising peptide conformers is well reflected by our pioneer
analysis using the DFT-SAPT method to explore the nature of the
backbone/side-chain interactions.,
DOI = 10.1002/chem.200800085,
ISSN = 0947-6539,
Unique-ID = ISI:000256854600015,
Blue-Shifting Hydrogen Bond and Dihydrogen Bond," CHEMICKE LISTY, vol. 102, iss. 10, pp. 884-888, 2008.
[Bibtex]
@article ISI:000260453700005,
Author = Hobza, Pavel,
Title = Non-Covalent Interactions with Participation of Hydrogen: Hydrogen Bond,
Blue-Shifting Hydrogen Bond and Dihydrogen Bond,
Journal = CHEMICKE LISTY,
Year = 2008,
Volume = 102,
Number = 10,
Pages = 884-888,
Abstract = Non-covalent interactions with participation of hydrogen are the
strongest and most frequent of non-covalent interactions in nature.
Their role in chemistry and especially in biodisciplines is unique.,
ISSN = 0009-2770,
Unique-ID = ISI:000260453700005,
P. Hobza, "Stacking interactions," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 10, iss. 19, pp. 2581-2583, 2008.
[Bibtex]
@article ISI:000255739200001,
Author = Hobza, Pavel,
Title = Stacking interactions,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2008,
Volume = 10,
Number = 19,
Pages = 2581-2583,
DOI = 10.1039/b805489b,
ISSN = 1463-9076,
Unique-ID = ISI:000255739200001,
J. Sponer, K. E. Riley, and P. Hobza, "Nature and magnitude of aromatic stacking of nucleic acid bases," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 10, iss. 19, pp. 2595-2610, 2008.
[Bibtex]
@article ISI:000255739200003,
Author = Sponer, Jiri and Riley, Kevin E. and Hobza, Pavel,
Title = Nature and magnitude of aromatic stacking of nucleic acid bases,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2008,
Volume = 10,
Number = 19,
Pages = 2595-2610,
Abstract = This review summarises recent advances in quantum chemical calculations
of base-stacking forces in nucleic acids. We explain in detail the very
complex relationship between the gas-phase base-stacking energies, as
revealed by quantum chemical (QM) calculations, and the highly variable
roles of these interactions in nucleic acids. This issue is rarely
discussed in quantum chemical and physical chemistry literature. We
further extensively discuss methods that are available for base-stacking
studies, complexity of comparison of stacking calculations with gas
phase experiments, balance of forces in stacked complexes of nucleic
acid bases, and the relation between QM and force field descriptions. We
also review all recent calculations on base- stacking systems, including
details analysis of the B-DNA stacking. Specific attention is paid to
the highest accuracy QM calculations, to the decomposition of the
interactions, and development of dispersion-balanced DFT methods. Future
prospects of computational studies of base stacking are discussed.,
DOI = 10.1039/b719370j,
ISSN = 1463-9076,
Unique-ID = ISI:000255739200003,
H. Valdes, K. Pluhackova, M. Pitonak, J. Rezac, and P. Hobza, "Benchmark database on isolated small peptides containing an aromatic
side chain: comparison between wave function and density functional
theory methods and empirical force field," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 10, iss. 19, pp. 2747-2757, 2008.
[Bibtex]
@article ISI:000255739200018,
Author = Valdes, Haydee and Pluhackova, Kristyna and Pitonak, Michal and Rezac,
Jan and Hobza, Pavel,
Title = Benchmark database on isolated small peptides containing an aromatic
side chain: comparison between wave function and density functional
theory methods and empirical force field,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2008,
Volume = 10,
Number = 19,
Pages = 2747-2757,
Abstract = A detailed quantum chemical study on five peptides (WG, WGG, FGG, GGF
and GFA) containing the residues phenylalanyl (F), glycyl (G),
tryptophyl (W) and alanyl (A) -where F and W are of aromatic character
-is presented. When investigating isolated small peptides, the
dispersion interaction is the dominant attractive force in the peptide
backbone -aromatic side chain intramolecular interaction. Consequently,
an accurate theoretical study of these systems requires the use of a
methodology covering properly the London dispersion forces. For this
reason we have assessed the performance of the MP2, SCS-MP2, MP3,
TPSS-D, PBE-D, M062X, BH\&H, TPSS, B3LYP, tight-binding DFT-D methods
and. 99 empirical force field compared to CCSD(T)/complete basis set
(CBS) limit benchmark data. All the DFT techniques with a `-D' symbol
have been augmented by empirical dispersion energy while the M06-2X
functional was parameterized to cover the London dispersion energy. For
the systems here studied we have concluded that the use of the. 99 force
field is not recommended mainly due to problems concerning the
assignment of reliable atomic charges. Tight-binding DFT-D is efficient
as a screening tool providing reliable geometries. Among the DFT
functionals, the M06-2X and TPSS-D show the best performance what is
explained by the fact that both procedures cover the dispersion energy.
The B3LYP and TPSS functionals -not covering this energy-fail
systematically. Both, electronic energies and geometries obtained by
means of the wave-function theory methods compare satisfactorily with
the CCSD(T)/CBS benchmark data.,
DOI = 10.1039/b719294k,
ISSN = 1463-9076,
Unique-ID = ISI:000255739200018,
J. Cerny, X. Tong, P. Hobza, and K. Mueller-Dethlefs, "Competition between stacking and hydrogen bonding: theoretical study of
the phenol center dot center dot center dot Ar cation and neutral
complex and comparison to experiment," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 10, iss. 19, pp. 2780-2784, 2008.
[Bibtex]
@article ISI:000255739200022,
Author = Cerny, Jiri and Tong, Xin and Hobza, Pavel and Mueller-Dethlefs, Klaus,
Title = Competition between stacking and hydrogen bonding: theoretical study of
the phenol center dot center dot center dot Ar cation and neutral
complex and comparison to experiment,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2008,
Volume = 10,
Number = 19,
Pages = 2780-2784,
Abstract = Experimental results obtained previously for vdW-bonded and H-bonded
phenol center dot center dot center dot argon (PhOH center dot center
dot center dot Ar) complexes in their S(0) and D(0) states are combined
with ab initio quantum-chemical theoretical results. Such a combination
allows us to present a ``complete'' description of the geometry,
relative energies, interaction energies and enthalpies of PhOH center
dot center dot center dot Ar complexes. Based on a minimum-energy-path
study, the transition structures and barrier heights related to
transitions between stable conformers are also presented. For the
presented structures, the agreement between the theoretical interaction
enthalpy at 0 K with experimentally obtained values is very good. On the
other hand, for numerical harmonic-frequency calculations we find a very
poor performance for the neutral PhOH center dot center dot center dot
Ar complex and complete failure for the studied complexes in their
cationic form.,
DOI = 10.1039/b801460b,
ISSN = 1463-9076,
Unique-ID = ISI:000255739200022,
M. P. Callahan, Z. Gengeliczki, N. Svadlenak, H. Valdes, P. Hobza, and M. S. de Vries, "Non-standard base pairing and stacked structures in methyl xanthine
clusters," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 10, iss. 19, pp. 2819-2826, 2008.
[Bibtex]
@article ISI:000255739200028,
Author = Callahan, Michael P. and Gengeliczki, Zsolt and Svadlenak, Nathan and
Valdes, Haydee and Hobza, Pavel and de Vries, Mattanjah S.,
Title = Non-standard base pairing and stacked structures in methyl xanthine
clusters,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2008,
Volume = 10,
Number = 19,
Pages = 2819-2826,
Abstract = We present resonant two-photon ionization and IR-UV double resonance
spectra of methylated xanthine derivatives including 7-methylxanthine
dimer and theobromine dimer seeded in a supersonic jet by laser
desorption. For 7-methylxanthine, theophylline and theobromine monomer
we assign the lowest energy tautomer based on comparison with IR-UV
double resonance spectra and calculated IR frequencies. For the
7-methylxanthine dimer, we observe hydrogen bonding on the N3H position
suggesting 3 possible combinations, one that is reverse Watson-Crick
type and two that are reverse Hoogsteen type. For the theobromine dimer,
we observe a stacked structure. For trimethylxanthine dimers we infer a
stacked structure as well.,
DOI = 10.1039/b719874d,
ISSN = 1463-9076,
Unique-ID = ISI:000255739200028,
D. Nachtigallova, P. Hobza, and H. Ritze, "Electronic splitting in the excited states of DNA base homodimers and
-trimers: an evaluation of short-range and Coulombic interactions," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 10, iss. 37, pp. 5689-5697, 2008.
[Bibtex]
@article ISI:000259381000004,
Author = Nachtigallova, Dana and Hobza, Pavel and Ritze, Hans-Hermann,
Title = Electronic splitting in the excited states of DNA base homodimers and
-trimers: an evaluation of short-range and Coulombic interactions,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2008,
Volume = 10,
Number = 37,
Pages = 5689-5697,
Abstract = The nature of the electronic interactions of the stacked nucleic-acid
bases (adenine, thymine, cytosine, and uracil) in homodimer and -trimer
complexes in their electronically excited states was investigated and
analysed in terms of orbital-overlap and Coulombic interactions. The
mutual orientations of the adjacent bases were selected so as to
correspond to the A-and B-DNA conformations. The extent of the
electronic interaction is larger for the former conformation. It is
shown that the orbital-overlap interactions at the distance of two bases
relevant to the DNA structure do not contribute significantly to the
overall electronic coupling. Only the states which are caused by the (pi
-> pi*) transitions manifest an electronic coupling.,
DOI = 10.1039/b806323k,
ISSN = 1463-9076,
Unique-ID = ISI:000259381000004,
L. Biedermannova, K. E. Riley, K. Berka, P. Hobza, and J. Vondrasek, "Another role of proline: stabilization interactions in proteins and
protein complexes concerning proline and tryptophane," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 10, iss. 42, pp. 6350-6359, 2008.
[Bibtex]
@article ISI:000260485600002,
Author = Biedermannova, Lada and Riley, Kevin E. and Berka, Karel and Hobza,
Pavel and Vondrasek, Jiri,
Title = Another role of proline: stabilization interactions in proteins and
protein complexes concerning proline and tryptophane,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2008,
Volume = 10,
Number = 42,
Pages = 6350-6359,
Abstract = Proline-tryptophan complexes derived from experimental structures are
investigated by quantum chemical procedures known to properly describe
the London dispersion energy. We study two geometrical arrangements: the
`'L-shaped'', stabilized by an H-bond, and the `'stacked-like'', where
the two residues are in parallel orientation without any H-bond.
Interestingly, the interaction energies in both cases are comparable and
very large (similar to 7 kcal mol(-1)). The strength of stabilization in
the stacked arrangement is rather surprising considering the fact that
only one partner has an aromatic character. The interaction energy
decomposition using the SAPT method further demonstrates the very
important role of dispersion energy in such arrangement. To elucidate
the structural features responsible for this unexpectedly large
stabilization we examined the role of the nitrogen heteroatom and the
importance of the cyclicity of the proline residue. We show that the
electrostatic interaction due to the presence of the dipole, caused by
the nitrogen heteroatom, contributes largely to the strength of the
interaction. Nevertheless, the cyclic arrangement of proline, which
allows for the largest amount of dispersive contact with the aromatic
partner, also has a notable-effect. Geometry optimizations carried out
for the `'stacked-like'' complexes show that the arrangements derived
from protein structure are close to their gas phase optimum geometry,
suggesting that the environment has only a minor effect on the geometry
of the interaction. We conclude that the strength of proline
non-covalent interactions, combined with this residue's rigidity, might
be the explanation for its prominent role in protein stabilization and
recognition processes.,
DOI = 10.1039/b805087b,
ISSN = 1463-9076,
Unique-ID = ISI:000260485600002,
[Bibtex]
@article ISI:000256068800004,
Author = Hobza, Jr., Pavel,
Title = The ``Parmenides'' and Plato's theory of ideas,
Journal = FILOSOFICKY CASOPIS,
Year = 2008,
Volume = 56,
Number = 1,
Pages = 45-64,
Abstract = This study investigates Plato's so-called theory of ideas. The starting
point of the investigation is an analysis of the first part of the
Parmenides, where Parmenides presents a broad and thorough criticism of
ideas. This analysis shows, firstly, that the usual rendering of the
Greek terms eidos and idea as Idea (in a metaphysical or Platonic way)
is misleading and that it is more appropriate to render these Greek
terms using the phrases ``characteristic kind'' or ``generic
nature''. In the course of a short excursion into the middle dialogues
it is shown that Plato's ``theory of ideas'' - that is, Socrates'
conception of independent Eide which Parmenides criticises in the
dialogue of the same name - has two sources. (1) In the early dialogues
the terms eidos and idea denoted the characteristic features common to a
group of things - in particular, virtues. (2) In the middle dialogues
``ideas'' were conceived above all as objects of knowledge (cf. the
doctrine of reminiscence), which accounts for the use of
substantialising adjectives and for the qualifier ``in itself'' (cf.
auto to kalon).,
ISSN = 0015-1831,
Unique-ID = ISI:000256068800004,
2007
W. Wang, M. Pitonak, and P. Hobza, "C-H stretching vibrational shift of benzene dimer: Consistency of
experiment and calculation," CHEMPHYSCHEM, vol. 8, iss. 14, pp. 2107-2111, 2007.
[Bibtex]
@article ISI:000250253500012,
Author = Wang, Weizhou and Pitonak, Michal and Hobza, Pavel,
Title = C-H stretching vibrational shift of benzene dimer: Consistency of
experiment and calculation,
Journal = CHEMPHYSCHEM,
Year = 2007,
Volume = 8,
Number = 14,
Pages = 2107-2111,
Month = OCT 8,
Abstract = Three low-energy structures of the benzene dimer are investigated by
several theoretical procedures (RI-MP2, CCSD(T), RI-DFT-D, DFTIBBH\&H)
covering London dispersion energy. The RI-DFT-D and CCSD(T) calculations
are used to verify the DFTIBBH\&H dimer characteristics, as only at this
level can anharmonic calculations be performed. It is ascertained that
the T-shaped (C-2v) structure, in which the C-H stretching frequency of
the proton donor shows a significant blue shift; is not stable at any
level of theory. It is either a transition structure or a minimum which
is easily transformed into a parallel-displaced structure or a T-shaped
(C-s structure, even at low temperature. Consequently, no blue shift can
be detected. On the other hand, the calculated anharmonic IR spectra of
the two most stable structures of benzene dimer, namely, the T-shaped
(C-s) and the parallel-displaced ones, give rise to a small red (and no
blue) shift of the C-H stretching vibration. This finding is fully
consistent with the experimental results.,
DOI = 10.1002/cphc.200700415,
ISSN = 1439-4235,
Unique-ID = ISI:000250253500012,
K. E. Riley and P. Hobza, "Assessment of the MP2 method, along with several basis sets, for the
computation of interaction energies of biologically relevant hydrogen
bonded and dispersion bound complexes," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 111, iss. 33, pp. 8257-8263, 2007.
[Bibtex]
@article ISI:000248758800028,
Author = Riley, Kevin E. and Hobza, Pavel,
Title = Assessment of the MP2 method, along with several basis sets, for the
computation of interaction energies of biologically relevant hydrogen
bonded and dispersion bound complexes,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2007,
Volume = 111,
Number = 33,
Pages = 8257-8263,
Month = AUG 23,
Abstract = In the past several years the MP2 method has been used extensively in
studies of noncovalent interactions within biological systems such as
proteins, DNA/RNA, and protein-ligand complexes. In this work we assess
the performance that can be expected of this method, when paired with
several different medium and extended basis sets, for the accurate
computation of binding energies of hydrogen bonded and dispersion bound
biologically derived complexes. It is found that, overall, the
MP2/cc-pVTZ method produces the best, most well balanced, description of
noncovalent interactions. Another interesting observation made in this
study is that generally the MP2 technique, when paired with any basis
set, does not yield reliable results for cyclic hydrogen bonds such as
those found in nucleic acid base pairs.,
DOI = 10.1021/jp073358r,
ISSN = 1089-5639,
Unique-ID = ISI:000248758800028,
L. Bendova, P. Jurecka, P. Hobza, and J. Vondrasek, "Model of peptide bond-aromatic ring interaction: Correlated ab initio
quantum chemical study," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 111, iss. 33, pp. 9975-9979, 2007.
[Bibtex]
@article ISI:000248759000037,
Author = Bendova, Lada and Jurecka, Petr and Hobza, Pavel and Vondrasek, Jiri,
Title = Model of peptide bond-aromatic ring interaction: Correlated ab initio
quantum chemical study,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2007,
Volume = 111,
Number = 33,
Pages = 9975-9979,
Month = AUG 23,
Abstract = Aromatic ring-peptide bond interactions (modeled as benzene and
formamide, N-methylformamide and N-methylacetamide) are studied by means
of advanced computational chemistry methods: second-order Moller-Plesset
(MP2), coupled-cluster single and double excitation model [CCSD(T)],
and density functional theory with dispersion (DFT-D). The geometrical
preferences of these interactions as well as their interaction energy
content, in both parallel and T-shaped arrangements, are investigated.
The stabilization energy reaches a value of over 5 kcal/mol for the
N-methylformamide-benzene complex at the CCSD(T)/complete basis set
(CBS) level. Decomposition of interaction energy by the
DFT-symmetry-adapted perturbation treatment (SAPT) technique shows that
the parallel and T-shaped arrangements, although similar in their total
interaction energies, differ significantly in the proportion of
electrostatic and dispersion terms.,
DOI = 10.1021/jp072859+,
ISSN = 1520-6106,
Unique-ID = ISI:000248759000037,
R. Sedlak, P. Jurecka, and P. Hobza, "Density functional theory-symmetry adapted perturbation treatment energy
decomposition of nucleic acid base pairs taken from DNA crystal geometry," JOURNAL OF CHEMICAL PHYSICS, vol. 127, iss. 7, 2007.
[Bibtex]
@article ISI:000248905300036,
Author = Sedlak, Robert and Jurecka, Petr and Hobza, Pavel,
Title = Density functional theory-symmetry adapted perturbation treatment energy
decomposition of nucleic acid base pairs taken from DNA crystal geometry,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 2007,
Volume = 127,
Number = 7,
Month = AUG 21,
DOI = 10.1063/1.2759207,
Article-Number = 075104,
ISSN = 0021-9606,
Unique-ID = ISI:000248905300036,
A. Abo-Riziq, B. O. Crews, I. Compagnon, J. Oomens, G. Meijer, G. Von Helden, M. Kabelac, P. Hobza, and M. S. de Vries, "The Mid-IR spectra of 9-ethyl guanine, guanosine, and 2-Deoxyguanosine," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 111, iss. 31, pp. 7529-7536, 2007.
[Bibtex]
@article ISI:000248478700033,
Author = Abo-Riziq, Ali and Crews, Bridgit O. and Compagnon, Isabelle and Oomens,
Jos and Meijer, Gerard and Von Helden, Gert and Kabelac, Martin and
Hobza, Pavel and de Vries, Mattanjah S.,
Title = The Mid-IR spectra of 9-ethyl guanine, guanosine, and 2-Deoxyguanosine,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2007,
Volume = 111,
Number = 31,
Pages = 7529-7536,
Month = AUG 9,
Abstract = We present the mid-IR (400-1800 cm(-1)) spectra of 9-ethyl guanine,
guanosine, and 2-deoxyguanosine measured by IR-UV double-resonance
spectroscopy. We compare the recorded mid-IR spectra with the spectra of
the most stable structures obtained from RI-MP2 and RI-DFT-D
calculations. The results confirm the enol form for all structures and
demonstrate the efficacy of a new approach to DFT calculations that
includes dispersion interactions.,
DOI = 10.1021/jp072183i,
ISSN = 1089-5639,
Unique-ID = ISI:000248478700033,
T. Kubar, P. Jurecka, J. Cerny, J. Rezac, M. Otyepka, H. Valdes, and P. Hobza, "Density-functional, density-functional tight-binding, and wave function
calculations on biomolecular systems," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 111, iss. 26, pp. 5642-5647, 2007.
[Bibtex]
@article ISI:000247573600007,
Author = Kubar, Tomas and Jurecka, Petr and Cerny, Jiri and Rezac, Jan and
Otyepka, Michal and Valdes, Haydee and Hobza, Pavel,
Title = Density-functional, density-functional tight-binding, and wave function
calculations on biomolecular systems,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2007,
Volume = 111,
Number = 26,
Pages = 5642-5647,
Month = JUL 5,
Note = 232nd National Meeting of the American-Chemical-Society, San Francisco,
CA, SEP 10-14, 2006,
Organization = Amer Chem Soc,
Abstract = Recently, two computational approaches that supply a
density-functional-based quantum-chemical method with an empirical term
accounting for London dispersion were introduced and found use in the
studies of biomolecular systems, namely, DFT-D and SCC-DFTB-D. Here, we
examine the performance and usability of these combined techniques for
dealing with several tasks typically occurring in the research of
biomolecules. The interaction energy of small biomolecular complexes
agrees very well with the reference data yielded by correlated ab initio
quantum chemical methods. In real-life studies aimed at interaction
energy, structure, and infrared spectra, the mentioned methods provide
results in good agreement with each other and with experiment (where
available). The very favorable time demands of these approaches are
discussed, and for each of them, a suitable area of use is proposed on
the basis of the results of our analysis.,
DOI = 10.1021/jp068858j,
ISSN = 1089-5639,
Unique-ID = ISI:000247573600007,
M. Kolar and P. Hobza, "Accurate theoretical determination of the structure of aromatic
complexes is complicated: The phenol dimer and Phenol center dot center
dot center dot Methanol cases," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 111, iss. 26, pp. 5851-5854, 2007.
[Bibtex]
@article ISI:000247573600034,
Author = Kolar, Michal and Hobza, Pavel,
Title = Accurate theoretical determination of the structure of aromatic
complexes is complicated: The phenol dimer and Phenol center dot center
dot center dot Methanol cases,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2007,
Volume = 111,
Number = 26,
Pages = 5851-5854,
Month = JUL 5,
Abstract = The structure of the phenol dimer and phenol center dot center dot
center dot methanol complexes was determined by gradient optimization
using the Hartree-Fock (HF), MP2, DFT, and RI-DFT-D methods with various
basis sets. Theoretical rotational constants were compared with
experimental values and the following conclusions were made: (1) HF and
DFT methods fail to predict cluster geometries; (2) MP2 with a medium
basis set yields reliable cluster geometries but only because of a
compensation for errors; (3) when the AO basis set is enlarged, the
geometry becomes incorrect, and the theoretical geometry becomes
reliable only when the higher correlation energy contributions (CCSD(T))
are included; and (4) the RI-DFT-D procedure covering the dispersion
energy provides excellent geometries.,
DOI = 10.1021/jp071486+,
ISSN = 1089-5639,
Unique-ID = ISI:000247573600034,
K. Pluhackova and P. Hobza, "On the nature of the surprisingly small (red) shift in the halothane
...acetone complex," CHEMPHYSCHEM, vol. 8, iss. 9, pp. 1352-1356, 2007.
[Bibtex]
@article ISI:000247811200014,
Author = Pluhackova, Kristyna and Hobza, Pavel,
Title = On the nature of the surprisingly small (red) shift in the halothane
...acetone complex,
Journal = CHEMPHYSCHEM,
Year = 2007,
Volume = 8,
Number = 9,
Pages = 1352-1356,
Month = JUN 25,
Abstract = The halothone center dot center dot center dot acetone and fluoroform
center dot center dot center dot acetone complexes are studied using the
second-order Moller-Plesset (MP2) method with a cc-pVTZ basis set and
the density functional theory (DFT) method with a TZVP basis set.
Whereas halothone exhibits a small red shift upon complexation,
fluoroform shows a pronounced blue shift. To explain this difference in
behavior, we perform symmetry-adopted perturbation theory (SAPT) and
natural bond orbital (NBO) analyses. Although the composition of the
total stabilization energy of each complex is different, that alone does
not provide a satisfactory explanation for the difference in the
spectral shifts. This difference is interpreted as a result of the
interplay of the hyperconjugation and rehybridization mechanisms. The
small and surprising red shift of the C-H stretching frequency of
halothane, which resulted from the complexation of this species with
acetone,is explained by the compensation of the two above-mentioned
mechanisms. On the other hand, the fluoroform center dot center dot
center dot. acetone complex exhibits a blue shift of the C-H stretching
frequency upon complexation, the most likely reason for this shift being
a concerted occurrence of the hyperconjugation and rehybridization
mechanisms. The calculated shift of the C-H stretching vibration
frequencies of halothane (+27cm(-1)) agree with the experimental value
of + 5 cm(-1).,
DOI = 10.1002/cphc.200700153,
ISSN = 1439-4235,
Unique-ID = ISI:000247811200014,
E. Muchova, P. Slavicek, A. L. Sobolewski, and P. Hobza, "Glycine in an electronically excited state: Ab initio electronic
structure and dynamical calculations," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 111, iss. 24, pp. 5259-5269, 2007.
[Bibtex]
@article ISI:000247216600018,
Author = Muchova, Eva and Slavicek, Petr and Sobolewski, Andrzej L. and Hobza,
Pavel,
Title = Glycine in an electronically excited state: Ab initio electronic
structure and dynamical calculations,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2007,
Volume = 111,
Number = 24,
Pages = 5259-5269,
Month = JUN 21,
Abstract = The goal of this study is to explore the photochemical processes
following optical excitation of the glycine molecule into its two
low-lying excited states. We employed electronic structure methods at
various levels to map the PES of the ground state and the two low-lying
excited states of glycine. It follows from our calculations that the
photochemistry of glycine can be regarded as a combination of
photochemical behavior of amines and carboxylic acid. The first channel
(connected to the presence of amino group) results in ultrafast decay,
while the channels characteristic for the carboxylic group occur on a
longer time scale. Dynamical calculations provided the branching ratio
for these channels. We also addressed the question whether
conformationally dependent photochemistry can be observed for glycine.
While electronic structure calculations favor this possibility, the ab
initio multiple spawning (AIMS) calculations showed only minor relevance
of the reaction path resulting in conformationally dependent dynamics.,
DOI = 10.1021/jp071483x,
ISSN = 1089-5639,
Unique-ID = ISI:000247216600018,
E. C. Lee, D. Kim, P. Jurecka, P. Tarakeshwar, P. Hobza, and K. S. Kim, "Understanding of assembly phenomena by aromatic-aromatic interactions:
Benzene dimer and the substituted systems," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 111, iss. 18, pp. 3446-3457, 2007.
[Bibtex]
@article ISI:000246189700003,
Author = Lee, Eun Cheol and Kim, Dongwook and Jurecka, Petr and Tarakeshwar, P.
and Hobza, Pavel and Kim, Kwang S.,
Title = Understanding of assembly phenomena by aromatic-aromatic interactions:
Benzene dimer and the substituted systems,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2007,
Volume = 111,
Number = 18,
Pages = 3446-3457,
Month = MAY 10,
Abstract = Interactions involving aromatic rings are important in
molecular/biomolecular assembly and engineering. As a consequence, there
have been a number of investigations on dimers involving benzene or
other substituted pi systems. In this Feature Article, we examine the
relevance of the magnitudes of their attractive and repulsive
interaction energy components in governing the geometries of several
pi-pi systems. The geometries and the associated binding energies were
evaluated at the complete basis set (CBS) limit of coupled cluster
theory with singles, doubles, and perturbative triples excitations
[CCSD(T)] using a least biased scheme for the given data set. The
results for the benzene dimer indicate that the floppy T-shaped
structure (center-to-center distance: 4.96 angstrom, with an axial
benzene off-centered above the facial benzene) is isoenergetic in
zero-point-energy (ZPE) corrected binding energy (D-0) to the
displaced-stacked structure (vertical interplanar distance: 3.54
angstrom). However, the T-shaped structure is likely to be slightly more
stable (D-0 approximate to 2.4-2.5 kcal/mol) if quadruple excitations
are included in the coupled cluster calculations. The presence of
substituents on the aromatic ring, irrespective of their electron
withdrawing or donating nature, leads to an increase in the binding
energy, and the displaced-stacked conformations are more stabilized than
the T-shaped conformers. This explains the wide prevalence of displaced
stacked structures in organic crystals. Despite that the dispersion
energy is dominating, the substituent as well as the conformational
effects are correlated to the electrostatic interaction. This
electrostatic origin implies that the substituent effect would be
reduced in polar solution, but important in apolar media, in particular,
for assembling processes.,
DOI = 10.1021/jp068635t,
ISSN = 1089-5639,
Unique-ID = ISI:000246189700003,
M. Vrabel, M. Hocek, L. Havran, M. Fojta, I. Votruba, B. Klepetarova, R. Pohl, L. Rulisek, L. Zendlova, P. Hobza, I. Shih, E. Mabery, and R. Mackman, "Purines bearing phenanthroline or bipyridine ligands and their Ru-II
complexes in position 8 as model compounds for electrochemical DNA
labeling - Synthesis, crystal structure, electrochemistry, quantum
chemical calculations, cytostatic and antiviral activity," EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, iss. 12, pp. 1752-1769, 2007.
[Bibtex]
@article ISI:000246404900016,
Author = Vrabel, Milan and Hocek, Michal and Havran, Ludek and Fojta, Miroslav
and Votruba, Ivan and Klepetarova, Blanka and Pohl, Radek and Rulisek,
Lubomir and Zendlova, Lucie and Hobza, Pavel and Shih, I-hung and
Mabery, Eric and Mackman, Richard,
Title = Purines bearing phenanthroline or bipyridine ligands and their Ru-II
complexes in position 8 as model compounds for electrochemical DNA
labeling - Synthesis, crystal structure, electrochemistry, quantum
chemical calculations, cytostatic and antiviral activity,
Journal = EUROPEAN JOURNAL OF INORGANIC CHEMISTRY,
Year = 2007,
Number = 12,
Pages = 1752-1769,
Month = APR,
Abstract = A series of ethynyl- or (4-boronophenyl)bipyridines and -phenanthrolines
were prepared as versatile building blocks for attachment of bidentate
N-ligands to other molecules via cross-coupling reactions. Their
complexation with Ru(bpy)(2)-Cl-2 gave the corresponding Ru-II
complexes. 9-Benzyladenine derivatives bearing the bipyridine or
phenanthroline complexes in position 8, attached via a conjugate
acetylene or phenylene linker were prepared by cross-coupling reactions
of the ethynyl- or 4-boronophenylbipyridines and -phenanthrolines with
9-benzyl-8-bromoadenine. Their complexation with Ru(bpy)(2)Cl-2 afforded
the corresponding Ru complexes as model compounds for electrochemical
DNA labeling. The same compounds were also prepared directly by
cross-coupling of 9-benzyl-8-bromoadenine with Ru complexes of the
alkynes and boronic acids. Both approaches are compared in terms of
potential applications for labeling of nucleic acids. The crystal
structures of two Ru complexes were determined by X-ray diffraction. The
electrochemistry of the model purities bearing the phenanthroline or
bipyridine ligands and the Ru complexes was studied by means of cyclic
or square-wave voltammetry with carbon paste and mercury electrodes. The
experimental redox potentials of the title compounds were compared with
quantum chemical calculations. A very good agreement between experiment
and theory was obtained, with a standard deviation of 0.13 V. It was
shown that theoretical calculations can be of a limited predictive power
for new Run complexes, though it was difficult to reproduce differences
smaller than 0.05 V Several compounds of this series exhibited a
considerable cytostatic effect and activity against the hepatitis C
virus (HCV). (C Wiley-VCH Verlag GmbH \& Co. KGaA, 69451 Weinheim,
Germany, 2007).,
DOI = 10.1002/ejic.200700030,
ISSN = 1434-1948,
Unique-ID = ISI:000246404900016,
L. Zendlova, P. Hobza, and M. Kabelac, "Stability of nucleic acid base pairs in organic solvents: Molecular
dynamics, molecular dynamics/quenching, and correlated ab initio study," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 111, iss. 10, pp. 2591-2609, 2007.
[Bibtex]
@article ISI:000244735300027,
Author = Zendlova, Lucie and Hobza, Pavel and Kabelac, Martin,
Title = Stability of nucleic acid base pairs in organic solvents: Molecular
dynamics, molecular dynamics/quenching, and correlated ab initio study,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2007,
Volume = 111,
Number = 10,
Pages = 2591-2609,
Month = MAR 15,
Abstract = The dynamic structure and potential energy surface of adenine center dot
center dot center dot thymine and guanine center dot center dot center
dot cytosine base pairs and their methylated analogues interacting with
a small number (from 1 to 16 molecules) of organic solvents (methanol,
dimethylsulfoxide, and chloroform) were investigated by various
theoretical approaches starting from simple empirical methods employing
the Cornell et al. force field to highly accurate ab initio quantum
chemical calculations (MP2 and particularly CCSD(T) methods). After the
simple molecular dynamics simulation, the molecular dynamics in
combination with quenching technique was also used. The molecular
dynamics simulations presented here have confirmed previous experimental
and theoretical results from the bulk solvents showing that, whereas in
chloroform the base pairs create hydrogen-bonded structures, in
methanol, stacked structures are preferred. While methanol (like water)
can stabilize the stacked structures of the base pairs by a higher
number of hydrogen bonds than is possible in hydrogen-bonded pairs, the
chloroform molecule lacks such a property, and the hydrogen-bonded
structures are preferred in this solvent. The large volume of the
dimethylsulfoxide molecule is an obstacle for the creation of very
stable hydrogen-bonded and stacked systems, and a preference for
T-shaped structures, especially for complexes of methylated adenine
center dot center dot center dot thymine base pairs, was observed. These
results provide clear evidence that the preference of either the stacked
or the hydrogen-bonded structures of the base pairs in the solvent is
not determined only by bulk properties or the solvent polarity but
rather by specific interactions of the base pair with a small number of
the solvent molecules. These conclusions obtained at the empirical level
were verified also by high-level ab initio correlated calculations.,
DOI = 10.1021/jp065418j,
ISSN = 1520-6106,
Unique-ID = ISI:000244735300027,
J. Cerny, P. Jurecka, P. Hobza, and H. Valdes, "Resolution of identity density functional theory augmented with an
empirical dispersion term (RI-DFT-D): A promising tool for studying
isolated small peptides," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 111, iss. 6, pp. 1146-1154, 2007.
[Bibtex]
@article ISI:000244039600022,
Author = Cerny, Jiri and Jurecka, Petr and Hobza, Pavel and Valdes, Haydee,
Title = Resolution of identity density functional theory augmented with an
empirical dispersion term (RI-DFT-D): A promising tool for studying
isolated small peptides,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2007,
Volume = 111,
Number = 6,
Pages = 1146-1154,
Month = FEB 15,
Abstract = Resolution of identity standard density functional theory augmented with
a damped empirical dispersion term (RI-DFT-D) calculations have been
carried out on a set of lowest energy minima of tryptophyl-glycine
(Trp-Gly) and tryptophyl-glycyl-glycine (Trp-Gly-Gly) peptides. RI-DFT-D
(TPSS/TZVP) results are in excellent agreement with benchmark data based
on the CCSD(T) method. Experimental spectra could be assigned according
to the calculated IR frequencies. Central processing unit (CPU) time
requirements are only slightly higher than those needed for the DFT
calculations. Consequently, RI-DFT-D theory seems to be a promising
methodology for studying oligopeptides with accuracy comparable to ab
initio quantum chemical calculations.,
DOI = 10.1021/jp066504m,
ISSN = 1089-5639,
Unique-ID = ISI:000244039600022,
P. Jurecka, J. Cerny, P. Hobza, and D. R. Salahub, "Density functional theory augmented with an empirical dispersion term.
Interaction energies and geometries of 80 noncovalent complexes compared
with ab initio quantum mechanics calculations," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 28, iss. 2, pp. 555-569, 2007.
[Bibtex]
@article ISI:000243238700011,
Author = Jurecka, Petr and Cerny, Jiri and Hobza, Pavel and Salahub, Dennis R.,
Title = Density functional theory augmented with an empirical dispersion term.
Interaction energies and geometries of 80 noncovalent complexes compared
with ab initio quantum mechanics calculations,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 2007,
Volume = 28,
Number = 2,
Pages = 555-569,
Month = JAN 30,
Abstract = Standard density functional theory (DFT) is augmented with a damped
empirical dispersion term. The damping function is optimized on a small,
well balanced set of 22 van der Waals (vdW) complexes and verified on a
validation set of 58 vdW complexes. Both sets contain biologically
relevant molecules such as nucleic acid bases. Results are in remarkable
agreement with reference high-level wave function data based on the
CCSD(T) method. The geometries obtained by full gradient optimization
are in very good agreement with the best available theoretical
reference. In terms of the standard deviation and average errors,
results including the empirical dispersion term are clearly superior to
all pure density functionals investigated-B-LYP, B3-LYP, PBE, TPSS,
TPSSh, and BH-LYP- and even surpass the MP2/cc-pVTZ method. The
combination of empirical dispersion with the TPSS functional performs
remarkably well. The most critical part of the empirical dispersion
approach is the damping function. The damping parameters should be
optimized for each density functional/basis set combination separately.
To keep the method simple, we optimized mainly a single factor, s(R),
scaling globally the vdW radii. For good results, a basis set of at
least triple-zeta quality is required and diffuse functions are
recommended, since the basis set superposition error seriously
deteriorates the results. On average, the dispersion contribution to the
interaction energy missing in the DFT functionals examined here is about
15 and 100\% for the hydrogen-bonded and stacked complexes considered,
respectively. (C) 2006 Wiley Periodicals. Inc.,
DOI = 10.1002/jcc.20570,
ISSN = 0192-8651,
Unique-ID = ISI:000243238700011,
J. Rejnek and P. Hobza, "Hydrogen-bonded nucleic acid base pairs containing unusual base
tautomers: Complete basis set calculations at the MP2 and CCSD(T) levels," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 111, iss. 3, pp. 641-645, 2007.
[Bibtex]
@article ISI:000243535900020,
Author = Rejnek, Jaroslav and Hobza, Pavel,
Title = Hydrogen-bonded nucleic acid base pairs containing unusual base
tautomers: Complete basis set calculations at the MP2 and CCSD(T) levels,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2007,
Volume = 111,
Number = 3,
Pages = 641-645,
Month = JAN 25,
Abstract = The total interaction energies of altogether 15 hydrogen-bonded nucleic
acid base pairs containing unusual base tautomers were calculated. The
geometry properties of all selected adenine-thymine and guanine-cytosine
hydrogen-bonded base pairs enable their incorporation into DNA. Unusual
base pairing patterns were compared with Watson-Crick H-bonded
structures of the adenine-thymine and guanine-cytosine pairs. The
complete basis set (CBS) limit of the MP2 interaction energy and the
CCSD(T) correction term, determined as the difference between the
CCSD(T) and MP2 interaction energies, was evaluated. Extrapolation to
the MP2 CBS limit was done using the aug-cc-pVDZ and aug-cc-pVTZ
results, and the CCSD(T) correction term was determined with the
6-31G*(0.25) basis set. Final interaction energies were corrected
while taking into account both tautomeric penalization determined at the
CBS level and solvation/desolvation free energies. The situation for the
adenine-thymine pairs is straightforward, and tautomeric pairs are
significantly less stable than the Watson-Crick pair consisting of the
canonical forms. In the case of the guanine-cytosine pair, the
Watson-Crick structure made by canonical forms is again the most stable.
The other two structures are, however, energetically rather similar (by
5 and 6 kcal/mol), which provides a very small but non-negligible chance
of detecting these structures in the DNA double helix (1:5000). Due to
the fact that DNA bases and base pairs incorporated into DNA are
solvated less favorably than in isolated systems, this probability
represents the very upper limit. The results clearly show how precisely
the canonical building blocks of DNA molecules were chosen and how well
their stability is maintained.,
DOI = 10.1021/jp0661692,
ISSN = 1520-6106,
Unique-ID = ISI:000243535900020,
H. Szatylowicz, T. M. Krygowski, and P. Hobza, "How the shape of the NH2 group depends on the substituent effect and
H-bond formation in derivatives of aniline," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 111, iss. 1, pp. 170-175, 2007.
[Bibtex]
@article ISI:000243229000022,
Author = Szatylowicz, Halina and Krygowski, Tadeusz M. and Hobza, Pavel,
Title = How the shape of the NH2 group depends on the substituent effect and
H-bond formation in derivatives of aniline,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2007,
Volume = 111,
Number = 1,
Pages = 170-175,
Month = JAN 11,
Abstract = The geometry and electronic structure of the amino group in aniline and
its derivatives are very sensitive to both intramolecular interactions
such as substituent effects and intermolecular ones such as H-bonding.
An analysis of experimental geometries retrieved from the CSD base and
computational modeling of aniline and its derivatives and their H-bonded
complexes by use of B3LYP/6-311+G** and MP2/aug-cc-pVDZ showed that
the degree of pyramidalization of the amino group depends on H-bonding,
which exists in two forms, (i) NH center dot center dot center dot B
(base) and (ii) N center dot center dot center dot HB (Bronsted acid),
both of which affect the shape of the NH2 group. The effect may be
significantly enhanced by a substituent through resonance interaction
from electron-attracting substituents. The NH center dot center dot
center dot B interactions lead to a substantial planarization of the
group, whereas N center dot center dot center dot HB interactions do
not. The natural bond orbital analysis allowed the authors to show that
the changes in occupancy of the ``lone pair'' orbital and in geometry
parameters describing pyramidalization of the group depend on the
substituent constants.,
DOI = 10.1021/jp065336v,
ISSN = 1089-5639,
Unique-ID = ISI:000243229000022,
R. L. T. Parreira, S. E. Galembeck, and P. Hobza, "On the origin of red and blue shifts of X-H and C-H stretching
vibrations in formic acid (formate ion) and proton donor complexes," CHEMPHYSCHEM, vol. 8, iss. 1, pp. 87-92, 2007.
[Bibtex]
@article ISI:000243502800014,
Author = Parreira, Renato Luis Tame and Galembeck, Sergio Emanuel and Hobza,
Paevel,
Title = On the origin of red and blue shifts of X-H and C-H stretching
vibrations in formic acid (formate ion) and proton donor complexes,
Journal = CHEMPHYSCHEM,
Year = 2007,
Volume = 8,
Number = 1,
Pages = 87-92,
Month = JAN 8,
Abstract = Complexes between formic acid formate anion and various proton donors
(HF, H2O, NH3, and CH4) are studied by the MP2 and B3LYP methods with
the 6-311 + + G(3df,3pd) basis set. Formation of a complex is
characterized by electron-density transfer from electron donor to
ligands. This transfer is much larger with the formate anion, for which
it exceeds 0.1e. Electron-density transfer from electron lone pairs of
the electron donor is directed into sigma* antibonding orbitals of X-H
bonds of the electron acceptor and leads to elongation of the bond and a
red shift of the X-H stretching frequency (standard H-bonding). However,
pronounced electron-density transfer from electron lone pairs of the
electron donor also leads to reorganization of the electron density in
the electron donor, which results in changes in geometry and vibrational
frequency. These changes are largest for the C-H bonds of formic acid
and formate anion, which do not participate in H-bonding. The resulting
blue shift of this stretching frequency is substantial and amounts to
almost 35 and 170 cm(-1), respectively.,
DOI = 10.1002/cphc.200600435,
ISSN = 1439-4235,
Unique-ID = ISI:000243502800014,
biomacromolecules," in COMPUTATIONAL METHODS IN SCIENCE AND ENGINEERING VOL 1: THEORY AND
COMPUTATION: OLD PROBLEMS AND NEW CHALLENGES, 2007, pp. 416-424.
[Bibtex]
@inproceedings ISI:000252146200033,
Author = Hobza, Pavel,
Editor = Maroulis, G and Simos, TE,
Title = Calculations of the stabilization energies of the building blocks of
biomacromolecules,
Booktitle = COMPUTATIONAL METHODS IN SCIENCE AND ENGINEERING VOL 1: THEORY AND
COMPUTATION: OLD PROBLEMS AND NEW CHALLENGES,
Series = AIP CONFERENCE PROCEEDINGS,
Year = 2007,
Volume = 963,
Pages = 416-424,
Note = International Conference on Computational Methods in Science and
Engineering, Corfu, GREECE, SEP 25-30, 2007,
Organization = European Soc Computat Methods Sci \& Engn; Minist Natl Educ \& Religious
Affairs; E4 Comp Engn,
Abstract = Non-covalent interactions play an important role in chemistry, physics
and especially in biodisciplines. They determine structure of
biomacromolecules like DNA and proteins and are responsible for
molecular recognition process. Theoretical evaluation of interaction
energies is difficult and perturbation as well as variation
(supermolecular) methods are briefly described. Accurate interaction
energies are obtained by complete basis set limit calculations providing
large portion of correlation energy is covered (e.g. by performing the
CCSD(T) calculations). A role of H-bonding and stacking interactions in
stabilization of DNA and proteins is described and an importance of
London dispersion energy is pointed out.,
ISSN = 0094-243X,
ISBN = 978-0-7354-0477-9,
Unique-ID = ISI:000252146200033,
H. Ritze, P. Hobza, and D. Nachtigallova, "Electronic coupling in the excited electronic state of stacked DNA base
homodimers," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 9, iss. 14, pp. 1672-1675, 2007.
[Bibtex]
@article ISI:000245304500003,
Author = Ritze, Hans-Hermann and Hobza, Pavel and Nachtigallova, Dana,
Title = Electronic coupling in the excited electronic state of stacked DNA base
homodimers,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2007,
Volume = 9,
Number = 14,
Pages = 1672-1675,
Abstract = The nature of the electronic coupling of stacked nucleic acid bases
adenine (A), thymine (T), and cytosine (C), in A - A, T - T, and C - C
complexes in their excited states was investigated; a different
character of the electronic coupling for the T - T complex was shown.,
DOI = 10.1039/b618382d,
ISSN = 1463-9076,
Unique-ID = ISI:000245304500003,
J. Fanfrlik, D. Hnyk, M. Lepsik, and P. Hobza, "Interaction of heteroboranes with biomolecules - Part 2. The effect of
various metal vertices and exo-substitutions," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 9, iss. 17, pp. 2085-2093, 2007.
[Bibtex]
@article ISI:000246027500006,
Author = Fanfrlik, Jindrich and Hnyk, Drahomir and Lepsik, Martin and Hobza,
Pavel,
Title = Interaction of heteroboranes with biomolecules - Part 2. The effect of
various metal vertices and exo-substitutions,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2007,
Volume = 9,
Number = 17,
Pages = 2085-2093,
Abstract = Icosahedral heteroboranes and especially metallacarboranes, which have
recently been shown to act as potent HIV-1 protease inhibitors, are a
unique class of chemical compounds with unusual properties, one of which
is the formation of dihydrogen bonds with biomolecules. In this study,
we investigate the effect of various metal vertices and
exo-substitutions on several series of heteroboranes, including
11-vertex carborane cages [nido-7,8-C2B9Hn](n-13) (n = 11,12,13),
closo-1-SB11H11, closo-1-NB11H12, metal bis(dicarbollides) [3,3'-M
(1,2-C2B9H11)(2)](n) (M/n = Fe/2-, Co/1-, Ni/0) and fluoro (F), amino
(NH2) and hydroxo (OH) derivatives of the metal bis( dicarbollides).
Besides the properties of isolated systems (geometries, electronic
properties and hydration), we study their interactions with a
tetrapeptide, which models their biomolecular partner. Calculations have
confirmed that the extra hydrogen in [nido-7,8-C2B9H12](-) forms a
bridge, which fluctuates between two stationary states. Using
RESP-derived charges, it was ascertained that the negative charge of
heteroboranes is located mainly on boron-bound hydrogens. An increase of
the negative total charge ( from 0 to - 1 or - 2) of heteroboranes
yields an increase in the stabilisation energies of heteroborane center
dot center dot center dot peptide complexes and also a substantial
increase in the hydration free energies of heteroboranes. Compared to
the substitutions of metal vertices, the exo-substitutions of
metallacarboranes cause a larger increase in stabilisation energies and
a smaller increase in desolvation penalties. These two terms,
stabilisation energies and desolvation penalties, contribute in opposite
directions to the total heteroborane - biomolecule binding energy and
must both be taken into account when designing new HIV-1 protease
inhibitors.,
DOI = 10.1039/b617776j,
ISSN = 1463-9076,
Unique-ID = ISI:000246027500006,
M. Kabelac, H. Valdes, E. C. Sherer, C. J. Cramer, and P. Hobza, "Benchmark RI-MP2 database of nucleic acid base trimers: performance of
different density functional models for prediction of structures and
binding energies," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 9, iss. 36, pp. 5000-5008, 2007.
[Bibtex]
@article ISI:000249432000006,
Author = Kabelac, Martin and Valdes, Haydee and Sherer, Edward C. and Cramer,
Christopher J. and Hobza, Pavel,
Title = Benchmark RI-MP2 database of nucleic acid base trimers: performance of
different density functional models for prediction of structures and
binding energies,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2007,
Volume = 9,
Number = 36,
Pages = 5000-5008,
Abstract = A new database of nucleic acid base trimers has been developed that
includes 141 geometries and stabilization energies obtained at the
RI-MP2 level of theory with the TZVPP basis set. Compared to previously
compiled biologically oriented databases, this new construct includes
considerably more complicated structures; the various intermolecular
interactions in the trimers are quite heterogeneous and in particular
include simultaneous hydrogen bonding and stacking interactions, which
is similar to the situation in actual biopolymers. Validation against
these benchmark data is therefore a more demanding task for approximate
models, since correct descriptions of all energy terms are unlikely to
be accomplished by fortuitous cancellations of systematic errors. The
density functionals TPSS ( both with and without an empirical dispersion
term), PWB6K, M05-2X, and BH\&H, and the self-consistent charge density
functional tight binding method augmented with an empirical dispersion
term (SCC-DFTB-D) were assessed for their abilities accurately to
compute structures and energies. The best reproduction of the BSSE
corrected RI-MP2 stabilization energies was achieved by the TPSS
functional ( TZVPP basis set) combined with empirical dispersion;
removal of the dispersion correction leads to significantly degraded
performance. The M05-2X and PWB6K functionals performed very well in
reproducing the RI-MP2 geometries, but showed a systematic moderate
underestimation of the magnitude of base stacking interactions. The
SCC-DFTB-D method predicts geometries in fair agreement with RI-MP2;
given its computational efficiency it represents a good option for
initial scanning of analogous biopolymeric potential energy surfaces.
BH\&H gives geometries of comparable quality to the other functionals
but significantly overestimates interaction energies other than
stacking.,
DOI = 10.1039/b707182e,
ISSN = 1463-9076,
Unique-ID = ISI:000249432000006,
J. Cerny and P. Hobza, "Non-covalent interactions in biomacromolecules," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 9, iss. 39, pp. 5291-5303, 2007.
[Bibtex]
@article ISI:000249925500010,
Author = Cerny, Jiri and Hobza, Pavel,
Title = Non-covalent interactions in biomacromolecules,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2007,
Volume = 9,
Number = 39,
Pages = 5291-5303,
Abstract = Non-covalent interactions play an important role in chemistry, physics
and especially in biodisciplines. They determine the structure of
biomacromolecules such as DNA and proteins and are responsible for the
molecular recognition process. Theoretical evaluation of interaction
energies is difficult; however, perturbation as well as variation
(supermolecular) methods are briefly described. Accurate interaction
energies can be obtained by complete basis set limit calculations
providing a large portion of correlation energy is covered (e.g. by
performing CCSD(T) calculations). The role of H-bonding and stacking
interactions in the stabilisation of DNA, oligopeptides and proteins is
described, and the importance of London dispersion energy is shown.,
DOI = 10.1039/b704781a,
ISSN = 1463-9076,
Unique-ID = ISI:000249925500010,
K. E. Riley, J. Vondrasek, and P. Hobza, "Performance of the DFT-D method, paired with the PCM implicit solvation
model, for the computation of interaction energies of solvated complexes
of biological interest," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 9, iss. 41, pp. 5555-5560, 2007.
[Bibtex]
@article ISI:000250366900005,
Author = Riley, Kevin E. and Vondrasek, Jiri and Hobza, Pavel,
Title = Performance of the DFT-D method, paired with the PCM implicit solvation
model, for the computation of interaction energies of solvated complexes
of biological interest,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2007,
Volume = 9,
Number = 41,
Pages = 5555-5560,
Abstract = In this work we investigate the performance of the DFT method, augmented
with an empirical dispersion function (DFT-D), paired with the PCM
implicit solvation model, for the computation of noncovalent interaction
energies of biologically-relevant, solvated model complexes. It is found
that this method describes intermolecular interactions within water and
ether ( protein-like) environments with roughly the same accuracy as in
the gas phase. Another important finding is that, when environmental
effects are taken into account, the empirical dispersion term associated
with the DFT-D method need be modified very little ( or not at all), in
order to obtain the optimum, most well balanced, performance.,
DOI = 10.1039/b708089a,
ISSN = 1463-9076,
Unique-ID = ISI:000250366900005,
K. Pluhackova, P. Jurecka, and P. Hobza, "Stabilisation energy of C6H6 center dot center dot center dot C6X6 (X =
F, Cl, Br, I, CN) complexes: complete basis set limit calculations at
MP2 and CCSD(T) levels," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 9, iss. 6, pp. 755-760, 2007.
[Bibtex]
@article ISI:000243928300011,
Author = Pluhackova, Kristyna and Jurecka, Petr and Hobza, Pavel,
Title = Stabilisation energy of C6H6 center dot center dot center dot C6X6 (X =
F, Cl, Br, I, CN) complexes: complete basis set limit calculations at
MP2 and CCSD(T) levels,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2007,
Volume = 9,
Number = 6,
Pages = 755-760,
Abstract = Stabilisation energies of stacked structures of (C6H6C6X6)-C-... (X = F,
Cl, Br, CN) complexes were determined at the CCSD(T) complete basis set
(CBS) limit level. These energies were constructed from MP2/CBS
stabilisation energies and a CCSD(T) correction term determined with a
medium basis set (6-31G**). The former energies were extrapolated
using the two-point formula of Helgaker et al. from aug-cc-pVDZ and
aug-cc-pVTZ Hartree-Fock energies and MP2 correlation energies. The
CCSD(T) correction term is systematically repulsive. The final
CCSD(T)/CBS stabilisation energies are large, considerably larger than
previously calculated and increase in the series as follows:
hexafluorobenzene (6.3 kcal mol(-1)), hexachlorobenzene (8.8 kcal
mol(-1)), hexabromobenzene (8.1 kcal mol(-1)) and hexacyanobenzene (11.0
kcal mol(-1)). MP2/SDD** relativistic calculations performed for all
complexes mentioned and also for benzene(...)hexaiodobenzene have
clearly shown that due to relativistic effects the stabilisation energy
of the hexaiodobenzene complex is lower than that of hexabromobenzene
complex. The decomposition of the total interaction energy to physically
defined energy components was made by using the symmetry adapted
perturbation treatment (SAPT). The main stabilisation contribution for
all complexes investigated is due to London dispersion energy, with the
induction term being smaller. Electrostatic and induction terms which
are attractive are compensated by their exchange counterparts. The
stacked motif in the complexes studied is very stable and might thus be
valuable as a supramolecular synthon.,
DOI = 10.1039/b615318f,
ISSN = 1463-9076,
Unique-ID = ISI:000243928300011,
M. Kabelac and P. Hobza, "Hydration and stability of nucleic acid bases and base pairs," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 9, iss. 8, pp. 903-917, 2007.
[Bibtex]
@article ISI:000244253000001,
Author = Kabelac, Martin and Hobza, Pavel,
Title = Hydration and stability of nucleic acid bases and base pairs,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2007,
Volume = 9,
Number = 8,
Pages = 903-917,
Abstract = Empirical, quantum chemical calculations and molecular dynamics
simulations of the role of a solvent on tautomerism of nucleic acid
bases and structure and properties of nucleic acid base pairs are
summarized. Attention was paid to microhydrated (by one and two water
molecules) complexes, for which structures found by scanning of
empirical potential surfaces were recalculated at a correlated ab initio
level. Additionally, isolated as well as mono-and dihydrated H-bonded,
T-shaped and stacked structures of all possible nucleic acid base pairs
were studied at the same theoretical levels. We demonstrate the strong
influence of a solvent on the tautomeric equilibrium between the
tautomers of bases and on the spatial arrangement of the bases in a base
pair. The results provide clear evidence that the prevalence of either
the stacked or hydrogen-bonded structures of the base pairs in the
solvent is not determined only by its bulk properties, but rather by
specific hydrophilic interactions of the base pair with a small number
of solvent molecules.,
DOI = 10.1039/b614420a,
ISSN = 1463-9076,
Unique-ID = ISI:000244253000001,
M. S. de Vries and P. Hobza, "Gas-phase spectroscopy of biomolecular building blocks," ANNUAL REVIEW OF PHYSICAL CHEMISTRY, vol. 58, pp. 585-612, 2007.
[Bibtex]
@article ISI:000246652300023,
Author = de Vries, Mattanjah S. and Hobza, Pavel,
Title = Gas-phase spectroscopy of biomolecular building blocks,
Journal = ANNUAL REVIEW OF PHYSICAL CHEMISTRY,
Series = Annual Review of Physical Chemistry,
Year = 2007,
Volume = 58,
Pages = 585-612,
Abstract = Gas-phase spectroscopy lends itself ideally to the study of isolated
molecules and provides important data for comparison with theory. In
recent years, we have seen enormous progress in the study of
biomolecular building blocks in the gas phase. The motivation for such
work is threefold: (a) It is important to distinguish between intrinsic
molecular properties and properties that result from the biological
environment. (b) Gas-phase spectroscopy of clusters provides insights
into fundamental interactions and into microsolvation. (c) Gas-phase
data support quantum-chemical calculations. This review focuses on the
current status of (poly)amino acids and DTNA bases. Recent results help
elucidate structure and hydrogen-bonded interactions, as well as
showcase a successful interplay between theory and experiment.,
DOI = 10.1146/annurev.physchem.57.032905.104722,
ISSN = 0066-426X,
ISBN = 978-0-8243-1058-5,
Unique-ID = ISI:000246652300023,
M. Kabelac, E. C. Sherer, C. J. Cramer, and P. Hobza, "DNA base trimers: Empirical and quantum chemical ab initio calculations
versus experiment in vacuo," CHEMISTRY-A EUROPEAN JOURNAL, vol. 13, iss. 7, pp. 2067-2077, 2007.
[Bibtex]
@article ISI:000244914700017,
Author = Kabelac, Martin and Sherer, Edward C. and Cramer, Christopher J. and
Hobza, Pavel,
Title = DNA base trimers: Empirical and quantum chemical ab initio calculations
versus experiment in vacuo,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2007,
Volume = 13,
Number = 7,
Pages = 2067-2077,
Abstract = A complete scan of the potential-energy surfaces for selected DNA base
trimers has been performed by a molecular dynamics/quenching technique
using the force field of Cornell et al. implemented in the AMBER7
program. The resulting most stable/populated structures were then
reoptimized at a correlated ab initio level by employing resolution of
the identity, Moller-Plesset second-order perturbation theory (RI-MP2).
A systematic study of these trimers at such a complete level of
electronic structure theory is presented for the first time. We show
that prior experimental and theoretical interpretations were incorrect
in assuming that the most stable structures of the methylated trimers
corresponded to planar systems characterized by cyclic intermolecular
hydrogen bonding. We found that stacked structures of two bases with the
third base in a T-shape arrangement are the global minima in all of the
methylated systems: they are more stable than the cyclic planar
structures by about 10 kcal mol(-1). The different behaviors of
nonmethylated and methylated trimers is also discussed. ne high-level
geometries and interaction energies computed for the trimers serve also
as a reference for the testing of recently developed density functional
theory (DFT) functionals with respect to their ability to correctly
describe the balance between the electrostatic and dispersion
contributions that bind these trimers together. The recently reported
M052X functional with a polarized triple-zeta basis set predicts 11
uracil trimer interaction energies with a root-mean-square error of 2.3
kcal mol(-1) relative to highly correlated ab initio theoretical
calculations.,
DOI = 10.1002/chem.200601007,
ISSN = 0947-6539,
Unique-ID = ISI:000244914700017,
J. Rezac and P. Hobza, "On the nature of DNA-duplex stability," CHEMISTRY-A EUROPEAN JOURNAL, vol. 13, iss. 10, pp. 2983-2989, 2007.
[Bibtex]
@article ISI:000245389700024,
Author = Rezac, Jan and Hobza, Pavel,
Title = On the nature of DNA-duplex stability,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2007,
Volume = 13,
Number = 10,
Pages = 2983-2989,
Abstract = The unwinding free energy of 128 DNA octamers was correlated with the
sum of interaction energies among DNA bases and their solvation
energies. ne former energies were determined by using the recently
developed density functional theory procedure augmented by London
dispersion energy (RI-DFT-D) that provides accurate hydrogen-bonding and
stacking energies highly comparable with CCSD(T)/complete basis set
limit benchmark data. Efficient tight-binding DFT covering dispersion
energy was also used and yielded satisfactory results. The latter method
can be used for extended systems. The solvation energy was determined by
using a CPCM continuum solvent at HF level calculations. Various models
were adopted to correlate theoretical energies with experimental
unwinding free energies. Unless all energy components (hydrogen-bonding,
intra- and interstrand-stacking, and solvation energies) were included
and weighted individually, no satisfactory correlation resulted. The
most advanced model yielded very close correlation (RMSE=0.32 kcal
mol(-1)) fully comparable with the entirely empirical correlation
introduced in the original paper. 131 Analysis of the theoretical
results shows the importance of inter- and intramolecular stacking
energies, and especially the latter term plays a key role in determining
DNA-duplex stabilization.,
DOI = 10.1002/chem.200601120,
ISSN = 0947-6539,
Unique-ID = ISI:000245389700024,
J. Vondrasek, T. Kubar, F. E. Jenney Jr., M. W. W. Adams, M. Kozisek, J. Cerny, V. Sklenar, and P. Hobza, "Dispersion interactions govern the strong thermal stability of a protein," CHEMISTRY-A EUROPEAN JOURNAL, vol. 13, iss. 32, pp. 9022-9027, 2007.
[Bibtex]
@article ISI:000250913900012,
Author = Vondrasek, Jiri and Kubar, Tomas and Jenney, Jr., Francis E. and Adams,
Michael W. W. and Kozisek, Milan and Cerny, Jiri and Sklenar, Vladimir
and Hobza, Pavel,
Title = Dispersion interactions govern the strong thermal stability of a protein,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2007,
Volume = 13,
Number = 32,
Pages = 9022-9027,
Abstract = Rubredoxin from the hyperthermophile Pyrococcus furiosus (Pf Rd) is an
extremely thermostable protein, which makes it an attractive subject of
protein folding and stability studies. A fundamental question arises as
to what the reason for such extreme stability is and how it can be
elucidated from a complex set of interatomic interactions. We addressed
this issue first theoretically through a computational analysis of the
hydrophobic core of the protein and its mutants, including the
interactions taking place inside the core. Here we show that a single
mutation of one of phenylalanine's residues inside the protein's
hydrophobic core results in a dramatic decrease in its thermal
stability. The calculated unfolding Gibbs energy as well as the
stabilization energy differences between a few core residues follows the
same trend as the melting temperature of protein variants determined
experimentally by microcalorimetry measurements. NMR spectroscopy
experiments have shown that the only part of the protein affected by
mutation is the reasonably rearranged hydrophobic core. It is hence
concluded that stabilization energies, which are dominated by London
dispersion, represent the main source of stability of this protein.,
DOI = 10.1002/chem.200700428,
ISSN = 0947-6539,
Unique-ID = ISI:000250913900012,
[Bibtex]
@article ISI:000248986000008,
Author = Cerny, Jiri and Hobza, Pavel,
Title = Forces of attraction,
Journal = PHOTOCHEMICAL \& PHOTOBIOLOGICAL SCIENCES,
Year = 2007,
Volume = 6,
Number = 9,
Pages = B71,
ISSN = 1474-905X,
Unique-ID = ISI:000248986000008,
[Bibtex]
@article ISI:000248731600008,
Author = Cerny, Jiri and Hobza, Pavel,
Title = Forces of attraction,
Journal = ORGANIC \& BIOMOLECULAR CHEMISTRY,
Year = 2007,
Volume = 5,
Number = 17,
Pages = B71,
ISSN = 1477-0520,
Unique-ID = ISI:000248731600008,
methods structure and binding energies?," in COMPUTATION IN MODERN SCIENCE AND ENGINEERING VOL 2, PTS A AND B, 2007, pp. 1244-1247.
[Bibtex]
@inproceedings ISI:000252602900306,
Author = Kabelac, Martin and Valdes, Haydee and Sherer, Edward C. and Cramer,
Christopher J. and Hobza, Pavel,
Editor = Simos, TE and Maroulis, G,
Title = New MP2 database of nucleic acid base trimers: How well reproduce DFT
methods structure and binding energies?,
Booktitle = COMPUTATION IN MODERN SCIENCE AND ENGINEERING VOL 2, PTS A AND B,
Series = AIP CONFERENCE PROCEEDINGS,
Year = 2007,
Volume = 2,
Number = Part a,
Pages = 1244-1247,
Note = International Conference on Computational Methods in Science and
Engineering, Corfu, GREECE, SEP 25-30, 2007,
Organization = European Soc Computat Methods Sci \& Engn; Minist Natl Educ \& Religious
Affairs; E4 Comp Engn,
Abstract = A new database of nucleic acid base trimers has been developed that
includes 141 geometries and stabilization energies obtained at the
RI-MP2 level of theory with the TZVPP basis set. Compared to other
databases, this one includes considerably more complicated structures;
the various intermolecular interactions in the trimers are quite
heterogeneous and in particular include simultaneous hydrogen bonding
and stacking interactions, which is similar to the situation in real
biomolecules. Validation against these benchmark data is therefore a
more demanding task for approximate models, since correct descriptions
of all energy terms is unlikely to be accomplished by fortuitous
cancellations of systematic errors. The density functionals TPSS (both
with and without an empirical dispersion term), PWB6K, M05-2X, and
BH\&H, and the self-consistent charge density functional tight binding
method augmented with an empirical dispersion term (SCC-DFTB-D) were
assessed for their abilities to accurately compute structures and
energies. The best reproduction of the BSSE corrected RI-MP2
stabilization energies was achieved by the TPSS functional (TZVPP basis
set) combined with empirical dispersion; removal of the dispersion
correction leads to significantly degraded performance. The M05-2X and
PWB6K functionals performed very well in reproducing the RI-MP2
geometries, but showed a systematic moderate underestimation of the
magnitude of base stacking interactions. The SCC-DFTB-D method predicts
geometries in fair agreement with RI-MP2; given its computational
efficiency it represents a good option for initial scanning of potential
energy surfaces of biopolymers. BH\&H gives geometries of comparable
quality to the other functionals but significantly overestimates
interaction energies other than stacking. The whole database of
geometries and interaction energies of the complexes can be found on the
web page: http://www.rsc.org/suppdata/CP/b7/b707182e/index.sht,
ISSN = 0094-243X,
ISBN = 978-0-7354-0476-2,
Unique-ID = ISI:000252602900306,
... acetone complex," in COMPUTATION IN MODERN SCIENCE AND ENGINEERING VOL 2, PTS A AND B, 2007, pp. 1339-1342.
[Bibtex]
@inproceedings ISI:000252602900329,
Author = Pluhackova, Kristyna and Hobza, Pavel,
Editor = Simos, TE and Maroulis, G,
Title = Theoretical investigation of the unexpected red shift in the halothane
... acetone complex,
Booktitle = COMPUTATION IN MODERN SCIENCE AND ENGINEERING VOL 2, PTS A AND B,
Series = AIP CONFERENCE PROCEEDINGS,
Year = 2007,
Volume = 2,
Number = Part a,
Pages = 1339-1342,
Note = International Conference on Computational Methods in Science and
Engineering, Corfu, GREECE, SEP 25-30, 2007,
Organization = European Soc Computat Methods Sci \& Engn; Minist Natl Educ \& Religious
Affairs; E4 Comp Engn,
Abstract = Halothane ... acetone and fluoroform ... acetone complexes were studied
using the MP2 method with a cc-pVTZ basis set and the DFT method with
TPSS functional and a TZVP basis set. Whereas fluoroform shows a
pronounced blue shift upon complexation, halothane exhibits a small and
surprisingly red shift. To explain this we have performed the SAPT and
NBO analyses. Although the composition of the total stabilisation energy
of each complex gained different results it did not provide a
satisfactory explanation for the difference in the spectral shifts. The
origin of the difference in the shifts was interpreted to be a result of
the interplay of the hyperconjugation and rehybridisation mechanisms.
The blue-shift of the C-H stretch frequency upon complexation exhibited
by fluoroform ... acetone complex was explained by concerting of the two
above-mentioned mechanisms. On the other hand, in the halothane ...
acetone complex the hyperconjugation and rehybridisation mechanisms
compensate and it results in small red shift of the C-H stretch
frequency. ne calculated shift of the C-H stretch vibration frequencies
of halothane (+27 cm(-1)) agreed with the experimental value of +5
cm(-1).,
ISSN = 0094-243X,
ISBN = 978-0-7354-0476-2,
Unique-ID = ISI:000252602900329,
[Bibtex]
@article ISI:000248797800008,
Author = Cerny, Jiri and Hobza, Pavel,
Title = Forces of attraction,
Journal = CHEMICAL COMMUNICATIONS,
Year = 2007,
Number = 33,
Pages = B71,
ISSN = 1359-7345,
Unique-ID = ISI:000248797800008,
[Bibtex]
@article ISI:000248731300008,
Author = Cerny, Jiri and Hobza, Pavel,
Title = Forces of attraction,
Journal = DALTON TRANSACTIONS,
Year = 2007,
Number = 33,
Pages = B71,
ISSN = 1477-9226,
Unique-ID = ISI:000248731300008,
2006
and DFTB calculations," ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 232, pp. 96-COMP, 2006.
[Bibtex]
@article ISI:000207781604175,
Author = Hobza, Pavel,
Title = Stabilization energies of DNA base pairs and aminoacid pairs: WFT, DFT
and DFTB calculations,
Journal = ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2006,
Volume = 232,
Pages = 96-COMP,
Month = SEP 10,
ISSN = 0065-7727,
Unique-ID = ISI:000207781604175,
M. Kabelac and P. Hobza, "Na(+), Mg(2+), and Zn(2+) binding to all tautomers of adenine, cytosine,
and thymine and the eight most stable keto/enol tautomers of guanine: A
correlated ab initio quantum chemical study," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 110, iss. 29, pp. 14515-14523, 2006.
[Bibtex]
@article ISI:000239141800076,
Author = Kabelac, Martin and Hobza, Pavel,
Title = Na(+), Mg(2+), and Zn(2+) binding to all tautomers of adenine, cytosine,
and thymine and the eight most stable keto/enol tautomers of guanine: A
correlated ab initio quantum chemical study,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2006,
Volume = 110,
Number = 29,
Pages = 14515-14523,
Month = JUL 27,
Abstract = Interactions of adenine, cytosine, guanine, and thymine with Na(+),
Mg(2+), and Zn(2+) cations were studied using an approximate resolution
of identity correlated second- order MP2 ( RI- MP2) method with the
TZVPP ([ 5s3p2d1f/ 3s2p1d]) basis set. All existing tautomers of
adenine, cytosine, and thymine and the eight most stable keto/ enol
tautomers of guanine were considered. Cations bind mostly in a bidentate
manner, and stabilization energies of these complexes are larger than
those in the case when cations bind in a unidentate manner. The cation
center dot center dot center dot Y ( Y equal to N or O) distances for
divalent metals are shorter than those for Na(+) and for Zn(2+) are
mostly shorter than the Mg(2+), Y distance. The intermolecular distances
between the cation and the base for complexes containing adenine and
cytosine are systematically shorter than those for complexes containing
guanine and thymine. Only for cytosine the canonical keto/ amino
tautomer structure with ions represents the global minimum. For guanine,
the metalated canonical form is again the most stable, but its
stabilization energy is within less than 5\% of the stabilization
energies of the two other rare tautomers, which indicates that the
canonical form and these two rare tautomers could coexist. The canonical
structures of adenine and thymine in the presence of ions are
considerably less stable ( by more than 10\%) than the complexes of the
rare tautomers. It can be concluded that the interaction of Na(+),
Mg(2+), and Zn(2+) cations with cytosine in the gas phase will not
induce the change of the canonical form to the rare tautomeric form. In
the case of isolated guanine, the equilibrium of the canonical form with
rare tautomers can be found. For isolated adenine and thymine the
presence of rare tautomers is highly probable.,
DOI = 10.1021/jp062249u,
ISSN = 1520-6106,
Unique-ID = ISI:000239141800076,
W. Zierkiewicz, D. Michalska, J. Cerny, and P. Hobza, "Cation-pi complexes between alkali metal cation and
para-halogenophenols. Structures, binding energies and thermodynamic
properties: DFT study and CCSD(T) complete basis set limit calculations," MOLECULAR PHYSICS, vol. 104, iss. 13-14, pp. 2317-2325, 2006.
[Bibtex]
@article ISI:000238612500028,
Author = Zierkiewicz, W and Michalska, D and Cerny, J and Hobza, P,
Title = Cation-pi complexes between alkali metal cation and
para-halogenophenols. Structures, binding energies and thermodynamic
properties: DFT study and CCSD(T) complete basis set limit calculations,
Journal = MOLECULAR PHYSICS,
Year = 2006,
Volume = 104,
Number = 13-14,
Pages = 2317-2325,
Month = JUL 10,
Abstract = Density functional (B3LYP) studies have been undertaken on the molecular
structures, binding energies and thermodynamic properties of pi type
complexes formed by alkali metal cations (Li+, Na+, K+) with phenol
(Ph), and para-halogenophenols, p-XPh (X = F, Cl, Br). The performance
of the DFT procedure for M+ (phenol) complexes was verified by
performing the complete basis set limit calculations at the CCSD(T)
level. The DFT stabilization energies for the Li+ and Na+ complexes
agree well with earlier accurately determined energies, while those for
K+ complexes are underestimated by about 30\%. This is explained by the
role of electron correlation effects (mainly dispersion energy), which
are neglected at the DFT level. The effect of the halogen
para-substituent on the strength of cation binding to the pi face of the
phenol ring is discussed. The calculated Gibbs free energy (Delta G) has
revealed that all the investigated complexes are stable under standard
conditions. Results show that the binding energies of these complexes
vary in the range from -36.8 to -11.5 kcal/mol. Natural Bond Orbital
(NBO) analysis has provided detailed insight into the nature of the
electronic interactions in these systems.,
DOI = 10.1080/00268970600652839,
ISSN = 0026-8976,
Unique-ID = ISI:000238612500028,
P. Dobes, M. Otyepka, M. Strnad, and P. Hobza, "Interaction energies for the purine inhibitor roscovitine with
cyclin-dependent kinase 2: Correlated ab initio quantum-chemical, DFT
and empirical calculations," CHEMISTRY-A EUROPEAN JOURNAL, vol. 12, iss. 16, pp. 4297-4304, 2006.
[Bibtex]
@article ISI:000238032400009,
Author = Dobes, P and Otyepka, M and Strnad, M and Hobza, P,
Title = Interaction energies for the purine inhibitor roscovitine with
cyclin-dependent kinase 2: Correlated ab initio quantum-chemical, DFT
and empirical calculations,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2006,
Volume = 12,
Number = 16,
Pages = 4297-4304,
Month = MAY 24,
Abstract = The interaction between roscovitine and cyclin-dependent kinase 2 (cdk2)
was investigated by performing correlated ab initio quantum-chemical
calculations. The whole protein was fragmented into smaller systems
consisting of one or a few amino acids, and the interaction energies of
these fragments with roscovitine were determined by using the MP2 method
with the extended aug-cc-pVDZ basis set. For selected complexes, the
complete basis set limit MP2 interaction energies, as well as the
coupled-cluster corrections with inclusion of single, double and
noninteractive triples contributions [CCSD(T)], were also evaluated.
The energies of interaction between roscovitine and small fragments and
between roscovitine and substantial sections of protein (722 atoms) were
also computed by using density-functional tight-binding methods covering
dispersion energy (DFTB-D) and the Cornell empirical potential. Total
stabilisation energy originates predominantly from dispersion energy and
methods that do not account for the dispersion energy cannot, therefore,
be recommended for the study of protein-inhibitor interactions. The
Cornell empirical potential describes reasonably well the interaction
between roscovitine and protein; therefore, this method can be applied
in future thermodynamic calculations. A limited number of amino acid
residues contribute significantly to the binding of roscovitine and
cdk2, whereas a rather large number of amino acids make a negligible
contribution.,
DOI = 10.1002/chem.200501269,
ISSN = 0947-6539,
Unique-ID = ISI:000238032400009,
J. Fanfrlik, M. Lepsik, D. Horinek, Z. Havlas, and P. Hobza, "Interaction of carboranes with biomolecules: Formation of dihydrogen
bonds," CHEMPHYSCHEM, vol. 7, iss. 5, pp. 1100-1105, 2006.
[Bibtex]
@article ISI:000237836700021,
Author = Fanfrlik, J and Lepsik, M and Horinek, D and Havlas, Z and Hobza, P,
Title = Interaction of carboranes with biomolecules: Formation of dihydrogen
bonds,
Journal = CHEMPHYSCHEM,
Year = 2006,
Volume = 7,
Number = 5,
Pages = 1100-1105,
Month = MAY 12,
Abstract = Noncovalent interactions of the polyhedral corborone
1-corbacloso-dodecaborone (CB11H12)(-) with building blocks of
biomolecules, modelled by glycine (GLY), serine (SER), phenylalanine
(PHE), glutamic acid (GLU), lysine (LYS) and arginine (ARG), were
investigated in vacua by molecular dynamics simulations with the UFF
empirical potential. Selected structures were further studied by
accurate ob initio quantum chemical procedures. Interactions with a
peptide bond (GLY-SER dipeptide) and a nucleic acid building block
(guanine) were also considered. The RESP and NPA charges of carboranes
and small model systems are compared and their use is discussed. The
dominant interaction between carboranes and biomolecules is the
formation of unconventional proton-hydride hydrogen bonds (dihydrogen
bonds) characterized by a short distance between hydrogen atoms (as
close as 1.8 angstrom) and on average strength in the range of 4.2-5.8
kcal mol(-1). The total stabilization energy of complexes investigated
is rather large, and the largest value (approximate to 15 kcal mol(-1))
was found for the carborane complexes with ARG and the GLY-SER
dipeptide. These interactions are ubiquitous under geometrical
constraints influencing the strength of the interaction. The carborane
forms dihydrogen bonds with biomolecules preferably with the hydrogen
atoms of its lower hemisphere (i.e. the part of the cage opposite to the
carbon atom). These two geometrical factors can be used to explain the
specificity of inhibition of HIV protease by carborones.,
DOI = 10.1002/cphc.200500648,
ISSN = 1439-4235,
Unique-ID = ISI:000237836700021,
D. Reha, M. Hocek, and P. Hobza, "Exceptional thermodynamic stability of DNA duplexes modified by nonpolar
base analogues is due to increased stacking interactions and favorable
solvation: Correlated ab initio calculations and molecular dynamics
simulations," CHEMISTRY-A EUROPEAN JOURNAL, vol. 12, iss. 13, pp. 3587-3595, 2006.
[Bibtex]
@article ISI:000237177800017,
Author = Reha, D and Hocek, M and Hobza, P,
Title = Exceptional thermodynamic stability of DNA duplexes modified by nonpolar
base analogues is due to increased stacking interactions and favorable
solvation: Correlated ab initio calculations and molecular dynamics
simulations,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2006,
Volume = 12,
Number = 13,
Pages = 3587-3595,
Month = APR 14,
Abstract = The geometries of DNA hexamer (5'-GGAACC-3') and DNA 13-mer
(5'-GCGTACACA7FGCG-3') have been determined by molecular dynamics (MD)
simulations using an empirical force field. The central canonical base
pair was replaced by a pair of nonpolar base analogues, 2,2'-bipyridyl
and 3-methylisocarbostyril. The stabilization energy of the model system
(model A) consisting of a central base pair (base-analogue pair) and two
neighboring base pairs was determined by the RI-MP2 method using an
extended aug-cc-pVDZ basis set. The geometry of the model was averaged
from structures determined by MD simulations. The role of the solvent
was covered by the COSMO continuum solvent model and calculations were
performed for a larger model system (model 13) which also contained a
sugar-phosphate backbone. The total stabilization energies of the
unperturbed system and the system perturbed by a base-analogue pair
(model A) were comparable to the stability of both duplexes
experimentally determined. This is due to large stacking interaction
energy of the base-analogue self-pair which compensates for the missing
hydrogen-bonding energy of the replaced adenine...thymine base pair. The
selectivity of the base-analogue pair was reproduced (model 13) when
their desolvation energy was included with the interaction energy of
both strands determined by the approximate SCC-DF-FB-D method.,
DOI = 10.1002/chem.200501126,
ISSN = 0947-6539,
Unique-ID = ISI:000237177800017,
H. Valdes, D. Reha, and P. Hobza, "Structure of isolated tryptophyl-glycine dipeptide and
tryptophyl-glycyl-glycine tripeptide: Ab initio SCC-DFTB-D molecular
dynamics simulations and high-level correlated ab initio quantum
chemical calculations," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 110, iss. 12, pp. 6385-6396, 2006.
[Bibtex]
@article ISI:000236407400075,
Author = Valdes, H and Reha, D and Hobza, P,
Title = Structure of isolated tryptophyl-glycine dipeptide and
tryptophyl-glycyl-glycine tripeptide: Ab initio SCC-DFTB-D molecular
dynamics simulations and high-level correlated ab initio quantum
chemical calculations,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2006,
Volume = 110,
Number = 12,
Pages = 6385-6396,
Month = MAR 30,
Abstract = The tryptophyl-glycine (Trp-Gly) and tryptophyl-glycyl-glycine
(Trp-Gly-Gly) peptides have been studied by means of molecular dynamic
simulations combined with high-level correlated ab initio quantum
chemical and statistical thermodynamic calculations. The lowest energy
conformers were localized in the free energy surface. The Structures of
the different Trp-Gly and Trp-Gly-Gly conformers coexisting in the gas
phase have been for the first time reported and their scaled theoretical
IR spectra unambiguously assigned and compared with previous gas-phase
experimental results. Common geometrical features have been
systematically observed for the sequence Trp, Trp-Gly, and Trp-Gly-Gly.
In addition. the peptide backbone of Trp-Gly-Gly has been compared with
that of the previously studied Phe-Gly-Gly (Reha, D. et. al. Chem. Eur.
J. 2005, 11, 6803). From the observed systematic Structural behavior
between these peptide analogues, it is expected that the gas-phase
conformers of other similar aromatic small peptides would present
equivalent geometries. The DFT methodology failed to describe the
potential energy surface of the studied peptides since the London
dispersion energy (not covered in DFT) plays a significant role in the
stabilization of most stable conformers.,
DOI = 10.1021/jp057425y,
ISSN = 1520-6106,
Unique-ID = ISI:000236407400075,
J. Sponer, P. Jurecka, I. Marchan, F. Luque, M. Orozco, and P. Hobza, "Nature of base stacking: Reference quantum-chemical stacking energies in
ten unique B-DNA base-pair steps," CHEMISTRY-A EUROPEAN JOURNAL, vol. 12, iss. 10, pp. 2854-2865, 2006.
[Bibtex]
@article ISI:000236483400022,
Author = Sponer, J and Jurecka, P and Marchan, I and Luque, FJ and Orozco, M and
Hobza, P,
Title = Nature of base stacking: Reference quantum-chemical stacking energies in
ten unique B-DNA base-pair steps,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2006,
Volume = 12,
Number = 10,
Pages = 2854-2865,
Month = MAR 20,
Abstract = Base-stacking energies in ten unique B-DNA base-pair steps and some
other arrangements were evaluated by the second-order Moller-Plesset
(MP2) method, complete basis set (CBS) extrapolation, and correction for
triple (T) electron-correlation contributions. The CBS(T) calculations
were compared with decade-old MP2/6-31G*(0.25) reference data and
AMBER force field. The new calculations show modest increases in
stacking stabilization compared to the MP2/6-31G*(0.25) data and
surprisingly large sequence-dependent variation of stacking energies.
The absolute force-field values are in better agreement with the new
reference data, while relative discrepancies between quantum-chemical
(QM) and force-field values increase modestly. Nevertheless, the force
field provides good qualitative description of stacking, and there is no
need to introduce additional pair-additive electrostatic terms, such as
distributed multipoles or out-of-plane charges. There is a rather
surprising difference of about 0.1 angstrom between the vertical
separation of base pairs predicted by quantum chemistry and derived from
crystal structures. Evaluations of different local arrangements of the
5'-CG-3' step indicate a sensitivity of the relative stacking energies
to the level of calculation. Thus, describing quantitative relations
between local DNA geometrical variations and stacking may be more
complicated than usually assumed. The reference calculations are
complemented by continuum-solvent assessment of solvent-screening
effects.,
DOI = 10.1002/chem.200501239,
ISSN = 0947-6539,
Unique-ID = ISI:000236483400022,
V. Spirko and P. Hobza, "Theoretical investigations into the blue-shifting hydrogen bond in
benzene complexes," CHEMPHYSCHEM, vol. 7, iss. 3, pp. 640-643, 2006.
[Bibtex]
@article ISI:000236300600016,
Author = Spirko, V and Hobza, P,
Title = Theoretical investigations into the blue-shifting hydrogen bond in
benzene complexes,
Journal = CHEMPHYSCHEM,
Year = 2006,
Volume = 7,
Number = 3,
Pages = 640-643,
Month = MAR 13,
Abstract = The benzene(...)X complexes (X=benzene, antracene, ovalene) were
optimised at the MP2/6-31G** level with the C-2v symmetry of the
complex and planarity of the proton acceptor being preserved. The
resulting stabilisation energies amount to 1.2, 2.3 and 2.9 kcal
mol(-1), and the C-H bond of the proton donor is contracted by 0.0035,
0.0052 and 0.0055 A, respectively. The contraction is connected with a
blue-shift of the C-H stretch vibration frequency. A two-dimensional
anharmonic vibration treatment based on a MP2/6-31G** potential
energy surface yields the following blue shifts for the complexes
studied: 28, 42 and 43 cm(-1) . The dominant attraction in the complexes
is London dispersion, while the attractive contribution from
electrostatic quadrupole-quadrupole interactions is considerably
smaller.,
DOI = 10.1002/cphc.200500565,
ISSN = 1439-4235,
Unique-ID = ISI:000236300600016,
M. Otyepka, P. Sklenovsky, D. Horinek, T. Kubar, and P. Hobza, "How the stabilization of INK4 tumor suppressor 3D structure evaluated by
quantum chemical and molecular mechanics calculations corresponds well
with experimental results: Interplay of association enthalpy, entropy,
and solvation effects," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 110, iss. 9, pp. 4423-4429, 2006.
[Bibtex]
@article ISI:000235944500084,
Author = Otyepka, M and Sklenovsky, P and Horinek, D and Kubar, T and Hobza, P,
Title = How the stabilization of INK4 tumor suppressor 3D structure evaluated by
quantum chemical and molecular mechanics calculations corresponds well
with experimental results: Interplay of association enthalpy, entropy,
and solvation effects,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2006,
Volume = 110,
Number = 9,
Pages = 4423-4429,
Month = MAR 9,
Abstract = The folding free energy of the INK4c tumor suppressor core, consisting
of 10 helices, was determined as the sum of gas-phase interaction
enthalpy, gas-phase interaction entropy, and dehydration and hydration
free energy. The interaction energy and the hydration free energy were
determined using the nonempirical density functional theory (DFT)
method, augmented by a dispersion-energy correction term, the
semiempirical density-functional tight-binding method covering the
dispersion energy, and the density functional theory/conductor-like
screening model (DFT/COSMO) procedure, whereas the interaction entropy
was calculated with the empirical Cornell et al. force field.
Alternatively, all contributions were evaluated consistently using
empirical methods. All the values of the interaction energy of helix
pairs are stabilizing, and the dominant stabilizing terms stem from the
London dispersion energy and, in the case of charged systems, the
electrostatic energy. The stabilization energy of the core, determined
as the difference of the energy of the core and 10 separate helices,
amounts to similar to 450 kcal/mol. Systematically, the difference in
the hydration free energy of a helix pair and its separate components is
smaller in magnitude than the interaction energy, and it is negative for
some pairs while positive for others. The average total free energy of a
core formation amounts to -29.6 kcal/mol (yielded by scaled
quantum-chemical methods) and + 13.9 kcal/mol (resulting from empirical
methods). These values are considerably smaller than their single
components, which are dominated by the interaction energy. The
computationally predicted interval encloses the experimental value of
the folding free energy (-2.8 kcal/mol).,
DOI = 10.1021/jp056890s,
ISSN = 1520-6106,
Unique-ID = ISI:000235944500084,
L. Zendlova, P. Hobza, and M. Kabelac, "Potential energy surfaces of the microhydrated guanine(...)cytosine base
pair and its methylated analogue," CHEMPHYSCHEM, vol. 7, iss. 2, pp. 439-447, 2006.
[Bibtex]
@article ISI:000235404300021,
Author = Zendlova, L and Hobza, P and Kabelac, M,
Title = Potential energy surfaces of the microhydrated guanine(...)cytosine base
pair and its methylated analogue,
Journal = CHEMPHYSCHEM,
Year = 2006,
Volume = 7,
Number = 2,
Pages = 439-447,
Month = FEB 13,
Abstract = A complete scan of the potential and free-energy surfaces of
monohydrated and dihydrated guanine cytosine and
9-methylguanine...7-methylcytosine base pairs was realized by the
molecular dynomics/quenching technique using the force field of Cornell
et al. implemented in the AMBER7 program. The most stable and populated
structures localized were further fully reoptimized at the correlated ab
initio level employing the resolution of identity Moller-Plesset method
with a large basis set. A systematic study of microhydration of these
systems using a high-level correlated ab initio approach is presented
for the first time. The different behavior of guanine...cytosine and
adenine...thymine complexes is also discussed. These studies of nucleic
acid base pairs are important for finding binding sites of water
molecules around bases and for better understanding of the influence of
the solvent on the stability of the structure of DNA.,
DOI = 10.1002/cphc.200500311,
ISSN = 1439-4235,
Unique-ID = ISI:000235404300021,
P. Jurecka, J. Sponer, J. Cerny, and P. Hobza, "Benchmark database of accurate (MP2 and CCSD(T) complete basis set
limit) interaction energies of small model complexes, DNA base pairs,
and amino acid pairs," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 8, iss. 17, pp. 1985-1993, 2006.
[Bibtex]
@article ISI:000236970300001,
Author = Jurecka, P and Sponer, J and Cerny, J and Hobza, P,
Title = Benchmark database of accurate (MP2 and CCSD(T) complete basis set
limit) interaction energies of small model complexes, DNA base pairs,
and amino acid pairs,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2006,
Volume = 8,
Number = 17,
Pages = 1985-1993,
Abstract = MP2 and CCSD(T) complete basis set (CBS) limit interaction energies and
geometries for more than 100 DNA base pairs, amino acid pairs and model
complexes are for the first time presented together. Extrapolation to
the CBS limit is done by using two-point extrapolation methods and
different basis sets (aug-cc-pVDZ-aug-cc-pVTZ, aug-cc-pVTZ-aug-cc-pVQZ,
cc-pVTZ-ccp-VQZ) are utilized. The CCSD(T) correction term, determined
as a difference between CCSD( T) and MP2 interaction energies, is
evaluated with smaller basis sets (6-31G** and cc-pVDZ). Two sets of
complex geometries were used, optimized or experimental ones. The
JSCH-2005 benchmark set, which is now available to the chemical
community, can be used for testing lower-level computational methods.
For the first screening the smaller training set (S22) containing 22
model complexes can be recommended. In this case larger basis sets were
used for extrapolation to the CBS limit and also CCSD(T) and
counterpoise-corrected MP2 optimized geometries were sometimes adopted.,
DOI = 10.1039/b600027d,
ISSN = 1463-9076,
Unique-ID = ISI:000236970300001,
J. Cerny, V. Spirko, M. Mons, P. Hobza, and D. Nachtigallova, "Theoretical study of the ground and excited states of 7-methyl guanine
and 9-methyl guanine: comparison with experiment," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 8, iss. 26, pp. 3059-3065, 2006.
[Bibtex]
@article ISI:000238617000002,
Author = Cerny, J and Spirko, V and Mons, M and Hobza, P and Nachtigallova, D,
Title = Theoretical study of the ground and excited states of 7-methyl guanine
and 9-methyl guanine: comparison with experiment,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2006,
Volume = 8,
Number = 26,
Pages = 3059-3065,
Abstract = The keto-enol tautomerization of 7-methyl-guanine and 9-methyl-guanine
in the excited state was investigated using the time-dependent DFT
(TDDFT) method. For both species, the potential energy surfaces of the
ground state and two lowest singlet excited states (due to pi -> pi*
and n -> pi* transitions) have been investigated and their features
discussed in terms of consequences on the excited state dynamics. The
findings suggest that, for both species, the state due to the n -> pi*
transition, suspected to be an intermediate in the excited state
deactivation, exhibits two minima with the second minimum characterized
by an elongated N1-H distance. This structure, intermediate between enol
and keto tautomers, might play a role in the excited state relaxation.
The existence of this second well, however, is observed in both 7- and
9-methyl-guanine, which suggests that it cannot account alone for the
different photophysical behavior of these species.,
DOI = 10.1039/b601629d,
ISSN = 1463-9076,
Unique-ID = ISI:000238617000002,
E. Muchova, V. Spirko, P. Hobza, and D. Nachtigallova, "Theoretical study of photoacidity of HCN: the effect of complexation
with water," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 8, iss. 42, pp. 4866-4873, 2006.
[Bibtex]
@article ISI:000241526600005,
Author = Muchova, Eva and Spirko, Vladimir and Hobza, Pavel and Nachtigallova,
Dana,
Title = Theoretical study of photoacidity of HCN: the effect of complexation
with water,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2006,
Volume = 8,
Number = 42,
Pages = 4866-4873,
Abstract = The character of the hydrogen bonding and the excited state proton
transfer (ESPT) in the model system (HCNH2O)-H-... is investigated. The
PES of the two lowest excited states of the (H2OHCN)-H-... complex was
calculated using the CASPT2 method. The nonadiabatic coupling of the two
states of the (pi -> pi *) and (pi -> sigma*) character is
responsible for the excited state proton/hydrogen transfer. Compared to
the ground state, the barrier for this process is significantly smaller.
An increased number of water molecules in the complex with cyclic
hydrogen-bonded network causes a large blue shift of the state of the
(pi -> sigma*) character. The question of the dissociation of the
complex in its excited state is also addressed.,
DOI = 10.1039/b610001e,
ISSN = 1463-9076,
Unique-ID = ISI:000241526600005,
P. Hobza, R. Zahradnik, and K. Muller-Dethlefs, "The world of non-covalent interactions: 2006," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 71, iss. 4, pp. 443-531, 2006.
[Bibtex]
@article ISI:000236938200001,
Author = Hobza, P and Zahradnik, R and Muller-Dethlefs, K,
Title = The world of non-covalent interactions: 2006,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2006,
Volume = 71,
Number = 4,
Pages = 443-531,
Abstract = The review focusses on the fundamental importance of non-covalent
interactions in nature by illustrating specific examples from chemistry,
physics and the biosciences. Laser spectroscopic methods and both ab
initio and molecular modelling procedures used for the study of
non-covalent interactions in molecular clusters are briefly outlined.
The role of structure and geometry, stabilization energy, potential and
free energy surfaces for molecular clusters is extensively discussed in
the light of the most advanced ab initio computational results for the
CCSD(T) method, extrapolated to the CBS limit. The most important types
of non-covalent complexes are classified and several small and medium
size non-covalent systems, including H-bonded and improper H-bonded
complexes, nucleic acid base pairs, and peptides and proteins are
discussed with some detail. Finally, we evaluate the interpretation of
experimental results in comparison with state of the art theoretical
models: this is illustrated for phenol... Ar, the benzene dimer and
nucleic acid base pairs. A review with 270 references.,
DOI = 10.1135/cccc20060443,
ISSN = 0010-0765,
Unique-ID = ISI:000236938200001,
T. Kubar, M. Hanus, F. Ryjacek, and P. Hobza, "Binding of cationic and neutral phenanthridine Intercalators to a DNA
oligomer is controlled by dispersion energy: Quantum chemical
calculations and molecular mechanics simulations," CHEMISTRY-A EUROPEAN JOURNAL, vol. 12, iss. 1, pp. 280-290, 2006.
[Bibtex]
@article ISI:000234236400025,
Author = Kubar, T and Hanus, M and Ryjacek, F and Hobza, P,
Title = Binding of cationic and neutral phenanthridine Intercalators to a DNA
oligomer is controlled by dispersion energy: Quantum chemical
calculations and molecular mechanics simulations,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2006,
Volume = 12,
Number = 1,
Pages = 280-290,
Abstract = Correlated ab initio as well as semiempirical quantum chemical
calculations and molecular dynamics simulations were used to study the
intercalation of cationic ethidium, cationic
5-ethyl-6-phenylphenanthridinium and uncharged
3,8-diamino-6-phenylphenanthridine to DNA. The stabilization energy of
the cationic intercalators is considerably larger than that of the
uncharged one. The dominant energy contribution with all intercalators
is represented by dispersion energy. In the case of the cationic
intercalators, the electrostatic and charge-transfer terms are also
important. The Delta G of ethidium intercalation to DNA was estimated at
-4.5 kcal mol(-1) and this value agrees well with the experimental
result. Of six contributions to the final free energy, the interaction
energy value is crucial. The intercalation process is governed by the
non-covalent stacking (including charge -transfer) interaction while the
hydrogen bonding between the ethidium amino groups and the DNA backbone
is less important. This is confirmed by the evaluation of the
interaction energy as well as by the calculation of the free energy
change. The intercalation affects the macroscopic properties of DNA in
terms of its flexibility. This explains the easier entry of another
intercalator molecule in the vicinity of an existing intercalation site.,
DOI = 10.1002/chem.200500725,
ISSN = 0947-6539,
Unique-ID = ISI:000234236400025,
level correlated ab initio data with experiment," in RECENT PROGRESS IN COMPUTATIONAL SCIENCES AND ENGINEERING, VOLS 7A AND
7B, 2006, pp. 1493-1496.
[Bibtex]
@inproceedings ISI:000254378800376,
Author = Kabelac, Martin and Sherer, Edward C. and Cramer, Christopher J. and
Hobza, Pavel,
Editor = Simos, T and Maroulis, G,
Title = Trimers of nucleic acid bases: Comparison of empirical, DFT and high
level correlated ab initio data with experiment,
Booktitle = RECENT PROGRESS IN COMPUTATIONAL SCIENCES AND ENGINEERING, VOLS 7A AND
7B,
Series = LECTURE SERIES ON COMPUTER AND COMPUTATIONAL SCIENCES,
Year = 2006,
Volume = 7A-B,
Pages = 1493-1496,
Note = International Conference on Computational Methods in Science and
Engineering, Chania, GREECE, OCT 27-NOV 01, 2006,
Abstract = A complete scan of the potential energy surfaces for selected DNA base
trimers has been performed by a molecular dynamics/quenching technique
using the force field of Cornell et aL implemented in the AMBER7
program. The resulting most stable/populated structures were then
reoptimized at a correlated ab initio level employing Resolution of the
Identity Moller-Plesset second-order perturbation theory (RI-MP2). We
show that prior experimental and theoretical interpretations were
incorrect in assuming that the most stable structures of the methylated
trimers correspond to planar systems characterized by cyclic
intermolecular hydrogen bonding. We found that stacked structures of two
bases with the third base in a T-shape arrangement are the global minima
in all of the methylated systems, The high-level geometries and
interaction energies computed for the trimers serve also as a reference
for the testing of recently developed DFT functionals with respect to
their ability to describe correctly the balance between electrostatic
and dispersion contributions that binds these trimers together. The
recently reported M052X functional with a polarized triple-zeta basis
set predicts 11 uracil trimer interaction energies with a
root-mean-square error of 2.3 kcal/mol compared to our most highly
correlated ab initio level of theory.,
ISSN = 1573-4196,
ISBN = 978-90-04-15542-8,
Unique-ID = ISI:000254378800376,
[Bibtex]
@article ISI:000241081400001,
Author = Bohacek, Krystof and Hobza, Pavel,
Title = Theme: pre-socratic philosophy,
Journal = FILOSOFICKY CASOPIS,
Year = 2006,
Volume = 54,
Number = 3,
Pages = 322-323,
ISSN = 0015-1831,
Unique-ID = ISI:000241081400001,
[Bibtex]
@article ISI:000241081400004,
Author = Hobza, Jr., Pavel,
Title = The conception of the earth in Anaximander's cosmology,
Journal = FILOSOFICKY CASOPIS,
Year = 2006,
Volume = 54,
Number = 3,
Pages = 381-392,
Abstract = In reconstructing Anaximander's cosmological opinions it is important to
grasp how Anaximander conceives of the earth. The problem is not its
position at the centre of the universe, but rather how it remains
there-what holds it in place. According to Aristotle, Anaximander
explained how it kept its place by its equal distance from the limits of
the universe: that is, by its symmetrical or equilibrial position at the
centre of the universe. Despite this geometrical conception being
commonly accepted, closer analysis shows that Aristotle's report is
really a biased interpretation and that the real reason for the
remaining in place of Anaximander's earth is its hovering on air.
Evidence of this is partly given by doxographic reports which speak of
Anaximander's earth as hovering (meteoros), and partly by its shape
being flat, since its flatness enabled it to rest on air.,
ISSN = 0015-1831,
Unique-ID = ISI:000241081400004,
[Bibtex]
@article ISI:000243884500009,
Author = Hobza, Jr., Pavel,
Title = The oral character of Greek culture,
Journal = FILOSOFICKY CASOPIS,
Year = 2006,
Volume = 54,
Number = 6,
Pages = 905-919,
ISSN = 0015-1831,
Unique-ID = ISI:000243884500009,
2005
D. Reha, H. Valdes, J. Vondrasek, P. Hobza, A. Abu-Riziq, B. Crews, and M. de Vries, "Structure and IR spectrum of phenylalanyl-glycyl-glycine tripetide in
the gas-phase: IR/UV experiments, ab initio quantum chemical
calculations, and molecular dynamic Simulations," CHEMISTRY-A EUROPEAN JOURNAL, vol. 11, iss. 23, pp. 6803-6817, 2005.
[Bibtex]
@article ISI:000233508800002,
Author = Reha, D and Valdes, H and Vondrasek, J and Hobza, P and Abu-Riziq, A and
Crews, B and de Vries, MS,
Title = Structure and IR spectrum of phenylalanyl-glycyl-glycine tripetide in
the gas-phase: IR/UV experiments, ab initio quantum chemical
calculations, and molecular dynamic Simulations,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2005,
Volume = 11,
Number = 23,
Pages = 6803-6817,
Month = NOV 18,
Abstract = We investigated the potential-energy surface (PES) of the
phenylalanyl-glycyl-glycine tripeptide in the gas phase by means of
IR/UV double-resonance spectroscopy, and quantum chemical and
statistical thermodynamic calculations. Experimentally, we observed four
conformational structures and we recorded their IR spectra in the
spectral region of 3000-4000 cm(-1). Computationally, we investigated
the PES by a combination of molecular dynamics/quenching procedures with
high-level correlated ab initio calculations. We found that neither
empirical potentials nor various DFT functionals provide satisfactory
results. On the other hand, the approximative DFT method covering the
dispersion energy yields a reliable set of the most stable structures,
which we subsequently investigated with an accurate, correlated ab
initio treatment. The global minimum contains three moderately strong
intramolecular hydrogen bonds and is mainly stabilized by London
dispersion forces between the phenyl ring, the carboxylic acid group,
and various peptide bonds. A proper description of the last type of
interaction requires accurate correlated ab initio calculations,
including the complete basis set limit of the MP2 method and CCSD(T)
correction terms. Since in our beam experiments the conformations are
frozen by cooling from a higher temperature, it is necessary to localize
the most stable structures on the free-energy surface rather than on the
PES. We used two different procedures (rigid rotor/harmonic
oscillator/ideal gas approximation based on ab initio characteristics
and evaluation of relative populations from the molecular dynamic
simulations using the AMBER potential) and both yield four structures,
the global minimum and three local minima. These four structures were
among the 15 most energetically stable structures obtained from accurate
ab initio optimization. The calculated IR spectra for these four
structures agree well with the experimental frequencies, which validates
the localization procedure.,
DOI = 10.1002/chem.200500465,
ISSN = 0947-6539,
Unique-ID = ISI:000233508800002,
complexes of HCN ... H20 in its ground and electronically excited states," ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 230, pp. 281-PHYS, 2005.
[Bibtex]
@article ISI:000236797305739,
Author = Mrazkova, E and Nachtigallova, D and Hobza, P,
Title = Theoretical study of potential energy surfaces of hydrogen bonded
complexes of HCN ... H20 in its ground and electronically excited states,
Journal = ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2005,
Volume = 230,
Pages = 281-PHYS,
Month = AUG 28,
Note = 230th National Meeting of the American-Chemical-Society, Washington, DC,
AUG 28-SEP 01, 2005,
ISSN = 0065-7727,
Unique-ID = ISI:000236797305739,
A. Perez, J. Sponer, P. Jurecka, P. Hobza, F. Luque, and M. Orozco, "Are the hydrogen bonds of RNA (A center dot U) stronger than those of
DNA (A center dot T)? A quantum mechanics study," CHEMISTRY-A EUROPEAN JOURNAL, vol. 11, iss. 17, pp. 5062-5066, 2005.
[Bibtex]
@article ISI:000231556400021,
Author = Perez, A and Sponer, J and Jurecka, P and Hobza, P and Luque, FJ and
Orozco, M,
Title = Are the hydrogen bonds of RNA (A center dot U) stronger than those of
DNA (A center dot T)? A quantum mechanics study,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2005,
Volume = 11,
Number = 17,
Pages = 5062-5066,
Month = AUG 19,
Abstract = The intrinsic stability of Watson-Crick d(A(.)T) and r(A(.)U) hydrogen
bonds was analyzed by employing a variety of quantum-mechanical
techniques, such as energy calculations, determination of reactivity
indexes, and analysis of electron density topology. The analyses were
performed not only for equilibrium gas-phase geometries, but also on
hundreds of conformations derived from molecular dynamics (MD) and
database analysis. None of our results support the idea that r(A(.)U)
hydrogen bonds are intrinsically more stable than those of d(A(.)T).
Instead, our data are in accordance with the traditional view that the
greater stability of RNA relative to DNA is attributable to a variety of
effects (e.g., stacking, sugar puckering, solvation) rather than to a
significant difference in the hydrogen bonding of DNA and RNA base
pairs.,
DOI = 10.1002/chem.200500255,
ISSN = 0947-6539,
Unique-ID = ISI:000231556400021,
B. Brauer, R. Gerber, M. Kabelac, P. Hobza, J. Bakker, A. Riziq, and M. de Vries, "Vibrational spectroscopy of the G center dot center dot center dot C
base pair: Experiment, harmonic and anharmonic calculations, and the
nature of the anharmonic couplings," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 109, iss. 31, pp. 6974-6984, 2005.
[Bibtex]
@article ISI:000231042500025,
Author = Brauer, B and Gerber, RB and Kabelac, M and Hobza, P and Bakker, JM and
Riziq, AGA and de Vries, MS,
Title = Vibrational spectroscopy of the G center dot center dot center dot C
base pair: Experiment, harmonic and anharmonic calculations, and the
nature of the anharmonic couplings,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2005,
Volume = 109,
Number = 31,
Pages = 6974-6984,
Month = AUG 11,
Abstract = The results of harmonic and anharmonic frequency calculations on a
guanine-cytosine complex with an enolic structure (a tautomeric form
with cytosine in the enol form and with a hydrogen at the 7-position on
guanine) are presented and compared to gas-phase IR-UV double resonance
spectral data. Harmonic frequencies were obtained at the RI-MP2/cc-pVDZ,
RI-MP2/TZVPP, and semiempirical PM3 levels of electronic structure
theory. Anharmonic frequencies were obtained by the CC-VSCF method with
improved PM3 potential surfaces; the improved PM3 potential surfaces are
obtained from standard PM3 theory by coordinate scaling such that the
improved PM3 harmonic frequencies are the same as those computed at the
RI-MP2/cc-pVDZ level. Comparison of the data with experimental results
indicates that the average absolute percentage deviation for the methods
is 2.6\% for harmonic RI-MP2/cc-pVDZ (3.0\% with the inclusion of a
0.956 scaling factor that compensates for anharmonicity), 2.5\% for
harmonic RI-MP2/TZVPP (2.9\% with a 0.956 anharmonicity factor
included), and 2.3\% for adapted PM3 CC-VSCF; the empirical scaling
factor for the ab initio harmonic calculations improves the stretching
frequencies but decreases the accuracy of the other mode frequencies.
The agreement with experiment supports the adequacy of the improved PM3
potentials for describing the anharmonic force field of the G(...)C base
pair in the spectroscopically probed region. These results may be useful
for the prediction of the pathways of vibrational energy flow upon
excitation of this system. The anharmonic calculations indicate that
anharnionicity along single mode coordinates can be significant for
simple stretching modes. For several other cases, coupling between
different vibrational modes provides the main contribution to
anharmonicity. Examples of strongly anharmonically coupled modes are the
symmetric stretch and group torsion of the hydrogen-bonded NH2 group on
guanine, the OH stretch and torsion of the enol group on cytosine, and
the NH stretch and NH out-of-plane bend of the non-hydrogen-bonded NH
group on guanine.,
DOI = 10.1021/jp051767m,
ISSN = 1089-5639,
Unique-ID = ISI:000231042500025,
E. Mrazkova, P. Hobza, M. Bohl, D. Gauger, and W. Pohle, "Hydration-induced changes of structure and vibrational frequencies of
methylphosphocholine studied as a model of biomembrane lipids," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 109, iss. 31, pp. 15126-15134, 2005.
[Bibtex]
@article ISI:000231042800052,
Author = Mrazkova, E and Hobza, P and Bohl, M and Gauger, DR and Pohle, W,
Title = Hydration-induced changes of structure and vibrational frequencies of
methylphosphocholine studied as a model of biomembrane lipids,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2005,
Volume = 109,
Number = 31,
Pages = 15126-15134,
Month = AUG 11,
Abstract = The chemical characteristics of the polar parts of phospholipids as the
main components of biological membranes were investigated by using
infrared (IR) spectroscopy and theoretical calculations with water as a
probe molecule. The logical key molecule used in this study is
methylphosphocholine (MePC) as it is not only a representative model for
a polar lipid headgroup but itself has biological significance. Isolated
MePC forms a compact (folded) structure which is essentially stabilized
by two intramolecular C-H center dot center dot center dot O type
hydrogen bonds. At lower hydration, considerable wavenumber shifts were
revealed by IR spectroscopy: the frequencies of the (O-P-O)(-) stretches
were strongly redshifted, whereas methyl and methylene C-H and O-P-O
stretches shifted surprisingly to blue. The origin of both red- and
blueshifts was rationalized, on the basis of molecular-dynamics and
quantum-chemistry calculations. In more detail, the hydration-induced
blueshifts of C-H stretches could be shown to arise from several
origins: disruption of the intramolecular C-H center dot center dot
center dot O hydrogen bonds, formation of intermolecular C-H center dot
center dot center dot O-water H-bonds. The stepwise disruption of the
intramolecular hydrogen bonds appeared to be the main feature that
causes partial unfolding of the compact structure. However, the
transition from a folded to extended MePC structure was completed only
at high hydration. One might hypothesize that the mechanism of
hydration-driven conformational changes as described here for MePC could
be transferred to other zwitterions with relevant internal C-H center
dot center dot center dot O hydrogen bonds.,
DOI = 10.1021/jp051208f,
ISSN = 1520-6106,
Unique-ID = ISI:000231042800052,
M. Kabelac, L. Zendlova, D. Reha, and P. Hobza, "Potential energy surfaces of an adenine-thymine base pair and its
methylated analogue in the presence of one and two water molecules:
Molecular mechanics and correlated ab initio study," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 109, iss. 24, pp. 12206-12213, 2005.
[Bibtex]
@article ISI:000229867300050,
Author = Kabelac, M and Zendlova, L and Reha, D and Hobza, P,
Title = Potential energy surfaces of an adenine-thymine base pair and its
methylated analogue in the presence of one and two water molecules:
Molecular mechanics and correlated ab initio study,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2005,
Volume = 109,
Number = 24,
Pages = 12206-12213,
Month = JUN 23,
Abstract = Potential energy surfaces of morlohydrated and dihydrated
adenine-thymine and 9-methyladenine-1-methylthymine base pairs were
examined by the molecular dynamics/quenching technique using the Cornell
et al. force field (J. Am. Chem. Soc. 1995, 117, 5179). Long runs of
molecular dynarnics/quenching calculations allowed us to evaluate the
free energy surface. The most stable and populated structures found were
fully reoptimized at the correlated ab initio level employing the
resolution of identity Moller-Plesset method. A systematic study of the
base pairs' microhydration using both the empirical and the high-level
correlated ab initio approaches is presented for the first time. We show
that the occurrence of water molecules and their gradually increasing
number as well as the methylation of the bases favor stacked structures
over the planar hydrogen-bonded ones. These results based on the
correlated ab initio calculations are in the excellent agreement with
data obtained from our previous empirical potential molecular dynamics
study.,
DOI = 10.1021/jp045970d,
ISSN = 1520-6106,
Unique-ID = ISI:000229867300050,
J. Vondrasek, L. Bendova, V. Klusak, and P. Hobza, "Unexpectedly strong energy stabilization inside the hydrophobic core of
small protein rubredoxin mediated by aromatic residues: Correlated ab
initio quantum chemical calculations (vol 127, pg 2615, 2005)," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 127, iss. 22, pp. 8232, 2005.
[Bibtex]
@article ISI:000229619500063,
Author = Vondrasek, J and Bendova, L and Klusak, V and Hobza, P,
Title = Unexpectedly strong energy stabilization inside the hydrophobic core of
small protein rubredoxin mediated by aromatic residues: Correlated ab
initio quantum chemical calculations (vol 127, pg 2615, 2005),
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2005,
Volume = 127,
Number = 22,
Pages = 8232,
Month = JUN 8,
DOI = 10.1021/ja059908l,
ISSN = 0002-7863,
Unique-ID = ISI:000229619500063,
I. Daabkowska, P. Jurecka, and P. Hobza, "On geometries of stacked and H-bonded nucleic acid base pairs determined
at various DFT, MP2, and CCSD(T) levels up to the CCSD(T)/complete basis
set limit level," JOURNAL OF CHEMICAL PHYSICS, vol. 122, iss. 20, 2005.
[Bibtex]
@article ISI:000229544500033,
Author = Daabkowska, I and Jurecka, P and Hobza, P,
Title = On geometries of stacked and H-bonded nucleic acid base pairs determined
at various DFT, MP2, and CCSD(T) levels up to the CCSD(T)/complete basis
set limit level,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 2005,
Volume = 122,
Number = 20,
Month = MAY 22,
Abstract = The geometries and interaction energies of stacked and hydrogen-bonded
uracil dimers and a stacked adenine thymine pair were studied by means
of high-level quantum chemical calculations. Specifically, standard as
well as counterpoise-corrected optimizations were performed at
second-order Molller-Plesset (MP2) and coupled cluster level of theory
with single, double, and perturbative triple excitations [CCSD(T)]
levels with various basis sets up to the complete basis set limit. The
results can be summarized as follows: (i) standard geometry optimization
with small basis set (e. g., 6-31G*) provides fairly reasonable
intermolecular separation; (ii) geometry optimization with extended
basis sets at the MP2 level underestimates the intermolecular distances
compared to the reference CCSD(T) results, whereas the MP2/cc-pVTZ
counterpoise-corrected optimization agrees well with the reference
geometries and, therefore, is recommended as a next step for improving
MP2/cc-pVTZ geometries; (iii) the stabilization energy of stacked
nucleic acids base pairs depends considerably on the method used for
geometry optimization, so the use of reliable geometries, such as
counterpoise-corrected MP2/cc-pVTZ ones, is recommended; (iv) the
density functional theory methods fail completely in locating the energy
minima for stacked structures and when the geometries from MP2
calculations are used, the resulting stabilization energies are strongly
underestimated; (v) the self-consistent charges-density functional tight
binding method, with inclusion of the empirical dispersion energy,
accurately reproduces interaction energies and geometries of
dispersion-bonded (stacked) complexes; this method can thus be
recommended for prescanning the potential energy surfaces of van der
Waals complexes. (c) 2005 American Institute of Physics.,
DOI = 10.1063/1.1906205,
Article-Number = 204322,
ISSN = 0021-9606,
Unique-ID = ISI:000229544500033,
W. Zierkiewicz, P. Jurecka, and P. Hobza, "On differences between hydrogen bonding and improper blue-shifting
hydrogen bonding," CHEMPHYSCHEM, vol. 6, iss. 4, pp. 609-617, 2005.
[Bibtex]
@article ISI:000228597800009,
Author = Zierkiewicz, W and Jurecka, P and Hobza, P,
Title = On differences between hydrogen bonding and improper blue-shifting
hydrogen bonding,
Journal = CHEMPHYSCHEM,
Year = 2005,
Volume = 6,
Number = 4,
Pages = 609-617,
Month = APR,
Abstract = Twenty two hydrogen-bonded and improper blue-shifting hydrogen-bonded
complexes were studied by means of the HF MP2 and B3LYP methods using
the 6-31G(dp) and 6-311++G(dp) basis sets. In contrast to the standard H
bonding, the origin of the improper blue-shifting H bonding is still not
fully understood Contrary to a frequently presented idea, the electric
field of the Proton acceptor cannot solely explain the different
behavior of H-bonded and improper blue-shifting H-bonded complexes.
Compression of the hydrogen bond due to different attractive
forces-dispersion or electrostatics-makes an important contribution as
well. The symmetry-adapted perturbation theory (SAPT) has been utilized
to decompose the total interaction energy into physically meaningful
contributions. In the red-shifting complexes, the induction energy is
mostly larger than the dispersion energy while, in the case of
blue-shifting complexes, the situation is opposite. Dispersion as an
attractive force increases the blue shift in the blue-shifting complexes
as it compresses the H bond and, therefore, it increases the Pauli
repulsion. On the other hand, dispersion in the red-shifting complexes
increases their red shift.,
DOI = 10.1002/cphc.200400243,
ISSN = 1439-4235,
Unique-ID = ISI:000228597800009,
allylation of aldehydes with allyltrichlorosilanes and the role of
arene-arene interactions between the catalyst and the substrate.," ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 229, iss. Part 2, pp. 357-ORGN, 2005.
[Bibtex]
@article ISI:000235066601459,
Author = Malkov, AV and Bell, M and Castelluzo, F and Bendova, L and Hobza, P and
Kocovsky, P,
Title = Chiral pyridine N-oxides as novel organocatalysts for the asymmetric
allylation of aldehydes with allyltrichlorosilanes and the role of
arene-arene interactions between the catalyst and the substrate.,
Journal = ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2005,
Volume = 229,
Number = Part 2,
Pages = 357-ORGN,
Month = MAR 13,
Note = 229th National Meeting of the American-Chemical-Society, San Diego, CA,
MAR 13-17, 2005,
Organization = Amer Chem Soc,
ISSN = 0065-7727,
Unique-ID = ISI:000235066601459,
J. Vondrasek, L. Bendova, V. Klusak, and P. Hobza, "Unexpectedly strong energy stabilization inside the hydrophobic core of
small protein rubredoxin mediated by aromatic residues: Correlated ab
initio quantum chemical calculations," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 127, iss. 8, pp. 2615-2619, 2005.
[Bibtex]
@article ISI:000227308100046,
Author = Vondrasek, J and Bendova, L and Klusak, V and Hobza, P,
Title = Unexpectedly strong energy stabilization inside the hydrophobic core of
small protein rubredoxin mediated by aromatic residues: Correlated ab
initio quantum chemical calculations,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2005,
Volume = 127,
Number = 8,
Pages = 2615-2619,
Month = MAR 2,
Abstract = The formation of a hydrophobic core of globular proteins is believed to
be the consequence of exterior hydrophobic forces of entropic nature.
This, together with the low occurrence of hydrogen bonds in the protein
core, leads to the opinion that the energy contribution of core
formation to protein folding and stability is negligible. We show that
stabilization inside the hydrophobic core of a small protein,
rubredoxin, determined by means of high-level correlated ab initio
calculations (complete basis set limit of MP2 stabilization energy +
CCSD(T) correction term), amounted to similar to50 kcal/mol. These
results clearly demonstrate strong attraction inside a hydrophobic core.
This finding may lead to substantial changes in the current view of
protein folding. We also point out the inability of the DFT/B3LYP method
to describe a strong attraction between studied amino acids.,
DOI = 10.1021/ja044607h,
ISSN = 0002-7863,
Unique-ID = ISI:000227308100046,
I. Dabkowska, H. Gonzalez, P. Jurecka, and P. Hobza, "Stabilization energies of the hydrogen-bonded and stacked structures of
nucleic acid base pairs in the crystal geometries of CG, AT, and AC DNA
steps and in the NMR geometry of the 5 `-d(GCGAAGC)-3 ` hairpin:
Complete basis set calculations at the MP2 and CCSD(T) levels," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 109, iss. 6, pp. 1131-1136, 2005.
[Bibtex]
@article ISI:000226955800024,
Author = Dabkowska, I and Gonzalez, HV and Jurecka, P and Hobza, P,
Title = Stabilization energies of the hydrogen-bonded and stacked structures of
nucleic acid base pairs in the crystal geometries of CG, AT, and AC DNA
steps and in the NMR geometry of the 5 `-d(GCGAAGC)-3 ` hairpin:
Complete basis set calculations at the MP2 and CCSD(T) levels,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2005,
Volume = 109,
Number = 6,
Pages = 1131-1136,
Month = FEB 17,
Abstract = Stabilization energies of the H-bonded and stacked structures of a DNA
base pair were studied in the crystal structures of adenine-thymine,
cytosine-guanine, and adenine-cytosine steps as well as in the
5'-d(GCGAAGC)-3' hairpin (utilizing the NMR geometry). Stabilization
energies were determined as the sum of the complete basis set (CBS)
limit of MP2 stabilization energies and the DeltaE(CCSD(T)) -
DeltaE(MP2) correction term evaluated with the 6-31G*(0.25) basis set.
The CBS limit was determined by a two-point extrapolation using the
aug-cc-pVXZ basis sets for X = D and T. While the H-bonding energies are
comparable to those of base pairs in a crystal and a vacuum, the
stacking energies are considerably smaller in a crystal. Despite this,
the stacking is still important and accounts for a significant part of
the overall stabilization. It contributes equally to the stability of
DNA as does H-bonding for AT-rich DNAs, while in the case of GC-rich
DNAs it forms about one-third of the total stabilization. Interstrand
stacking reaches surprisingly large values, well comparable to the
intrastrand ones, and thus contributes significantly to the overall
stabilization. The hairpin structure is characterized by significant
stacking, and both guanine(...)cytosine pairs possess stacking energies
larger than 11.5 kcal/mol. A high portion of stabilization in the
studied hairpin comes from stacking (similar to that found for AT-rich
DNAs) despite the fact that it contains two GC Watson-Crick pairs having
very large H-bonding stabilization. The DFT/B3LYP/6-31G** method
yields satisfactory values of interaction energies for H-bonded
structures, while it fails completely for stacking.,
DOI = 10.1021/jp046738a,
ISSN = 1089-5639,
Unique-ID = ISI:000226955800024,
M. Hanus, M. Kabelac, D. Nachtigallova, and P. Hobza, "Mutagenic properties of 5-halogenuracils: Correlated quantum chemical ab
initio study," BIOCHEMISTRY, vol. 44, iss. 5, pp. 1701-1707, 2005.
[Bibtex]
@article ISI:000226802000033,
Author = Hanus, M and Kabelac, M and Nachtigallova, D and Hobza, P,
Title = Mutagenic properties of 5-halogenuracils: Correlated quantum chemical ab
initio study,
Journal = BIOCHEMISTRY,
Year = 2005,
Volume = 44,
Number = 5,
Pages = 1701-1707,
Month = FEB 8,
Abstract = The relative stability of all possible 5-bromouracil tautomers was
studied theoretically in a gas phase, in a microhydrated environment
(with one water molecule), and in bulk water. Tautomer structures were
determined by gradient optimization at the correlated ab initio quantum
chemical level with an extended basis set of atomic orbitals. The role
of water was examined by using a self-consistent reaction field method.
The relative stabilization and free energies in the gas phase, the
microhydrated environment, and the bulk water clearly support the
preference of the canonical keto form of 5-bromouracil in all mentioned
environments. An increased abundance of enol tautomers when passing from
uracil to 5-bromouracil is not supported by our calculations. Thus, the
tautomeric model of the mutagenic activity of 5-bromouracil proposed
previously [Hu et al. Biochemistry (2004) 43, 636 1] can be refuted.
The validity of other mutagenic models was also discussed, and finally a
new mechanism for explaining the mutagenic activity of halogenuracils
based on their different behaviors in triplet excited states was
suggested.,
DOI = 10.1021/bi048112g,
ISSN = 0006-2960,
Unique-ID = ISI:000226802000033,
A. Abo-Riziq, L. Grace, E. Nir, M. Kabelac, P. Hobza, and M. de Vries, "Photochemical selectivity in guanine-cytosine base-pair structures," PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF
AMERICA, vol. 102, iss. 1, pp. 20-23, 2005.
[Bibtex]
@article ISI:000226216400005,
Author = Abo-Riziq, A and Grace, L and Nir, E and Kabelac, M and Hobza, P and de
Vries, MS,
Title = Photochemical selectivity in guanine-cytosine base-pair structures,
Journal = PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF
AMERICA,
Year = 2005,
Volume = 102,
Number = 1,
Pages = 20-23,
Month = JAN 4,
Abstract = Prebiotic chemistry presumably took place before formation of an
oxygen-rich atmosphere and thus under conditions of intense short
wavelength UV irradiation. Therefore, the UV photochemical stability of
the molecular building blocks of life may have been an important
selective factor in determining the eventual chemical makeup of critical
biomolecules. To investigate the role of UV irradiation in base-pairing
we have studied guanine (G) and cytosine (C) base pairs in the absence
of the RNA backbone. We distinguished base-pair structures by IR-UV
hole-burning spectroscopy as well as by high-level correlated ab initio
calculations. The Watson-Crick structure exhibits broad UV absorption,
in stark contrast to other GC structures and other base-pair structures.
This broad absorption may be explained by a rapid internal conversion
that makes this specific base pair arrangement uniquely photochemically
stable.,
DOI = 10.1073/pnas.0408574102,
ISSN = 0027-8424,
Unique-ID = ISI:000226216400005,
J. Cerny and P. Hobza, "The X3LYP extended density functional accurately describes H-bonding but
fails completely for stacking," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 7, iss. 8, pp. 1624-1626, 2005.
[Bibtex]
@article ISI:000228241500003,
Author = Cerny, J and Hobza, P,
Title = The X3LYP extended density functional accurately describes H-bonding but
fails completely for stacking,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2005,
Volume = 7,
Number = 8,
Pages = 1624-1626,
Abstract = The performance of the recently introduced X3LYP density functional
which was claimed to significantly improve the accuracy for H-bonded and
van der Waals complexes was tested for extended H-bonded and stacked
complexes (nucleic acid base pairs and amino acid pairs). In the case of
planar H-bonded complexes (guanine ... cytosine, adenine ... thymine)
the DFT results nicely agree with accurate correlated ab initio results.
For the stacked pairs (uracil dimer, cytosine dimer, adenine ... thymine
and guanine ... cytosine) the DFT fails completely and it was even not
able to localize any minimum at the stacked subspace of the potential
energy surface. The geometry optimization of all these stacked clusters
leads systematically to the planar H-bonded pairs. The amino acid pairs
were investigated in the crystal geometry. DFT again strongly
underestimates the accurate correlated ab initio stabilization energies
and usually it was not able to describe the stabilization of a pair. The
X3LYP functional thus behaves similarly to other current functionals.
Stacking of nucleic acid bases as well as interaction of amino acids was
described satisfactorily by using the tight-binding DFT method, which
explicitly covers the London dispersion energy.,
DOI = 10.1039/b502769c,
ISSN = 1463-9076,
Unique-ID = ISI:000228241500003,
J. Rejnek, M. Hanus, M. Labelac, F. Ryjacek, and P. Hobza, "Correlated ab initio study of nucleic acid bases and their tautomers in
the gas phase, in a microhydrated environment and in aqueous solution.
Part 4. Uracil and thymine," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 7, iss. 9, pp. 2006-2017, 2005.
[Bibtex]
@article ISI:000228634500018,
Author = Rejnek, J and Hanus, M and Labelac, M and Ryjacek, F and Hobza, P,
Title = Correlated ab initio study of nucleic acid bases and their tautomers in
the gas phase, in a microhydrated environment and in aqueous solution.
Part 4. Uracil and thymine,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2005,
Volume = 7,
Number = 9,
Pages = 2006-2017,
Abstract = Altogether 13 keto and enol tautomers of uracil and 13 keto and enol
tautomers of thymine were studied theoretically in the gas phase, in a
microhydrated environment ( 1 and 2 water molecules) and in a water
environment. Bulk water was described using the thermodynamic
integration method, Conductor-like polarizable continuum model (C-PCM,
COSMO) and hybrid model (C-PCM + 1-2 explicit water molecules). The
structures of various tautomers were determined at the RI-MP2 level
using the TZVPP basis set while relative energies were determined at the
CCSD(T) level. The relative free energies at 298 K were based on the
relative energies mentioned above and zero-point vibration energies, and
temperature dependent enthalpy terms and entropies evaluated at the
MP2/6-31G** level. The effect of bulk solvent on the relative
stability of uracil and thymine tautomers was studied using molecular
dynamics free energy calculations by means of the thermodynamic
integration method and self-consistent reaction field. Despite the
completely different nature of these methods they provide comparable
solvation free energies. Besides theoretical investigation, experimental
detection of uracil and thymine tautomers was performed by means of
steady-state fluorescence. We conclude that it is impossible to utilize
the method used by Suwaiyan and Morsy (M. A. Morsy, A. M. Al-Somali and
A. Suwaiyan, J. Phys. Chem. B, 1999, 103( 50), 11205) for tautomer
detection, even if a very sensitive fluorimeter is used. Theoretical
relative energies and free energies for isolated uracil and thymine
tautomers support the existence of the canonical form only. The
microhydrated environment and bulk solvent stabilize enol forms more
than the canonical keto one, but gas phase destabilization of these enol
forms is too high. Population of rare enol forms of uracil and thymine
in bulk water will thus be very low and canonical structure will also be
dominant in this phase.,
DOI = 10.1039/b501499a,
ISSN = 1463-9076,
Unique-ID = ISI:000228634500018,
B. Crews, A. Abo-Riziq, L. Grace, M. Callahan, M. Kabelac, P. Hobza, and M. de Vries, "IR-UV double resonance spectroscopy of guanine-H2O clusters," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 7, iss. 16, pp. 3015-3020, 2005.
[Bibtex]
@article ISI:000230931200004,
Author = Crews, B and Abo-Riziq, A and Grace, L and Callahan, M and Kabelac, M
and Hobza, P and de Vries, MS,
Title = IR-UV double resonance spectroscopy of guanine-H2O clusters,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2005,
Volume = 7,
Number = 16,
Pages = 3015-3020,
Abstract = We present the IR-UV double resonance spectrum of guanine monohydrate in
the region 3100 cm(-1) to 3800 cm(-1) along with the energies and
frequencies of these structures calculated at the non-empirical
correlated ab initio RI-MP2/cc-pVDZ level. We assign the structures of
guanine-water clusters by comparing the experimental spectra with the ab
initio calculations and with the IR spectra of the bare guanine monomer.
We find two clusters with guanine in the enol-amino tautomeric form and
one structure with guanine in the keto-amino form.,
DOI = 10.1039/b506107e,
ISSN = 1463-9076,
Unique-ID = ISI:000230931200004,
J. Fanfrlik, J. Rejnek, M. Hanus, and P. Hobza, "Hydration Gibbs energies of nucleic acid bases determined by Gibbs
energy perturbation, continuous and hybrid approaches," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 70, iss. 11, pp. 1756-1768, 2005.
[Bibtex]
@article ISI:000234236700002,
Author = Fanfrlik, J and Rejnek, J and Hanus, M and Hobza, P,
Title = Hydration Gibbs energies of nucleic acid bases determined by Gibbs
energy perturbation, continuous and hybrid approaches,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2005,
Volume = 70,
Number = 11,
Pages = 1756-1768,
Abstract = The hydration Gibbs energies of adenine, cytosine, guanine, thymine,
uracil and isoguanine are determined by the molecular
dynamics-thermodynamic integration method (MD-TI) and using continuous
COSMO and hybrid models. The role of solvents in the COSMO model is
described by permittivity and by combining the permittivity and specific
hydration of single water molecules placed on the energetically most
probable position in the hybrid model. The hybrid model describes
hydration similarly to the COSMO model; both the continuous methods are
in good agreement with the MD-TI method. Differences are small and the
use of both models can be recommended.,
DOI = 10.1135/cccc20051756,
ISSN = 0010-0765,
Unique-ID = ISI:000234236700002,
[Bibtex]
@article ISI:000235422000004,
Author = Hobza, P,
Title = Did Parmenides hold that thinking and being are identical?,
Journal = FILOSOFICKY CASOPIS,
Year = 2005,
Volume = 53,
Number = 5,
Pages = 703-716,
Abstract = It is usually assumed that Parmenides somehow identified thinking with
being (entity), and the thesis of the identity of thinking and being is
meant to be present in two verses (B 8.34 and B 3). Nevertheless, on a
thorough analysis of both verses it is evident that the thesis of the
identity of thinking and being cannot be attributed to Parmenides. The
main interpretational problem of verse B 8.34 is tauton (same,
identical), which is usually understood as a predicate; on this
understanding then the verse expresses the identity between thinking and
being. However, from the context (i.e. from the verse B 8.29) it follows
that tauton is rather the subject and is intended as a synonym with eon
(entity), which excludes the whole verse treating of the identity
between thinking and being. Fragment B 3, the interpretation of which is
essentially ambivalent, is evidentally a later paraphrase and not the
authentic verse.,
ISSN = 0015-1831,
Unique-ID = ISI:000235422000004,
2004
J. Langmaier, Z. Samec, E. Samcova, P. Hobza, and D. Reha, "Origin of difference between one-electron redox potentials of guanosine
and guanine: Electrochemical and quantum chemical study," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 108, iss. 40, pp. 15896-15899, 2004.
[Bibtex]
@article ISI:000224213500062,
Author = Langmaier, J and Samec, Z and Samcova, E and Hobza, P and Reha, D,
Title = Origin of difference between one-electron redox potentials of guanosine
and guanine: Electrochemical and quantum chemical study,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2004,
Volume = 108,
Number = 40,
Pages = 15896-15899,
Month = OCT 7,
Abstract = Cyclic voltammetry was used to measure the rates of the chemical
oxidation of guanine (G), guanosine (Gs), 2'-deoxyguanosine (dG), and
2'-deoxyguanosine Y-monophosphate (dGMP) by electrochemically generated
tris(2,2'-bipyridyl)ruthenium(III). The numeric fit of voltammograms to
an ECCCE type of mechanism provided the equilibrium and rate constants
of the two-step chemical oxidation of the guanine species. One-electron
redox potentials evaluated from the equilibrium constant of the first
electron uptake follow the sequence G < Gs approximate to dG approximate
to dGMP, indicating that guanine is oxidized most easily. This sequence
is expressed in the rate constant, which apparently follows the expected
driving force dependence. Ab initio molecular orbital calculations were
carried out using the DFT/B3LYP method with 6-31G** and
6-31++G** basis sets, and also the RI-MP2 method with the cc-pVDZ
basis set, so as to clarify the role of various factors contributing to
the redox potential. Theoretical results suggest that the difference
between the one-electron redox potentials of Gs and G (ca. 0.13 V)
originates partly from the higher energy of proton dissociation from the
cation radical Gs(.+) and partly from the higher difference in the
hydration energy between the deprotonated radical Gs(-H)(.) and the
parent Gs, which compensate for the lower ionization potential of Gs
compared to that of G.,
DOI = 10.1021/jp0481207,
ISSN = 1520-6106,
Unique-ID = ISI:000224213500062,
J. Sponer, P. Jurecka, and P. Hobza, "Accurate interaction energies of hydrogen-bonded nucleic acid base pairs," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 126, iss. 32, pp. 10142-10151, 2004.
[Bibtex]
@article ISI:000223279300057,
Author = Sponer, J and Jurecka, P and Hobza, P,
Title = Accurate interaction energies of hydrogen-bonded nucleic acid base pairs,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2004,
Volume = 126,
Number = 32,
Pages = 10142-10151,
Month = AUG 18,
Abstract = Hydrogen-bonded nucleic acids base pairs substantially contribute to the
structure and stability of nucleic acids. The study presents reference
ab initio structures and interaction energies of selected base pairs
with binding energies ranging from -5 to -47 kcal/mol. The molecular
structures are obtained using the RI-MP2 (resolution of identity MP2)
method with extended cc-pVTZ basis set of atomic orbitals. The RI-MP2
method provides results essentially identical with the standard MP2
method. The interaction energies are calculated using the Complete Basis
Set (CBS) extrapolation at the RI-MP2 level. For some base pairs,
Coupled-Cluster corrections with inclusion of noniterative triple
contributions (CCSD(T)) are given. The calculations are compared with
selected medium quality methods. The PW91 DFT functional with the
6-31G(**) basis set matches well the RI-MP2/CBS absolute interaction
energies and reproduces the relative values of base pairing energies
with a maximum relative error of 2.6 kcal/mol when applied with
Becke3LYP-optimized geometries. The Becke3LYP DFT functional
underestimates the interaction energies by few kcal/mol with relative
error of 2.2 kcal/mol. Very good performance of nonpolarizable Cornell
et al. force field is confirmed and this indirectly supports the view
that H-bonded base pairs are primarily stabilized by electrostatic
interactions.,
DOI = 10.1021/ja048436s,
ISSN = 0002-7863,
Unique-ID = ISI:000223279300057,
F. Madeja, M. Havenith, K. Nauta, R. Miller, J. Chocholousova, and P. Hobza, "Polar isomer of formic acid dimers formed in helium nanodroplets," JOURNAL OF CHEMICAL PHYSICS, vol. 120, iss. 22, pp. 10554-10560, 2004.
[Bibtex]
@article ISI:000221538200022,
Author = Madeja, F and Havenith, M and Nauta, K and Miller, RE and Chocholousova,
J and Hobza, P,
Title = Polar isomer of formic acid dimers formed in helium nanodroplets,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 2004,
Volume = 120,
Number = 22,
Pages = 10554-10560,
Month = JUN 8,
Abstract = The infrared spectrum of formic acid dimers in helium nanodroplets has
been observed corresponding to excitation of the ``free'' OH and CH
stretches. The experimental results are consistent with a polar acyclic
structure for the dimer. The formation of this structure in helium, as
opposed to the much more stable cyclic isomer with two O-H.O hydrogen
bonds, is attributed to the unique growth conditions that exist in
helium droplets, at a temperature of 0.37 K. Theoretical calculations
are also reported to aid in the interpretation of the experimental
results. At long range the intermolecular interaction between the two
monomers is dominated by the dipole-dipole interaction, which favors the
formation of a polar dimer. By following the minimum-energy path, the
calculations predict the formation of an acyclic dimer having one O-H.O
and one C-H.O contact. This structure corresponds to a local minimum on
the potential energy surface and differs significantly from the
structure observed in the gas phase. (C) 2004 American Institute of
Physics.,
DOI = 10.1063/1.1709942,
ISSN = 0021-9606,
Unique-ID = ISI:000221538200022,
J. Pittner and P. Hobza, "CCSDT and CCSD(T) calculations on model H-bonded and stacked complexes," CHEMICAL PHYSICS LETTERS, vol. 390, iss. 4-6, pp. 496-499, 2004.
[Bibtex]
@article ISI:000221730600035,
Author = Pittner, J and Hobza, P,
Title = CCSDT and CCSD(T) calculations on model H-bonded and stacked complexes,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 2004,
Volume = 390,
Number = 4-6,
Pages = 496-499,
Month = JUN 1,
Abstract = The CCSD(T) and CCSDT interaction energies were determined for model
planar H-bonded complexes (formamide... form-formamide, formamidine...
formamidine) and stacked complexes (ethylene... ethylene,
formaldehyde... formaldehyde). Various basis sets from the
6-31G*(0.25) to aug-cc-pVDZ were used. Difference between CCSD(T) and
CCSDT interaction energies were small and become negligible (bellow 0.1
kcal/mol) if the aug-cc-pVDZ (or aug-cc-pVDZ/cc-pVDZ) basis set was
applied. This result strongly supports the use of the CCSD(T) method for
determination of true stabilization energies of extended complexes. (C)
2004 Published by Elsevier B.V.,
DOI = 10.1016/j.cplett.2004.04.009,
ISSN = 0009-2614,
Unique-ID = ISI:000221730600035,
J. Sponer, V. Sychrovsky, P. Hobza, and J. Sponer, "Interactions of hydrated divalent metal cations with nucleic acid bases.
How to relate the gas phase data to solution situation and binding
selectivity in nucleic acids," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 6, iss. 10, pp. 2772-2780, 2004.
[Bibtex]
@article ISI:000222182100030,
Author = Sponer, JE and Sychrovsky, V and Hobza, P and Sponer, J,
Title = Interactions of hydrated divalent metal cations with nucleic acid bases.
How to relate the gas phase data to solution situation and binding
selectivity in nucleic acids,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2004,
Volume = 6,
Number = 10,
Pages = 2772-2780,
Month = MAY 21,
Abstract = Binding modes of hydrated Zn2+ and Mg2+ cations to the N7 and O6
positions of guanine have been characterized by state-of-the-art ab
initio model calculations. We show how differences in the electronic
structure of the cationic complexes, as revealed by gas-phase
computations, translate into differences in the biological function of
the two studied metals. The thermodynamic driving force of the metal
binding process is estimated on the basis of interaction energies and
total electronic energies. The computed results unambiguously reveal
that the N7 position of guanine exhibits a greater propensity to bind
Zn2+ than Mg2+ while both cations have a similar affinity to bind to O6.
Contrary to the intuitive expectations, however, the computed data do
not suggest any superiority of the N7 inner shell binding mode for Zn2+
compared to the O6 binding. For Mg2+ the O6 inner shell binding mode is
favored over the N7 one. The gas-phase data, when properly exrapolated,
provide a relevant picture of many (though not all) fundamental aspects
of the diversity of cation binding to nucleic acids.,
DOI = 10.1039/b404306p,
ISSN = 1463-9076,
Unique-ID = ISI:000222182100030,
M. Kabelac, C. Plutzer, K. Kleinermanns, and P. Hobza, "Isomer selective IR experiments and correlated ab initio quantum
chemical calculations support planar H-bonded structure of the 7-methyl
adenine center dot center dot center dot adenine and stacked structure
of the 9-methyl adenine center dot center dot center dot adenine base
pairs," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 6, iss. 10, pp. 2781-2785, 2004.
[Bibtex]
@article ISI:000222182100031,
Author = Kabelac, M and Plutzer, C and Kleinermanns, K and Hobza, P,
Title = Isomer selective IR experiments and correlated ab initio quantum
chemical calculations support planar H-bonded structure of the 7-methyl
adenine center dot center dot center dot adenine and stacked structure
of the 9-methyl adenine center dot center dot center dot adenine base
pairs,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2004,
Volume = 6,
Number = 10,
Pages = 2781-2785,
Month = MAY 21,
Abstract = In this paper we show that the stacked structures of 9-methyl adenine...
adenine are comparably stable as the most stable hydrogen bonded
structures and that the calculated IR pattern of the stacked structures
is in a very good agreement with the experimental spectrum. The pair
7-methyl adenine... adenine on the other hand shows a nearly planar
hydrogen bond arrangement and no stacked structure was observed.,
DOI = 10.1039/b316433k,
ISSN = 1463-9076,
Unique-ID = ISI:000222182100031,
J. Bakker, I. Compagnon, G. Meijer, G. von Helden, M. Kabelac, P. Hobza, and M. de Vries, "The mid-IR absorption spectrum of gas-phase clusters of the nucleobases
guanine and cytosine," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 6, iss. 10, pp. 2810-2815, 2004.
[Bibtex]
@article ISI:000222182100036,
Author = Bakker, JM and Compagnon, I and Meijer, G and von Helden, G and Kabelac,
M and Hobza, P and de Vries, MS,
Title = The mid-IR absorption spectrum of gas-phase clusters of the nucleobases
guanine and cytosine,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2004,
Volume = 6,
Number = 10,
Pages = 2810-2815,
Month = MAY 21,
Abstract = The mid-infrared (IR) absorption spectrum of jet-cooled clusters of the
nucleobases guanine and cytosine has been recorded in the 500-1800
cm(-1) range by ion-dip spectroscopy. Some 30 clearly separated and
sharp resonances are observed. The combination of the experimental data
with new high-level ab initio calculations is consistent with a previous
structural assignment and a tentative assignment is made to the K7-1E
structure of guanine-cytosine. These data can serve as a test of the
method in the mid-IR regime.,
DOI = 10.1039/b316158g,
ISSN = 1463-9076,
Unique-ID = ISI:000222182100036,
W. Pohle, D. Gauger, M. Bohl, E. Mrazkova, and P. Hobza, "Lipid hydration: Headgroup CH moieties are involved in water binding," BIOPOLYMERS, vol. 74, iss. 1-2, pp. 27-31, 2004.
[Bibtex]
@article ISI:000221160600004,
Author = Pohle, W and Gauger, DR and Bohl, M and Mrazkova, E and Hobza, P,
Title = Lipid hydration: Headgroup CH moieties are involved in water binding,
Journal = BIOPOLYMERS,
Year = 2004,
Volume = 74,
Number = 1-2,
Pages = 27-31,
Month = MAY-JUN,
Note = 10th European Conference on the Spectroscopy of Biological Molecules
(ECSBM 2003), Szeged, HUNGARY, AUG 30-SEP 04, 2003,
Abstract = To explore the interaction potential of phospholipids, we have studied
the hydration of diacyl phosphatidylcholine (PC) and
methylphosphocholine (MePC), a pertinent model compound, by ir
spectroscopy. Related ab initio Hartree-Fock calculations were performed
for MePC Water is considered ideal as a relevant probe molecule.
Spectroscopic data for MePC reveal a strong influence of bound hydration
water not only on the phosphate groups but also onto the putatively
apolar CHn groups. The same could be demonstrated for deuterated
dimyristoyl PC taken as a ``complete'' lipid molecule: both headgroup
methyl and methylene moieties art gradually, but remarkably affected by
hydration, as evidenced by strong wavenumber upshifts of C-H stretching
vibration hands. These findings may originate in directed interactions
of the CHn groups with bound water molecules, but hydration-driven
conformational changes of PC headgroups could also occur. The results of
the ab initio calculations rationalize the first explanation by
predicting a substantial contribution of specific C-(HOH2)-O-...
interactions, mainly characterized by a dramatic loss of electron
density of the sigma* antibonding molecular orbitals of C-H bonds.
Hence, the propensity of the lipid headgroup methyl and methylene groups
to act as donor sites in hydrogen bonding must no longer be ignored when
considering the interaction potential of PCs. (C) 2004 Wiley
Periodicals, Inc.,
DOI = 10.1002/bip.20037,
ISSN = 0006-3525,
Unique-ID = ISI:000221160600004,
P. Jurecka, J. Sponer, and P. Hobza, "Potential energy surface of the cytosine dimer: MP2 complete basis set
limit interaction energies, CCSD(T) correction term, and comparison with
the AMBER force field," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 108, iss. 17, pp. 5466-5471, 2004.
[Bibtex]
@article ISI:000220997300048,
Author = Jurecka, P and Sponer, J and Hobza, P,
Title = Potential energy surface of the cytosine dimer: MP2 complete basis set
limit interaction energies, CCSD(T) correction term, and comparison with
the AMBER force field,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2004,
Volume = 108,
Number = 17,
Pages = 5466-5471,
Month = APR 29,
Abstract = The complete basis set (CBS) limit of the MP2 interaction energy and the
CCSD(T) correction term determined as the difference between the CCSD(T)
and MP2 interaction energies were evaluated for 17 stacked and 4
H-bonded structures of the cytosine dimer. Extrapolation to the MP2 CBS
limit was done using the aug-cc-pVDZ and aug-cc-pVTZ results, and the
CCSD(T) correction term was determined with the 6-31G*(0.25) basis
set. Extrapolation to the CBS limit is essential in all parts of the
potential energy surface and affects mainly the absolute MP2
stabilization energy. The effect on the relative stability is smaller
but not negligible. The CCSD(T) correction term is for stacked
structures with large overlaps of the monomers substantially repulsive
but not uniform. Thus, when comparing the final estimate (abbreviated as
CBS(T)) with previously used medium-level MP2/6-31G*(0.25) data, the
CCSD(T) correction partially compensates for the enhanced absolute MP2
CBS stabilization but. further increases the relative differences
between different structures. The difference between the
MP2/6-31G*(0.25) and the new CBS(T) reference values is in the range
of +0.3 to -2.1 kcal/mol. The difference between the parallel and
antiparallel structures is enhanced by 2 kcal/mol. The CCSD(T)
correction is negligible in the H-bonded structure and in stacked
structures with a minimal overlap of bases. The new reference CBS(T)
data are compared with the AMBER force field testing both HF and MP2
electrostatic potential fitted atom-centered charges. The overall
agreement of the force field with the CBS(T) data is very satisfactory.
We nevertheless identify differences that are attributed to polarization
and short-term effects not included in the force field. Interestingly,
whereas MP2/6-31G*(0.25) calculations are better reproduced with the
MP2 variant of the force field the new CBS(T) reference data are in
better agreement with the use of HF charges in the force field,
indicating the enhanced role of polarization.,
DOI = 10.1021/jp049956c,
ISSN = 1520-6106,
Unique-ID = ISI:000220997300048,
M. Hocek, P. Stepnicka, J. Ludvik, I. Cisarova, I. Votruba, D. Reha, and P. Hobza, "Ferrocene-modified purines as potential electrochemical markers:
Synthesis, crystal structures, electrochemistry and cytostatic activity
of (ferrocenylethynyl)- and (ferrocenylethyl)purines," CHEMISTRY-A EUROPEAN JOURNAL, vol. 10, iss. 8, pp. 2058-2066, 2004.
[Bibtex]
@article ISI:000221025200022,
Author = Hocek, M and Stepnicka, P and Ludvik, J and Cisarova, I and Votruba, I
and Reha, D and Hobza, P,
Title = Ferrocene-modified purines as potential electrochemical markers:
Synthesis, crystal structures, electrochemistry and cytostatic activity
of (ferrocenylethynyl)- and (ferrocenylethyl)purines,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2004,
Volume = 10,
Number = 8,
Pages = 2058-2066,
Month = APR 19,
Abstract = Palladium-catalyzed Sonoga-shira cross-coupling reactions of halopurines
9-benzyl-6-chloropurine (2a), 9-benzyl-8-bromoadenine (2b), and
9-benzyl-2-chloroadenine (2c) with ethynylferrocene (1) gave the
corresponding (ferrocenylethynyl)purines 3a-c in moderate to good
yields. Catalytic hydrogenation of these alkynes over Pd/C afforded the
respective saturated [2(ferrocenyl)ethyl]purines 4 a-c. The crystal
structures 3a, 3b, 4a and 4b as determined by X-ray diffraction show
interesting solid-state interactions, markedly different for purines 3a
and 4a on one hand and adenines 3b and 4b that possess a free amino
group on the other. Electrochemistry of electrochemically labelled
purines 3 and 4 has been studied by voltammetry and cyclic voltammetry
on platinum disc electrode and the experimental oxidation potentials
were confirmed and explained by ionization potentials from theoretical
DFT calculations. Several compounds of this series exhibited a
considerable cytostatic effect.,
DOI = 10.1002/chem.200305621,
ISSN = 0947-6539,
Unique-ID = ISI:000221025200022,
W. Zierkiewicz, D. Michalska, and P. Hobza, "The barrier to internal rotation and electronic effects in
para-halogenophenols: theoretical study," CHEMICAL PHYSICS LETTERS, vol. 386, iss. 1-3, pp. 95-100, 2004.
[Bibtex]
@article ISI:000189244300016,
Author = Zierkiewicz, W and Michalska, D and Hobza, P,
Title = The barrier to internal rotation and electronic effects in
para-halogenophenols: theoretical study,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 2004,
Volume = 386,
Number = 1-3,
Pages = 95-100,
Month = MAR 1,
Abstract = The OH rotational barrier height in phenol and para-halogenophenols
systematically decreases in the series Br, Cl and F, while the changes
in the CO bond length and CO bond strength do not follow this order. On
the basis of the NBO analysis it is suggested that lowering of the
barrier height in p-halogenophenols is caused by the decrease of
electron density in the sigma antibonding orbital, sigma*(CO), and a
weak occupancy of this orbital is due to the electron delocalization
from the sigma(CC) ring orbitals. This effect can be either reinforced
or reduced, depending on the extent of conjugation between the p(z)-type
lone electron pair on the oxygen atom and the pi*(CC) acceptor
orbitals in the aromatic ring. (C) 2004 Elsevier B.V. All rights
reserved.,
DOI = 10.1016/j.cplett.2004.01.026,
ISSN = 0009-2614,
Unique-ID = ISI:000189244300016,
M. Hanus, M. Kabelac, J. Rejnek, F. Ryjacek, and P. Hobza, "Correlated ab initio study of nucleic acid bases and their tautomers in
the gas phase, in a microhydrated environment, and in aqueous solution.
Part 3. Adenine," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 108, iss. 6, pp. 2087-2097, 2004.
[Bibtex]
@article ISI:000188831700038,
Author = Hanus, M and Kabelac, M and Rejnek, J and Ryjacek, F and Hobza, P,
Title = Correlated ab initio study of nucleic acid bases and their tautomers in
the gas phase, in a microhydrated environment, and in aqueous solution.
Part 3. Adenine,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2004,
Volume = 108,
Number = 6,
Pages = 2087-2097,
Month = FEB 12,
Abstract = Altogether, 14 amino and imino tautomers of adenine were studied
theoretically in the gas phase, in a microhydrated environment (one and
two water molecules), and in bulk water environment using the
thermodynamic integration method (MD-TI), conductor-like polarizable
continuum model (C-PCM, COSMO), and a hybrid model (C-PCM + one to three
explicit water molecules). The structures and relative energies of
various tautomers were determined at the RI-MP2 level using the TZVPP
basis set. The relative enthalpies at 0 K and relative free energies at
298 K were based on relative energies and zero-point vibration energies,
temperature-dependent enthalpy terms, and entropies evaluated at the
MP2/6-31G** level. The effect of bulk solvent on the relative
stability of adenine tautomers was studied by molecular dynamics free
energy calculations using the thermodynamic integration method and
self-consistent reaction field. The dipole moment of the canonical form
is rather small (2.8 D) but three rare imino tautomers have very large
dipole moments (more than 10 D). The canonical form is the global
minimum at all theoretical levels in the gas phase, in a microhydrated
environment, and in the bulk water. Two unusual rare amino tautomers
having hydrogens at N3 and N7, respectively, are less stable in the gas
phase by more than 7 kcal/mol and represent the first and the second
local rninimum. Microhydration, as well as bulk water, stabilizes these
unusual tautomers, and the energy gap between them and the canonical
form is reduced, but the canonical tautomer remains the global minimum
in all three phases. Relative free energies (T = 298 K) of these two
unusual tautomers in the bulk water evaluated by molecular dynamics free
energy calculations are 2.5 and 2.8 kcal/mol, which supports their
coexistence in this phase. The C-PCM results agree well with the MD-Tl
data, and the agreement became close when considering not only the bare
tautomers but their complexes with several water molecules representing
first solvation shell. Other tautomers are considerably less stable (by
12-45 kcal/mol), and neither a microhydrated environment nor bulk water
can change this unfavorable tautomeric equilibrium. The theoretical data
predicting the coexistence of the canonical form and the N3 and the N7
tautomers in bulk water nicely agreed with experimental data obtained
from NMR measurements of the adenine tautomers in DMSO (Laxer, A.;
Major, D. T.; Gottlieb, H. E.; Fischer, B. J. Org. Client. 2001, 66,
5463.).,
DOI = 10.1021/jp036090m,
ISSN = 1520-6106,
Unique-ID = ISI:000188831700038,
V. Sychrovsky, J. Sponer, and P. Hobza, "Theoretical calculation of the NMR spin-spin coupling constants and the
NMR shifts allow distinguishability between the specific direct and the
water-mediated binding of a divalent metal cation to guanine," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 126, iss. 2, pp. 663-672, 2004.
[Bibtex]
@article ISI:000188197800061,
Author = Sychrovsky, V and Sponer, J and Hobza, P,
Title = Theoretical calculation of the NMR spin-spin coupling constants and the
NMR shifts allow distinguishability between the specific direct and the
water-mediated binding of a divalent metal cation to guanine,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2004,
Volume = 126,
Number = 2,
Pages = 663-672,
Month = JAN 21,
Abstract = The calculated intermolecular and intramolecular indirect NMR spin-spin
coupling constants and NMR shifts were used for the discrimination
between the inner-shell and the outer-shell binding motif of hydrated
divalent cations Mg2+ or Zn2+ with a guanine base. The intermolecular
coupling constants (1)J(X, O6) and (1)J(X, N7) (X = Mg2+, Zn2+) can be
unambiguously assigned to the specific inner-shell binding motif of the
hydrated cation either with oxygen O6 or with nitrogen N7 of guanine.
The calculated coupling constants (1)J(Mg, O6) and (1)J(Zn, O6) were 6.2
and -17.5 Hz, respectively, for the inner-shell complex of cation
directly interacting with oxygen O6 of guanine. For the inner-shell
coordination of the cation at nitrogen N7 the calculated coupling
constants (1)J(Mg,N7) and (1)J(Zn,N7) were 5.6 and -36.5 Hz,
respectively. When the binding of the cation is water-mediated, the
coupling constant is zero. To obtain reliable shifts in NMR parameters,
hydrated guanine was utilized as the reference state. The calculated
change of NMR spin-spin coupling constants due to the hydration and
coordination of the cation with guanine is caused mainly by the
variation of Fermi-contact coupling contribution while the variation of
diamagnetic spin-orbit, paramagnetic spin-orbit, and spin-dipolar
coupling contributions is small. The change of s-character of guanine
sigma bonding, sigma antibonding, and lone pair orbitals upon the
hydration and cation coordination (calculated using the Natural Bond
Orbital analysis) correlates with the variation of the Fermi-contact
term. The calculated NMR shifts delta(N7) of -15.3 and -12.2 ppm upon
the coordination of Mg2+ and Zn2+ ion are similar to the NMR shift of
19.6 ppm toward the high field measured by Tanaka for N7 of guanine upon
the coordination of the Cd2+ cation (Tanaka, Y.; Kojima, C.; Morita, E.
H.; Kasai. Y.; Yamasaki, K.; Ono, A.; Kainosho, M.; Taira, K. J. Am.
Chem. Soc. 2002, 124, 4595-4601). The present data indicate that
measurements of NMR intermolecular coupling constants may be used to
discriminate between the specific inner- and outer-shell binding of
divalent cations to nucleobases in DNA and RNA.,
DOI = 10.1021/ja036942w,
ISSN = 0002-7863,
Unique-ID = ISI:000188197800061,
J. Chocholousova, V. Spirko, and P. Hobza, "First local minimum of the formic acid dimer exhibits simultaneously
red-shifted O-H center dot center dot center dot O and improper
blue-shifted C-H center dot center dot center dot O hydrogen bonds," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 6, iss. 1, pp. 37-41, 2004.
[Bibtex]
@article ISI:000187438000007,
Author = Chocholousova, J and Spirko, V and Hobza, P,
Title = First local minimum of the formic acid dimer exhibits simultaneously
red-shifted O-H center dot center dot center dot O and improper
blue-shifted C-H center dot center dot center dot O hydrogen bonds,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2004,
Volume = 6,
Number = 1,
Pages = 37-41,
Abstract = The first local minimum of the formic acid dimer exhibits simultaneously
red-shifted O-H...O and blue-shifted C-H...O hydrogen bonds. The
improper, blue-shifted hydrogen bond was investigated by means of the
NBO analysis, rehybridization model and optimization in the electric
field. It was shown that the electrostatic model cannot describe the
nature of the blue-shifted H-bond. From the NBO analysis it becomes
evident that the formation of the O-H...O hydrogen bond and C-H...O
improper hydrogen bond can be explained on the basis of an increase of
electron density in the sigma* antibonding O-H orbital and a decrease
of electron density in the sigma* antibonding C-H orbital. While the
former effect is easily explained on the basis of hyperconjugation, the
latter requires the existence of a new mesomeric structure characterized
by delocalization of electron density from the C-H sigma* antibonding
orbital to the remaining part of the complex. The rehybridization model
explains properly the formation of both hydrogen bonds but fails to
interpret the changes of the other bonds.,
DOI = 10.1039/b314148a,
ISSN = 1463-9076,
Unique-ID = ISI:000187438000007,
W. Zierkiewicz and P. Hobza, "The dihydrogen bond in X3C-H center dot center dot center dot H-M
complexes (X = F, Cl, Br; M = Li, Na, K). A correlated quantum chemical
ab initio and density functional theory study," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 6, iss. 23, pp. 5288-5296, 2004.
[Bibtex]
@article ISI:000225301400004,
Author = Zierkiewicz, W and Hobza, P,
Title = The dihydrogen bond in X3C-H center dot center dot center dot H-M
complexes (X = F, Cl, Br; M = Li, Na, K). A correlated quantum chemical
ab initio and density functional theory study,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2004,
Volume = 6,
Number = 23,
Pages = 5288-5296,
Abstract = Quantum chemical calculations were performed on nine dihydrogen-bonded
complexes with haloform (F3CH, Cl3CH and Br3CH) as a proton donor and
alkali metal hydride (HLi, HNa and HK) as a proton acceptor.
MP2/6-311++G(d, p) and B3LYP/6-311++G(d, p) results show that the
stabilization energies of these complexes are large and comparable to
the stabilization energies of standard H-bonded complexes. Elongation
and weakening ( red shift) of the CH, HNa and HK bonds upon complexation
were found while contraction and strengthening ( blue shift) was
observed in HLi. The H...H bond was found to be ionic and its ionicity
is larger than that of the H...Y bond in standard and improper H-bonds.
The calculated free energy (DG) revealed that only potassium hydride
complexes (F3CH...HK, Cl3CH...HK and Br3CH...HK) are stable under
standard conditions ( T = 298.150 K and p = 101.325 N m(-2)) in the gas
phase. To elucidate the role of the electrostatic contribution, the
optimization of the proton donor and proton acceptor molecules in the
electric field of a partner was performed. The HLi bond is contracted in
the electric field of the haloform while the HM ( M = Na, K) bonds are
elongated and the electrostatic field itself is sufficient explanation
of these phenomena. Natural bond order (NBO) and natural resonance
theory (NRT) analyses were performed. The NBO analysis revealed that
significant electron density was transferred from the sigma bonding
orbital of a proton acceptor to the antibonding sigma*(CH) orbital of
the proton donor. Symmetry adapted perturbation theory (SAPT) was
utilized to decompose the total interaction energy into physically
correct contributions.,
DOI = 10.1039/b410112j,
ISSN = 1463-9076,
Unique-ID = ISI:000225301400004,
[Bibtex]
@article ISI:000227714700001,
Author = Bohacek, K and Hobza, P,
Title = Ancient philosophy - Introduction,
Journal = FILOSOFICKY CASOPIS,
Year = 2004,
Volume = 52,
Number = 6,
Pages = 883-885,
ISSN = 0015-1831,
Unique-ID = ISI:000227714700001,
[Bibtex]
@article ISI:000227714700002,
Author = Hobza, P,
Title = Aristotle and Theophrastus as creators of Milesian philosophy,
Journal = FILOSOFICKY CASOPIS,
Year = 2004,
Volume = 52,
Number = 6,
Pages = 889-924,
Abstract = In my study I offer a new view of the thought of three Milesian
thinkers. A critical review of the sources shows that the Milesians did
not search for the arche (beginning, or origin) of the world. This
viewpoint is projected onto their thought on the basis of Aristotle's
interpretation which sees all predecessors through the prism of the
(more or less synonomous) concepts of principle (arche), cause (aition)
and element (stoicheion). An analysis of the sources shows that the
concept of arche as a philosophical concept has nothing in common with
Milesian speculation, but on the contrary enters philosophical
terminology from the mathematics of the fifth century, through Plato up
to Aristotle, where it is first understood as an ontological
constituent, or more precisely, principle, of the world. However, that
the Milesians did not search for the origin (arche) of the world throws
an entirely new light oil their thought. A critical analysis of, for
example, Anaximander's thought shows that the concept of the Unbounded
(to apeiron) which is traditionally understood as the basis of his
knowledge, is not his actual concept, but on the contrary Theophrastus'
interpretation. Again, Anaximenes cannot be placed under a ``theory of
physical changes'' based on gradual metamorphosis of the air as a
principle that enables the application of the Aristotelian categories of
dilution and compression. In summary: At the centre of Milesian
speculation was not a search for the origin (arche) of the world as
(Aristotelian) principles, but rather an engagement to outline the new
cosmogonical and cosmological picture of the world.,
ISSN = 0015-1831,
Unique-ID = ISI:000227714700002,
2003
P. Jurecka and P. Hobza, "True stabilization energies for the optimal planar hydrogen-bonded and
stacked structures of guanine center dot center dot center dot cytosine,
adenine center dot center dot center dot thymine, and their 9-and
1-methyl derivatives: Complete basis set calculations at the MP2 and
CCSD(T) levels and comparison with experiment," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 125, iss. 50, pp. 15608-15613, 2003.
[Bibtex]
@article ISI:000187208300055,
Author = Jurecka, P and Hobza, P,
Title = True stabilization energies for the optimal planar hydrogen-bonded and
stacked structures of guanine center dot center dot center dot cytosine,
adenine center dot center dot center dot thymine, and their 9-and
1-methyl derivatives: Complete basis set calculations at the MP2 and
CCSD(T) levels and comparison with experiment,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2003,
Volume = 125,
Number = 50,
Pages = 15608-15613,
Month = DEC 17,
Abstract = Planar H-bonded and stacked structures of guanine(...)cytosine
(G(...)C), adenine(...)thymine (A(...)T),
9-methylguanine(...)1-methylcytosine (mG(...)mC), and
9-methyladenine(...)1-methylthymine (mA(...)mT) were optimized at the
RI-MP2 level using the TZVPP ([5s3p2d1f/3s2p1d]) basis set. Planar
H-bonded structures of G(...)C, mG(...)mC, and A(...)T correspond to the
Watson-Crick (WC) arrangement, in contrast to mA(...)mT for which the
Hoogsteen (H) structure is found. Stabilization energies for all
structures were determined as the sum of the complete basis set limit of
MP2 energies and a (DeltaE(CCSD(T)) - DeltaE(MP2)) correction term
evaluated with the cc-pVDZ(0.25,0.15) basis set. The complete basis set
limit of MP2 energies was determined by two-point extrapolation using
the aug-cc-pVXZ basis sets for X = D and T and X = T and Q. This
procedure is required since the convergency of the MP2 interaction
energy for the present complexes is rather slow, and it is thus
important to include the extrapolation to the complete basis set limit.
For the MP2/aug-cc-pVQZ level of theory, stabilization energies for all
complexes studied are already very close to the complete basis set
limit. The much cheaper D-->T extrapolation provided a complete basis
set limit close (by less than 0.7 kcal/mol) to the more accurate T-->Q
term, and the D-->T extrapolation can be recommended for evaluation of
complete basis set limits of more extended complexes (e.g. larger motifs
of DNA). The convergency of the (DeltaE(CCSD(T)) - DeltaE(MP2)) term is
known to be faster than that of the MP2 or CCSD(T) correlation energy
itself, and the cc-pVDZ(0.25,0.15) basis set provides reasonable values
for planar H-bonded as well as stacked structures. Inclusion of the
CCSD(T) correction is essential for obtaining reliable relative values
for planar H-bonding and stacking interactions; neglecting the CCSD(T)
correction results in very considerable errors between 2.5 and 3.4
kcal/mol. Final stabilization energies (kcal/mol) for the base pairs
studied are very substantial (A(...)T WC, 15.4; mA(...)mT H, 16.3;
A(...)T stacked, 11.6; mA(...)mT stacked, 13.1; G(...)C WC, 28.8;
mG(...)mC WC, 28.5; G(...)C stacked, 16.9; mG(...)mC stacked, 18.0),
much larger than published previously. On the basis of comparison with
experimental data, we conclude that our values represent the lower
boundary of the true stabilization energies. On the basis of error
analysis, we expect the present H-bonding energies to be fairly close to
the true values, while stacked energies are still expected to be about
10\% too low. The stacking energy for the mG(...)mC pair is considerably
lower than the respective H-bonding energy, but it is larger than the
mA(...)mT H-bonding energy. This conclusion could significantly change
the present view on the importance of specific H-bonding interactions
and nonspecific stacking interactions in nature, for instance, in DNA.
Present stabilization energies for H-bonding and stacking energies
represent the most accurate and reliable values and can be considered as
new reference data.,
DOI = 10.1021/ja036611j,
ISSN = 0002-7863,
Unique-ID = ISI:000187208300055,
F. Ryjacek, T. Kubar, and P. Hobza, "New parameterization of the Cornell et al. empirical force field
covering amino group nonplanarity in nucleic acid bases," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 24, iss. 15, pp. 1891-1901, 2003.
[Bibtex]
@article ISI:000185991300008,
Author = Ryjacek, F and Kubar, T and Hobza, P,
Title = New parameterization of the Cornell et al. empirical force field
covering amino group nonplanarity in nucleic acid bases,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 2003,
Volume = 24,
Number = 15,
Pages = 1891-1901,
Month = NOV 30,
Abstract = The Cornell et al. empirical potential (Cornell et al., J Am Chem Soc
1995, 117, 5197) was modified by the introduction of nonplanarity of the
amino group in guanine, adenine, and cytosine. Reparameterization was
performed for 12 bond parameters of the amino group (three valence
angles (C-N-H-1, C-N-H-2, and H-1-N-H-2) and the improper dihedral angle
at nitrogen, four dihedral angles (X-C-N-H-1, Y-C-N-H-2, X-X-C-N,
Y-Y-C-N), three valence angles (X-C-N, Y-C-N, X-C-Y), and the improper
dihedral angle at the adjacent carbon), and was based on correlated ab
initio potential energy surfaces. Calculations were performed using the
resolution of identity MP2 (RIMP2) method with SVP (3s2p1d/2s1p), TZVP
(5s3p1d/3s1p), TZVPP (5s3p2d1f/3s2p1d), and augTZVPP (6s4p3d2f/4s3p2d)
basis sets. Results obtained on the latter two levels are practically
identical with the literature reference data [MP2/6-311 + +G(2df,p)]
and the RIMP2/augTZVPP data can be considered a new reference set. The
potential energy surface used for reparameterization was evaluated at
the RIMP2/SVP level because respective geometry as well as energy data
were close to the reference ones, and the computational time was very
favorable. The modified potential was tested for 19 H-bonded and eight
stacked nucleic acid base pairs. Interaction energies as well as
geometries were described by the modified potential considerably better
than by the original one and significant improvement resulted in the
description of the nonplanar H-bonded and stacked complexes. (C) 2003
Wiley Periodicals, Inc.,
DOI = 10.1002/jcc.10352,
ISSN = 0192-8651,
Unique-ID = ISI:000185991300008,
P. Slavicek, R. Kalus, P. Paska, I. Odvarkova, P. Hobza, and A. Malijevsky, "State-of-the-art correlated ab initio potential energy curves for heavy
rare gas dimers: Ar-2, Kr-2, and Xe-2," JOURNAL OF CHEMICAL PHYSICS, vol. 119, iss. 4, pp. 2102-2119, 2003.
[Bibtex]
@article ISI:000184103000027,
Author = Slavicek, P and Kalus, R and Paska, P and Odvarkova, I and Hobza, P and
Malijevsky, A,
Title = State-of-the-art correlated ab initio potential energy curves for heavy
rare gas dimers: Ar-2, Kr-2, and Xe-2,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 2003,
Volume = 119,
Number = 4,
Pages = 2102-2119,
Month = JUL 22,
Abstract = Characteristics of the heavy rare gas dimers (Ar-2,Kr-2,Xe-2) have been
studied by correlated ab initio calculations. All-electron CCSD(T)
calculations were performed for Ar and Kr dimers, and calculations with
relativistic effective core potentials were performed for Kr and Xe
dimers. Extended basis sets (aug-cc-pVXZ, X=D, T, Q, 5, 6) were combined
with bond functions (spd, spdfg). The use of bond functions
significantly improves the basis set convergence. For the argon dimer,
we have included also a CCSDT correction yielding a higher quality
potential energy curve. This correction has been calculated using
aug-cc-pVTZ+spd basis set. All possible sources of errors have been
analyzed for the argon dimer [basis set saturation, correlation
contributions going beyond CCSD(T) method, effect of core corrections
and relativistic corrections]. In the case of the Ar dimer, the highest
level of theory reproduces the semiempirical stabilization energy within
1.3 cm(-1). To obtain even closer agreement with experiment it would be
necessary to fully include quadruple and higher excitations as well as
to account properly for the core corrections with yet unpublished core
oriented basis sets. Further improvement of one electron basis set will
not lead to a better agreement with experiment. In the case of the other
two dimers, the agreement between theory and experiment is also
acceptable but not quantitative as in the case of the Ar dimer.
Apparently, current calculations are close to the basis set limit and
better agreement can only be obtained by proper covering of
contributions mentioned for the argon dimer. The newly developed ECP
oriented aug-cc-pVXZ basis set is very effective and can be recommended
for high level calculations of molecular clusters containing heavier
rare gas elements. The fast DZ/TZ extrapolation technique has been
extended so that the use of empirical parameters can be avoided. Results
obtained by extrapolations with medium size basis sets are surprisingly
close to the most accurate ones. Further, the MP2-CCSD(T) difference was
shown to be much less dependent on the size of the basis set than the
energies themselves. These two conditions allow to construct the true
stabilization energy of extended complexes as a sum of extrapolated
complete basis set limit of MP2 stabilization energy and [MP2-CCSD(T)]
term determined in a smaller basis set. The ab initio pair
intermolecular potential results have been fitted to suitably chosen
analytical formulas, and tested on experimental data for the second
virial coefficients, spectral characteristics, and scattering data. For
argon, an excellent agreement between the theoretical and the
experimental values has been found. In the case of krypton and xenon the
agreement is not as good but still acceptable. (C) 2003 American
Institute of Physics.,
DOI = 10.1063/1.1582838,
ISSN = 0021-9606,
Unique-ID = ISI:000184103000027,
M. Hanus, F. Ryjacek, M. Kabelac, T. Kubar, T. Bogdan, S. Trygubenko, and P. Hobza, "Correlated ab initio study of nucleic acid bases and their tautomers in
the gas phase, in a microhydrated environment and in aqueous solution.
Guanine: Surprising stabilization of rare tautomers in aqueous solution," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 125, iss. 25, pp. 7678-7688, 2003.
[Bibtex]
@article ISI:000183646400045,
Author = Hanus, M and Ryjacek, F and Kabelac, M and Kubar, T and Bogdan, TV and
Trygubenko, SA and Hobza, P,
Title = Correlated ab initio study of nucleic acid bases and their tautomers in
the gas phase, in a microhydrated environment and in aqueous solution.
Guanine: Surprising stabilization of rare tautomers in aqueous solution,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2003,
Volume = 125,
Number = 25,
Pages = 7678-7688,
Month = JUN 25,
Abstract = Altogether eight keto and enol tautomers of guanine were studied
theoretically in the gas phase, in a microhydrated environment (1 and 2
water molecules) and in bulk water. The structures of isolated, as well
as mono- and dihydrated tautomers were determined by means of the
RI-MP(2) method using the extended TZVPP (5s3p2d1f/3s2p1d) basis set.
The relative energies of isolated tautomers included the correction to
higher correlation energy terms evaluated at the CCSD(T)/aug-cc-pVDZ
level. The relative enthalpies at 0 K and relative free energies at 298
K were based on the above-mentioned relative energies and zero-point
vibration energies, temperature-dependent enthalpy terms and entropies
evaluated at the MP2/6-31G** level. The keto form having hydrogen
atom at N7 is the global minimum while the canonical form having
hydrogen atom at N9 represents the first local minimum at all
theoretical levels in vacuo and in the presence of 1 and 2 water
molecules. All three unusual rare tautomers having hydrogens at N3 and
N7, at N3 and N9, and also at N9 and N7 are systematically considerably
less stable and can be hardly detected in the gas phase. The theoretical
predictions fully agree with existing theoretical as well as
experimental results. The effect of bulk solvent on the relative
stability of guanine tautomers was studied by self-consistent reaction
field and molecular dynamics free energy calculations using the
thermodynamic integration method. Bulk solvent, surprisingly, strongly
favored these three rare tautomers over all remaining low-energy
tautomers and probably only these forms can exist in water phase. The
global minimum (tautomer with hydrogens at N3 and N7) is by 13 kcal/mol
more stable than the canonical form (3rd local minimum). Addition of one
or two water molecules does not change the relative stability order of
isolated guanine tautomers but the respective trend clearly supports the
surprising stabilization of three rare forms.,
DOI = 10.1021/ja034245y,
ISSN = 0002-7863,
Unique-ID = ISI:000183646400045,
P. Wojciechowski, W. Zierkiewicz, D. Michalska, and P. Hobza, "Electronic structures, vibrational spectra, and revised assignment of
aniline and its radical cation: Theoretical study," JOURNAL OF CHEMICAL PHYSICS, vol. 118, iss. 24, pp. 10900-10911, 2003.
[Bibtex]
@article ISI:000183402200009,
Author = Wojciechowski, PM and Zierkiewicz, W and Michalska, D and Hobza, P,
Title = Electronic structures, vibrational spectra, and revised assignment of
aniline and its radical cation: Theoretical study,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 2003,
Volume = 118,
Number = 24,
Pages = 10900-10911,
Month = JUN 22,
Abstract = Comprehensive studies of the molecular and electronic structures,
vibrational frequencies, and infrared and Raman intensities of the
aniline radical cation, C6H5NH2+ have been performed by using the
unrestricted density functional (UB3LYP) and second-order Moller-Plesset
(UMP2) methods with the extended 6-311++G(df,pd) basis set. For
comparison, analogous calculations were carried out for the closed-shell
neutral aniline. The studies provided detailed insight into the bonding
changes that take place in aniline upon ionization. The natural bond
orbital (NBO) analysis has revealed that the ppi-radical conjugative
interactions are of prime importance in stabilizing the planar,
quinoid-type structure of the aniline radical cation. It is shown that
the natural charges calculated for aniline are consistent with the
chemical properties of this molecule (an ortho- and para-directing power
of the NH2 group in electrophilic substitutions), whereas Mulliken
charges are not reliable. The theoretical vibrational frequencies of
aniline, calculated by the B3LYP method, show excellent agreement with
the available experimental data. In contrast, the MP2 method is
deficient in predicting the frequencies of several modes in aniline,
despite the use of the extended basis set in calculations. The
frequencies of aniline radical cation, calculated at the
UB3LYP/6-311++G(df,pd) level, are in very good agreement with the
recently reported experimental data from zero kinetic energy
photoelectron and infrared depletion spectroscopic studies. The clear-
cut assignment of the IR and Raman spectra of the investigated molecules
has been made on the basis of the calculated potential energy
distributions. Several bands in the spectra have been reassigned. It is
shown that ionization of aniline can be easily identified by the
appearance of the very strong band at about 1490 cm(-1), in the Raman
spectrum. The redshift of the N-H stretching frequencies and the
blueshift of the C-H stretching frequencies are observed in aniline,
upon ionization. As revealed by NBO analysis, the frequency shifts can
be correlated with the increase of electron density (ED) on the
antibonding orbitals (sigma(NH)*) and decrease of ED on sigma(CH)*,
respectively. These effects are associated with a weakening of N-H bonds
and strengthening of C-H bonds in the aniline radical cation. The
simulated theoretical Raman and infrared spectra of aniline and its
radical cation, reported in this work, can be used in further
spectroscopic studies of their van der Waals clusters and hydrogen
bonded complexes. (C) 2003 American Institute of Physics.,
DOI = 10.1063/1.1574788,
ISSN = 0021-9606,
Unique-ID = ISI:000183402200009,
J. Braun, H. Neusser, and P. Hobza, "N-H center dot center dot center dot pi interactions in indole center
dot center dot center dot benzene-h(6),d(6) and indole center dot center
dot center dot benzene-h(6),d(6) radical cation complexes. Mass analyzed
threshold ionization experiments and correlated ab initio quantum
chemical calculations," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 107, iss. 19, pp. 3918-3924, 2003.
[Bibtex]
@article ISI:000182893900044,
Author = Braun, J and Neusser, HJ and Hobza, P,
Title = N-H center dot center dot center dot pi interactions in indole center
dot center dot center dot benzene-h(6),d(6) and indole center dot center
dot center dot benzene-h(6),d(6) radical cation complexes. Mass analyzed
threshold ionization experiments and correlated ab initio quantum
chemical calculations,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2003,
Volume = 107,
Number = 19,
Pages = 3918-3924,
Month = MAY 15,
Abstract = Indole-benzene complexes in the neutral and cationic forms were
investigated by resonance enhanced two-photon ionization (REMPI) and
mass analyzed threshold ionization (MATI) experiments and nonempirical
ab initio quantum chemical methods. The experiment yields vibrational
frequencies of the ionized complex in its ionic ground state. In
addition, by observing the breakdown of the MATI signal at the cluster
ion mass for a certain internal energy and its simultaneous appearance
at the fragment mass, the dissociation energy of the ionic complex is
found with high precision. Using a thermochemical cycle from this and
the also measured adiabatic ionization energies of indole-benzene and
indole, the dissociation energy of the neutral complex is found. The
data were recently presented for indole-benzene-h(6) and are shown for
indole-benzene-d(6) for the first time in this work. Stacked and
N-H...pi H-bonded structures of the neutral dimer were optimized using
the approximative resolution of identity MP2 (RI-MP2) method combined
with extended basis. The RI-MP2 treatment showed the preferential
stability of the stacked structure while the CCSD(T) calculations favor
the N-H...pi H-bonded structure. The final stabilization enthalpy
estimate (5.3 kcal/mol) agreed nicely with the experimental value of 5.2
kcal/mol (1823 +/- 15 cm(-1)) and points clearly to a N-H...pi bounded
structure of the complex. In the case of a radical cation, the stacked
structure was shown not to be stable and was converted during
optimization to the N-H...pi H-bonded structure. The final stabilization
enthalpy estimate (12.8 kcal/mol) agreed reasonably well with the
experimental value of 13.1 kcal/mol (4581 10 cm(-1)). The theoretical
harmonic intermolecular stretch frequency obtained for the neutral and
cationic complexes (78 and 105 cm(-1)) agreed fairly well with the
experimental values (70 and 95 cm(-1)). A surprisingly large N-H...pi
stabilization energy calculated for the benzene...indole complex
supports speculation about the role of these interactions in the
biological environment. The excellent agreement of the experimental and
theoretical binding energies gives for the first time direct evidence
that the theoretical treatment used can yield stabilization energies
(enthalpies) of large molecular clusters differing from the experimental
values by less than 0.5 kcal/mol.,
DOI = 10.1021/jp027217v,
ISSN = 1089-5639,
Unique-ID = ISI:000182893900044,
D. Reha, M. Kabelac, F. Ryjacek, J. Sponer, J. Sponer, M. Elstner, S. Suhai, and P. Hobza, "Intercalators. 1. Nature of stacking interactions between intercalators
(Ethidium, Daunomycin, Ellipticine, and 4 `,6
`-diaminide-2-phenylindole) and DNA base pairs. Ab initio quantum
chemical, density functional theory, and empirical potential study (vol
124, pg 3366, 2002)," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 125, iss. 18, pp. 5581, 2003.
[Bibtex]
@article ISI:000182682700057,
Author = Reha, D and Kabelac, M and Ryjacek, F and Sponer, J and Sponer, JE and
Elstner, M and Suhai, S and Hobza, P,
Title = Intercalators. 1. Nature of stacking interactions between intercalators
(Ethidium, Daunomycin, Ellipticine, and 4 `,6
`-diaminide-2-phenylindole) and DNA base pairs. Ab initio quantum
chemical, density functional theory, and empirical potential study (vol
124, pg 3366, 2002),
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2003,
Volume = 125,
Number = 18,
Pages = 5581,
Month = MAY 7,
DOI = 10.1021/ja033983j,
ISSN = 0002-7863,
Unique-ID = ISI:000182682700057,
J. Chocholousova, J. Vacek, and P. Hobza, "Acetic acid dimer in the gas phase, nonpolar solvent, microhydrated
environment, and dilute and concentrated acetic acid: Ab initio quantum
chemical and molecular dynamics simulations," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 107, iss. 17, pp. 3086-3092, 2003.
[Bibtex]
@article ISI:000182490900014,
Author = Chocholousova, J and Vacek, J and Hobza, P,
Title = Acetic acid dimer in the gas phase, nonpolar solvent, microhydrated
environment, and dilute and concentrated acetic acid: Ab initio quantum
chemical and molecular dynamics simulations,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2003,
Volume = 107,
Number = 17,
Pages = 3086-3092,
Month = MAY 1,
Abstract = Theoretical study of the acetic acid dimer, its microhydration and its
behavior in water and chloroform solution was performed. To characterize
the system, we adopted ab initio methods at the DFT and RI MP2 (the
resolution of the identity approximation MP2) levels for the gas-phase
calculations, PCM (polarizable continuum model) approximation using the
polarizable conductor calculation model (COSMO) for description of
solvent, and constant energy (NVE) and constant temperature (NVT)
molecular dynamics simulations for gas phase and explicit solvent
calculations, respectively. The cyclic structure of the acetic acid
dimer is the most stable in the gas phase only. During microhydration,
the water molecules are incorporated in the dimer leading to
water-separated structures. This conclusion is based on ab initio
quantum chemical calculations, as well as on molecular dynamics
simulations. The fact that the cyclic structure does not appear in water
solution is in agreement with previous theoretical and experimental
results. Extending the search also on other acetic acid dimer
structures, we concluded that acetic acid does not form any dimer
structure in water solution. The cyclic structure is also supposed to be
stable in chloroform solution.,
DOI = 10.1021/jp027637k,
ISSN = 1089-5639,
Unique-ID = ISI:000182490900014,
E. Mrazkova and P. Hobza, "Hydration of sulfo and methyl groups in dimethyl sulfoxide is
accompanied by the formation of red-shifted hydrogen bonds and improper
blue-shifted hydrogen bonds: An ab initio quantum chemical study," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 107, iss. 7, pp. 1032-1039, 2003.
[Bibtex]
@article ISI:000181100400012,
Author = Mrazkova, E and Hobza, P,
Title = Hydration of sulfo and methyl groups in dimethyl sulfoxide is
accompanied by the formation of red-shifted hydrogen bonds and improper
blue-shifted hydrogen bonds: An ab initio quantum chemical study,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2003,
Volume = 107,
Number = 7,
Pages = 1032-1039,
Month = FEB 20,
Abstract = In this study, the hydration of dimethyl sulfoxide was investigated by
means of molecular dynamics (MD) simulations and quantum chemical
correlated ab initio calculations. MD simulations show the hydration
sites when the systems are exposed to 1, 3, 6, 16, and 32 water
molecules. Various DMSO...(H2O)(n) (n = 1-3) complexes where waters
hydrate sulfo and methyl groups were then reoptimized at the ab initio
level. The hydration of DMSO leads to an elongation of the S=O bond and
a contraction of methyl C-H bonds. Whereas the elongation of the S=O
bond is accompanied by a red shift of the respective stretch frequency,
the contraction of the C-H bonds gives a blue shift to the C-H stretch
frequencies. The former effect is easily explained by the transfer of
electron density to the antibonding orbitals of the S=O bond, yielding
its weakening. Various mechanisms leading to the contraction of the
methyl CH bonds were suggested. They were based on secondary geometry
changes originating from the significant elongation of the S=O bond and
also on the changes of the electron density in DMSO upon complexation,
resulting in a rehybridization of the CH bonds. The influence of the
electrostatic field of hydrating waters was also considered. Predicted
frequency shifts fully agree with the observed data. Also, the observed
blue shift increase occurring as a consequence of progressive hydration
was interpreted theoretically, and the mechanisms of this phenomenon are
suggested.,
DOI = 10.1021/jp026895e,
ISSN = 1089-5639,
Unique-ID = ISI:000181100400012,
N. Spackova, T. Cheatham, F. Ryjacek, F. Lankas, L. van Meervelt, P. Hobza, and J. Sponer, "Molecular dynamics simulations and thermodynamics analysis of DNA-drug
complexes. Minor groove binding between 4 `,6-diamidino-2-phenylindole
and DNA duplexes in solution," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 125, iss. 7, pp. 1759-1769, 2003.
[Bibtex]
@article ISI:000181088000025,
Author = Spackova, N and Cheatham, TE and Ryjacek, F and Lankas, F and van
Meervelt, L and Hobza, P and Sponer, J,
Title = Molecular dynamics simulations and thermodynamics analysis of DNA-drug
complexes. Minor groove binding between 4 `,6-diamidino-2-phenylindole
and DNA duplexes in solution,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2003,
Volume = 125,
Number = 7,
Pages = 1759-1769,
Month = FEB 19,
Abstract = An extended set of nanosecond-scale molecular dynamics simulations of
DNA duplex sequences in explicit solvent interacting with the minor
groove binding drug 4',6-diamidino-2-phenylindole (DAPI) are
investigated for four different and sequence specific binding modes.
Force fields for DAPI have been parametrized to properly reflect its
internal nonplanarity. Sequences investigated include the binding modes
observed experimentally, that is, (AATT) under bar in d(CGCGAATTCGCG)(2)
and (ATTG) under bar in d(GGCCAATTGG)(2) and alternative shifted binding
modes (ATTC) under bar and (AATT) under bar, respectively. In each case,
stable MD simulations are obtained, well reproducing specific hydration
patterns seen in the experiments. In contrast to the 2.4 Angstrom
d(CGCGAATTCGCG)(2) crystal structure, the DAPI is nonplanar, consistent
with its gas-phase geometry and the higher resolution crystal structure.
The simulations also suggest that the DAPI molecule is able to adopt
different conformational substates accompanied by specific hydration
patterns that include long-residing waters. The MM-PBSA technology for
estimating relative free energies was utilized. The most consistent free
energy results were obtained with an approach that uses a single
trajectory of the, DNA-DAPI complex to estimate all free energy terms.
It is demonstrated that explicit inclusion of a subset of bound water
molecules shifts the calculated relative binding free energies in favor
of both crystallographically observed binding modes, underlining the
importance of structured hydration.,
DOI = 10.1021/ja025660d,
ISSN = 0002-7863,
Unique-ID = ISI:000181088000025,
J. Sponer and P. Hobza, "Molecular interactions of nucleic acid bases. A review of
quantum-chemical studies," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 68, iss. 12, pp. 2231-2282, 2003.
[Bibtex]
@article ISI:000187207300001,
Author = Sponer, J and Hobza, P,
Title = Molecular interactions of nucleic acid bases. A review of
quantum-chemical studies,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 2003,
Volume = 68,
Number = 12,
Pages = 2231-2282,
Abstract = Ab initio quantum-chemical calculations with inclusion of electron
correlation significantly contributed to our understanding of molecular
interactions of DNA and RNA bases. Some of the most important findings
are introduced in the present overview: structures and energies of
hydrogen bonded base pairs, nature of base stacking, interactions
between metal cations and nucleobases, nonplanarity of isolated
nucleobases and other monomer properties, tautomeric equilibria of
nucleobases, out-of-plane hydrogen bonds and amino acceptor
interactions. The role of selected molecular interactions in nucleic
acids is discussed and representative examples where these interactions
occur are given. Also, accuracy of density functional theory,
semiempirical methods, distributed multipole analysis and empirical
potentials is commented on. Special attention is given to our very
recent reference calculations on base stacking and H-bonding. Finally,
we briefly comment on the relationship between advanced ab initio
quantum-chemical methods and large-scale explicit solvent molecular
dynamics simulations of nucleic acids.,
DOI = 10.1135/cccc20032231,
ISSN = 0010-0765,
Unique-ID = ISI:000187207300001,
P. Hobza and V. Spirko, "Why is the N-1-H stretch vibration frequency of guanine shifted upon
dimerization to the red and the amino N-H stretch vibration frequency to
the blue?," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 5, iss. 6, pp. 1290-1294, 2003.
[Bibtex]
@article ISI:000181288700045,
Author = Hobza, P and Spirko, V,
Title = Why is the N-1-H stretch vibration frequency of guanine shifted upon
dimerization to the red and the amino N-H stretch vibration frequency to
the blue?,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2003,
Volume = 5,
Number = 6,
Pages = 1290-1294,
Abstract = Three isomers of the guanine dimer (K9K9-1, K9K7-1 and K7K7-1)
possessing two N-H...O=C H-bonds were investigated theoretically using
the ab initio calculations at the HF/6-31G** level. Amino groups in
these isomers were not directly involved in H-bonding. Besides the red
shifts of the N-H stretch vibrations (supporting the H-bonded character
of these contacts) an unexpected blue shift of amino N-H stretch
vibrations was found and this conclusion fully agrees with published
experimental results. The blue shift of the amino group N-H stretch
vibrations in all guanine dimer structures was clarified by the
planarization of the guanine amino group. Absolute values of harmonic
amino N-H stretch frequencies and their shifts upon planarization were
verified by performing the two-dimensional anharmonic vibrational
analysis. The planarization of the guanine amino group cannot be
interpreted on the basis of an electrostatic model and is due to
redistribution of electron density in subsystems upon dimerization. The
redistribution occurred at the aromatic ring as well as at the amino
group nitrogen and leads to formation of a new resonant state. The
electron density decrease in the lone electron pair of amino nitrogen
gives rehybridization of the respective atomic orbitals (change from the
sp(3) to the sp(2) state). The (amino) H...O=C contacts can be thus
described as an improper, blue-shifting H-bond. An increased amino N-H
stretch frequency represents the fingerprint of the planarization of the
guanine amino group and is the first spectroscopic manifestation of the
fact that the amino group in nucleic acid bases is nonplanar. Blue
shifts of the amino N-H stretch frequencies occurred only if the amino
group is bifurcated. The guanine dimer is the first complex where one
proton acceptor (C=O group) is simultaneously connected with two proton
donors (NH and NH2) by H-bond and improper, blue-shifting H-bond.,
DOI = 10.1039/b210223d,
ISSN = 1463-9076,
Unique-ID = ISI:000181288700045,
V. Sychrovsky, B. Schneider, P. Hobza, L. Zidek, and V. Sklenar, "The effect of water on NMR spin-spin couplings in DNA: Improvement of
calculated values by application of two solvent models," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 5, iss. 4, pp. 734-739, 2003.
[Bibtex]
@article ISI:000181278300011,
Author = Sychrovsky, V and Schneider, B and Hobza, P and Zidek, L and Sklenar, V,
Title = The effect of water on NMR spin-spin couplings in DNA: Improvement of
calculated values by application of two solvent models,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2003,
Volume = 5,
Number = 4,
Pages = 734-739,
Abstract = Influence of water on isotropic one-bond (1)J(X,H), (1)J(C,X) and
two-bond (2)J(X H), (X = C,N) indirect NMR spin-spin coupling constants
were investigated theoretically at ab initio levels by application of
explicit and PCM solvent models. Sensitivity of the Fermi contact
contribution to the total J coupling towards the solvent inclusion
calculated using coupled perturbed density functional theory with the
B3LYP hybrid functional is dominating, while solvent shifts of the other
three J contributions are negligible. Consideration of the solvent leads
to a noticeable shift of the (1)J(C,H) couplings; the largest shift of
6.1 Hz was found for (1)J(C8,H8) coupling in guanine. Further inclusion
of solvent decreases the mean absolute deviation between the calculated
and experimental J constants from 1.7 to 1.1 Hz for guanine, from 2.4 to
0.6 Hz for cytosine, and from 2.3 to 1.6 Hz for adenine. In the explicit
solvent model, the (1)J(C8,H8) solvent shift seems to be sensitive to
the magnitude of charge transfer from water sigma bonding O-H and oxygen
lone pair orbitals to the sigma* antibonding C8-H8, C8-N7, and C8-N9
orbitals of guanine. Both explicit and PCM solvent models provide
similar improvement of calculated couplings when comapred to the
experimental data of the C-13, N-15-labeled DNA hairpin molecule
d(GCGAAGC).,
DOI = 10.1039/b210553e,
ISSN = 1463-9076,
Unique-ID = ISI:000181278300011,
2002
P. Hobza and Z. Havlas, "Improper, blue-shifting hydrogen bond," THEORETICAL CHEMISTRY ACCOUNTS, vol. 108, iss. 6, pp. 325-334, 2002.
[Bibtex]
@article ISI:000180617400002,
Author = Hobza, P and Havlas, Z,
Title = Improper, blue-shifting hydrogen bond,
Journal = THEORETICAL CHEMISTRY ACCOUNTS,
Year = 2002,
Volume = 108,
Number = 6,
Pages = 325-334,
Month = DEC,
Abstract = The spectral manifestation and the nature of improper, blue-shifting
hydrogen-bonded complexes are entirely different from those of standard
hydrogen-bonded complexes. While the latter class of complexes is
characterized by an elongation of the X-H bond and a concomitant red
shift of the respective stretch frequency, a contraction of the X-H bond
and a blue shift of the X-H stretch frequency are typical for the former
class of complexes. Both classes of complexes exhibit electron-density
transfer from the proton acceptor to the proton donor. In the case of
hydrogen-bonded complexes, the electron-density transfer is mostly
larger then in the improper complexes. The role of the charge transfer
and electrostatic interaction is discussed. The importance of the charge
transfer is documented by natural bond orbital analysis, orbital
interaction diagrams, and by the insufficient description of the
interaction by the electrostatic model only.,
DOI = 10.1007/s00214-002-0367-5,
ISSN = 1432-881X,
Unique-ID = ISI:000180617400002,
J. Chocholousova, J. Vacek, F. Huisken, O. Werhahn, and P. Hobza, "Stacked structure of the glycine dimer is more stable than the cyclic
planar geometry with two O-H center dot center dot center dot O hydrogen
bonds: Concerted action of empirical, high-level nonempirical ab initio,
and experimental studies," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 106, iss. 47, pp. 11540-11549, 2002.
[Bibtex]
@article ISI:000179543600016,
Author = Chocholousova, J and Vacek, J and Huisken, F and Werhahn, O and Hobza, P,
Title = Stacked structure of the glycine dimer is more stable than the cyclic
planar geometry with two O-H center dot center dot center dot O hydrogen
bonds: Concerted action of empirical, high-level nonempirical ab initio,
and experimental studies,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2002,
Volume = 106,
Number = 47,
Pages = 11540-11549,
Month = NOV 28,
Abstract = The potential energy surface of the glycine dimer was investigated by
the molecular dynamics/quenching method. A new empirical potential
(EP1), largely based on the standard AMBER force field of Cornell et al.
(Cornell, W. D.; Cieplak, P.; Bayly, C. I.; Gould, I. R.; Merz, K. M.;
Ferguson, D. M:; Spellmeyer, D. C.; Fox, T.; Caldwell, J. E.; Kollman,
P. J. Am. Chem. Soc. 1995, 117, 5179), was introduced. It employs atomic
polarizabilities and RESP/B3LYP/aug-cc-pVTZ atomic charges and well
mimics the high-level ab initio PES of the glycine dimer. Surprisingly,
the most stable structure of the glycine dimer determined with the EP1
potential does not correspond to the planar cyclic structure with two
O-H...O hydrogen bonds (C1) but to a stacked arrangement (S1). The
stabilization energies of the 22 lowest-energy isomers of the glycine
dimer were recalculated at the MP2/6-31G** level of theory, and the
largest difference was found for the C1 and S1 structures. While the
empirical potential favored the S1 structure by 3 kcal/mol, the
correlated ab initio MP2/6-31G** calculations preferred the C1
structure by 2 kcal/mol. Applying higher levels of ab initio
calculations (countrepoise corrected gradient optimization, larger basis
sets, CCSD, CCSD(T), and QCISD(T) methods), we found that both
structures are comparable in energy or that the stacked structure is
even slightly more stable. The finding that the cyclic C1 structure is
not the lowest energy configuration is in good agreement with IR
spectroscopic studies on glycine dimers trapped in liquid helium
droplets. All experimental spectra feature a strong absorption band in
the region of the free O-H stretch, indicating that both hydroxyl groups
cannot be hydrogen-bonded in the glycine dimer at the same time. Due to
fast (subnanosecond) cooling of the glycine dimer in the helium
droplets, it is also suggested that a T-shaped local minimum can be
preserved in the cluster.,
DOI = 10.1021/jp025925a,
ISSN = 1089-5639,
Unique-ID = ISI:000179543600016,
P. Hobza, "N-H center dot center dot center dot F improper blue-shifting H-bond," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 90, iss. 3, pp. 1071-1074, 2002.
[Bibtex]
@article ISI:000178441900009,
Author = Hobza, P,
Title = N-H center dot center dot center dot F improper blue-shifting H-bond,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 2002,
Volume = 90,
Number = 3,
Pages = 1071-1074,
Month = NOV 5,
Abstract = The MP2/6-31G** calculations reveal a different pattern of H-bonding
in F2NH...Y (Y = FH, OH2, NH2) complexes. Whereas the blue-shifted
H-bonding was found for F2NH...FH complex (the first known case of
N-H...Y improper blue-shifting H-bonding), standard H-bonding exists for
F2NH...OH, and F2NH...NH, complexes. A different character of H-bonding
is explained by natural bond orbital analysis showing a systematic
increase of electron density in the sigma* antibonding orbital of the
N-H bond as well as in the lone-electron pairs of fluorine atoms of
proton the acceptor. Whereas the former effect leads to elongation of
the N-H bond and a red shift of N-H stretch frequency, the latter effect
gives the opposite, that is, contraction of the N-H bond and a blue
shift of N-H stretch frequency. Existence of a red- or blue-shifted
H-bonding is explained by the dominance of the former or latter effect.
(C) 2002 Wiley Periodicals, Inc.,
DOI = 10.1002/qua.10313,
ISSN = 0020-7608,
Unique-ID = ISI:000178441900009,
P. Jurecka and P. Hobza, "On the convergence of the (Delta E-CCSD(T)-Delta E-MP2) term for
complexes with multiple H-bonds," CHEMICAL PHYSICS LETTERS, vol. 365, iss. 1-2, pp. 89-94, 2002.
[Bibtex]
@article ISI:000178835800013,
Author = Jurecka, P and Hobza, P,
Title = On the convergence of the (Delta E-CCSD(T)-Delta E-MP2) term for
complexes with multiple H-bonds,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 2002,
Volume = 365,
Number = 1-2,
Pages = 89-94,
Month = OCT 28,
Abstract = The MP2 and CCSD(T) interaction energies of the following cyclic
complexes were studied: formic acid dimer (FO-FO), formamide dimer
(FA-FA), formamidine dimer (FI-FI), formamide(...)formamidine complex
(FA-FI) and the formamidinoaldehyde(...)amidinoformamide (FL-AF)
complex. Various AO basis sets up to the cc-pVTZ were investigated. It
was shown that the (DeltaE(CCSD(T)) - DeltaE(MP2)) correction term
evaluated with the 6-31G* basis set is overestimated while rather
accurate values were obtained with 6-31G*(0.25) and cc-pVDZ (0.25,
0.15) basis sets. Because the latter one performs well also for stacked
complexes it can be recommended for evaluation of the correction term of
extended complexes possessing both H-bonded and stacked structures. (C)
2002 Published by Elsevier Science B.V.,
DOI = 10.1016/S0009-2614(02)01423-9,
ISSN = 0009-2614,
Unique-ID = ISI:000178835800013,
V. Sychrovsky, J. Vacek, P. Hobza, L. Zidek, V. Sklenar, and D. Cremer, "Exploring the structure of a DNA hairpin with the help of NMR spin-spin
coupling constants: An experimental and quantum chemical investigation," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 106, iss. 39, pp. 10242-10250, 2002.
[Bibtex]
@article ISI:000178273500038,
Author = Sychrovsky, V and Vacek, J and Hobza, P and Zidek, L and Sklenar, V and
Cremer, D,
Title = Exploring the structure of a DNA hairpin with the help of NMR spin-spin
coupling constants: An experimental and quantum chemical investigation,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2002,
Volume = 106,
Number = 39,
Pages = 10242-10250,
Month = OCT 3,
Abstract = A C-13, N-15-labeled DNA hairpin molecule of the sequence d(GCGAAGC) =
d(G1C2G3A4A5G6C7) was investigated by NMR spectroscopy to determine
one-bond and two-bond NMR spin-spin coupling constants (1)J(X, H) (X =
C, N), (1)J(C, X) (X = C, N), and 2J(X,H) (X = C,N). Measured J values
for the Watson-Crick (WC) base-pairs G1C7, G6C2, the mismatched
base-pair G3A5 and the unpaired base A4 were compared with calculated J
values to verify sign and magnitude. For the J-calculations, coupled
perturbed density functional theory, in connection with the B3LYP hybrid
functional and basis sets (9s5p1d/5s,1p)[6s,4p,1d/3s,1p] as well as
(11s,7p,2d/6s,2p)[7s,6p.2d/4s,2p], was employed to determine
diamagnetic spin-orbit, paramagnetic spin-orbit, Fermi contact, and
spin-dipolar contributions to the total isotropic coupling constant J.
Coupling constants (1)J(C,H) and (2)J(N,H) turn out to be very sensitive
to the position of C and N in the pyrimidine or purine rings and,
therefore, can be used for rapid structure determination. Coupling
constant (1)J(N1,C6) in G of GC clearly reflects the impact of H-bonding
by an increase from -6.5 (exp.: -7.5) to -10.7 (-12.7) Hz. The direct
investigation of H-bonding via the (2)J(N,N') coupling constants reveals
that these parameters depend on the distance R(N-N'), the bending angle
N-H.,N', and the degree of planarity at the H-donor group. Different
types of H-bonding were identified. H-bonding is weaker in AG and
therefore, leads to smaller changes in the J values of the bases A and G
upon pairing than in the case of the WC base-pair GC.,
DOI = 10.1021/jp020673z,
ISSN = 1520-6106,
Unique-ID = ISI:000178273500038,
P. Hobza and J. Sponer, "Toward true DNA base-stacking energies: MP2, CCSD(T), and complete basis
set calculations," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 124, iss. 39, pp. 11802-11808, 2002.
[Bibtex]
@article ISI:000178317100051,
Author = Hobza, P and Sponer, J,
Title = Toward true DNA base-stacking energies: MP2, CCSD(T), and complete basis
set calculations,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2002,
Volume = 124,
Number = 39,
Pages = 11802-11808,
Month = OCT 2,
Abstract = Stacking energies in low-energy geometries of pyrimidine, uracil,
cytosine, and guanine homodimers were determined by the MP2 and CCSD(T)
calculations utilizing a wide range of split-valence,
correlation-consistent, and bond-functions basis sets. Complete basis
set MP2 (CBS MP2) stacking energies extrapolated using aug-cc-pVXZ (X =
D, T, and for pyrimidine dimer Q) basis sets equal to -5.3, -12.3, and
-11.2 kcal/mol for the first three dimers, respectively. Higher-order
correlation corrections estimated as the difference between MP2 and
CCSD(T) stacking energies amount to 2.0, 0.7, and 0.9 kcal/mol and lead
to final estimates of the genuine stacking energies for the three dimers
of -3.4, -11.6, and -10.4 kcal/mol. The CBS MP2 stacking-energy estimate
for guanine dimer (-14.8 kcal/mol) was based on the 6-31G*(0.25) and
aug-cc-pVDZ calculations. This simplified extrapolation can be routinely
used with a meaningful accuracy around 1 kcal/mol for large aromatic
stacking clusters. The final estimate of the guanine stacking energy
after the CCSD(T) correction amounts to - 12.9 kcal/mol. The
MP2/6-31G*(0.25) method previously used as the standard level to
calculate aromatic stacking in hundreds of geometries of nucleobase
dimers systematically underestimates the base stacking by ca. 1.0-2.5
kcal/mol per stacked dimer, covering 75-90\% of the intermolecular
correlation stabilization. We suggest that this correction is to be
considered in calibration of force fields and other cheaper
computational methods. The quality of the MP2/6-31G*(0.25) predictions
is nevertheless considerably better than suggested on the basis of
monomer polarizability calculations. Fast and very accurate estimates of
the MP2 aromatic stacking energies can be achieved using the Rl-MP2
method. The CBS MP2 calculations and the CCSD(T) correction, when taken
together, bring only marginal changes to the relative stability of
H-bonded and stacked base pairs, with a slight shift of ca. 1 kcal/mol
in favor of H-bonding. We suggest that the present values are very close
to ultimate predictions of the strength of aromatic base stacking of DNA
and RNA bases.,
DOI = 10.1021/ja026759n,
ISSN = 0002-7863,
Unique-ID = ISI:000178317100051,
P. Hobza, C. Riehn, A. Weichert, and B. Brutschy, "Structure and binding energy of the phenol dimer: correlated ab initio
calculations compared with results from rotational coherence
spectroscopy," CHEMICAL PHYSICS, vol. 283, iss. 1-2, SI, pp. 331-339, 2002.
[Bibtex]
@article ISI:000178359200024,
Author = Hobza, P and Riehn, C and Weichert, A and Brutschy, B,
Title = Structure and binding energy of the phenol dimer: correlated ab initio
calculations compared with results from rotational coherence
spectroscopy,
Journal = CHEMICAL PHYSICS,
Year = 2002,
Volume = 283,
Number = 1-2, SI,
Pages = 331-339,
Month = OCT 1,
Abstract = Correlated ab initio calculations are compared with experimental data
from time-resolved rotational spectroscopy for the rotational constants
of the phenol dimer. This system poses a challenge to theory since both
hydrogen bonding and dispersion interaction are determining its unique
geometry. Excellent agreement is obtained at the RI-MP2/TZVPP level of
theory, demonstrating that higher order polarization functions are
necessary for an accurate structural description. The computed
intermolecular frequencies, stabilization energy and enthalpy are also
reported. (C) 2002 Elsevier Science B.V. All rights reserved.,
DOI = 10.1016/S0301-0104(02)00569-4,
ISSN = 0301-0104,
Unique-ID = ISI:000178359200024,
M. Stiborova, V. Simanek, E. Frei, P. Hobza, and J. Ulrichova, "DNA adduct formation from quaternary benzo[c]phenanthridine alkaloids
sanguinarine and chelerythrine as revealed by the P-32-postlabeling
technique," CHEMICO-BIOLOGICAL INTERACTIONS, vol. 140, iss. 3, pp. 231-242, 2002.
[Bibtex]
@article ISI:000178504400003,
Author = Stiborova, M and Simanek, V and Frei, E and Hobza, P and Ulrichova, J,
Title = DNA adduct formation from quaternary benzo[c]phenanthridine alkaloids
sanguinarine and chelerythrine as revealed by the P-32-postlabeling
technique,
Journal = CHEMICO-BIOLOGICAL INTERACTIONS,
Year = 2002,
Volume = 140,
Number = 3,
Pages = 231-242,
Month = AUG 15,
Abstract = Using the P-32-postlabeling assay, we investigated the ability of
quaternary benzo[c]phenanthridine alkaloids, sanguinarine,
chelerythrine and fagaronine, to form DNA adducts in vitro. Two enhanced
versions of the assay (enrichment by nuclease P1 and 1-butanol
extraction) were utilized in the study. Hepatic microsomes of rats
pre-treated with beta-naphthoflavone or those of uninduced rats, used as
metabolic activators, were incubated in the presence of calf thymus DNA
and the alkaloids, with NADPH used as a cofactor. Under these conditions
sanguinarine and chelerythrine, but not fagaronine, formed DNA adducts
detectable by P-32-postlabeling. DNA adduct formation by both alkaloids
was found to be concentration dependent. When analyzing different atomic
and bond indices of the C-11-C-12 bond (ring B) in alkaloid molecules we
found that fagaronine behaved differently from sanguinarine and
chelerythrine. While sanguinarine and chelerythrine showed a preference,
DOI = 10.1016/S0009-2797(02)00038-8,
ISSN = 0009-2797,
Unique-ID = ISI:000178504400003,
W. Zierkiewicz, D. Michalska, Z. Havlas, and P. Hobza, "Study of the nature of improper blue-shifting hydrogen bonding and
standard hydrogen bonding in the X3CH center dot center dot center dot
OH2 and XH center dot center dot center dot OH2 complexes (X = F, Cl,
Br, I): A correlated ab initio study," CHEMPHYSCHEM, vol. 3, iss. 6, pp. 511+, 2002.
[Bibtex]
@article ISI:000176393100005,
Author = Zierkiewicz, W and Michalska, D and Havlas, Z and Hobza, P,
Title = Study of the nature of improper blue-shifting hydrogen bonding and
standard hydrogen bonding in the X3CH center dot center dot center dot
OH2 and XH center dot center dot center dot OH2 complexes (X = F, Cl,
Br, I): A correlated ab initio study,
Journal = CHEMPHYSCHEM,
Year = 2002,
Volume = 3,
Number = 6,
Pages = 511+,
Month = JUN 17,
Abstract = From red to blue: Characteristic of classically understood hydrogen
bonding is a red shift in stretching frequency. However, a handful of
observations reported just the opposite, an improper blue-shifting
hydrogen bond. The theoretical calculations reported here on haloform -
water (see graphic) and hydrogen halide-water complexes reveals and
predicts the presence of both the classical and improper blue-shifting
hydrogen bonding.,
DOI = 10.1002/1439-7641(20020617)3:6<511::AID-CPHC511>3.0.CO;2-Y,
ISSN = 1439-4235,
Unique-ID = ISI:000176393100005,
elasticity of DNA polypurine tracts," BIOPHYSICAL JOURNAL, vol. 82, iss. 5, pp. 2592-2609, 2002.
[Bibtex]
@article ISI:000175259600028,
Author = Lankas, F and Cheatham, TE and Spackova, N and Hobza, P and Langowski, J
and Sponer, J,
Title = Critical effect of the N2 amino group on structure, dynamics, and
elasticity of DNA polypurine tracts,
Journal = BIOPHYSICAL JOURNAL,
Year = 2002,
Volume = 82,
Number = 5,
Pages = 2592-2609,
Month = MAY,
Abstract = Unrestrained 5-20-ns explicit-solvent molecular dynamics simulations
using the Cornell et al. force field have been carried out for
d[GCG(N)(11)GCG](2) (N, purine base) considering guanine.cytosine
(G.C), adenine.thymine (A.T), inosine.5-methyl-cytosine (I.mC), and
2-amino-adenine.thymine (D.T) basepairs. The simulations unambiguously
show that the structure and elasticity of N-tracts is primarily
determined by the presence of the amino group in the minor groove.
Simulated A-, I-, and AI-tracts show almost identical structures, with
high propeller twist and minor groove narrowing. G- and D-tracts have
small propeller twisting and are partly shifted toward the A-form. The
elastic properties also differ between the two groups. The
sequence-dependent electrostatic component of base stacking seems to
play a minor role. Our conclusions are entirely consistent with
available experimental data. Nevertheless, the propeller twist and
helical twist in the simulated A-tract appear to be underestimated
compared to crystallographic studies. To obtain further insight into the
possible force field deficiencies, additional multiple simulations have
been made for d(A)(10), systematically comparing four major force fields
currently used in DNA simulations and utilizing B and A-DNA forms as the
starting structure. This comparison shows that the conclusions of the
present work are not influenced by the force field choice.,
ISSN = 0006-3495,
Unique-ID = ISI:000175259600028,
D. Reha, M. Kabelac, F. Ryjacek, J. Sponer, J. Sponer, M. Elstner, S. Suhai, and P. Hobza, "Intercalators. 1. Nature of stacking interactions between intercalators
(ethidium, daunomycin, ellipticine, and 4 `,6-diaminide-2-phenylindole)
and DNA base pairs. Ab initio quantum chemical, density functional
theory, and empirical potential study," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 124, iss. 13, pp. 3366-3376, 2002.
[Bibtex]
@article ISI:000174793400036,
Author = Reha, D and Kabelac, M and Ryjacek, F and Sponer, J and Sponer, JE and
Elstner, M and Suhai, S and Hobza, P,
Title = Intercalators. 1. Nature of stacking interactions between intercalators
(ethidium, daunomycin, ellipticine, and 4 `,6-diaminide-2-phenylindole)
and DNA base pairs. Ab initio quantum chemical, density functional
theory, and empirical potential study,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2002,
Volume = 124,
Number = 13,
Pages = 3366-3376,
Month = APR 3,
Abstract = Properties of isolated intercalators (ethidium (E), daunomycin (D),
ellipticine (EL), and 4,6'-diaminide-2-phenylindole (DAPI)) and their
stacking interactions with adenine(...)thymine (AT) and
guanine(...)cytosine (GC) nucleic acid base pairs were investigated by
means of a nonempirical correlated ab initio method. All intercalators
exhibit large charge delocalization, and none of them (including the
DAPI dication) exhibits a site with dominant charge. All intercalators
have large polarizability and are good electron acceptors, while base
pairs are good electron donors. MP2/6-31G*(0.25) stabilization
energies of intercalator(...)base pair complexes are large (E(...)AT,
22.4 kcal/mol; D(...)GC, 17.8 kcal/mol; EL(...)GC, 18.2 kcal/mol;
DAPI(...)GC, 21.1 kcal/mol) and are well reproduced by modified AMBER
potential (van der Waals radii of intercalator atoms are enlarged and
their energy depths are increased). Standard AMBER potential
underestimates binding, especially for DAPI-containing complexes.
Because the DAPI dication is the best electron acceptor (among all
intercalators studied), this difference is explained by the importance
of the charge-transfer term, which is not included in the AMBER
potential. For the neutral EL molecule, the standard AMBER force field
provides correct results. The Hartree-Fock and DFT/B3LYP methods, not
covering the dispersion energy, fail completely to reveal any energy
minimum at the potential energy curve of the E(...)AT complex, and these
methods thus cannot be recommended for a study of intercalation process.
On the other hand, an approximate version of the DFT method, which was
extended to cover London dispersion energy, yields for all complexes
very good stabilization energies that are well comparable with
referenced ab initio data. Besides the vertical dependence of the
interaction, an energy twist dependence of the interaction energy was
also investigated by a reference correlated ab initio method and
empirical potentials. It is concluded that, despite the cationic (E + 1,
D + 1, DAPI + 2) or polar (EL) character of the intercalators
investigated, it is the dispersion energy which predominantly
contributes to the stability of intercalator(...)DNA base pair
complexes. Any procedure which does not cover dispersion energy is thus
not suitable for studying the process of intercalation.,
DOI = 10.1021/ja011490d,
ISSN = 0002-7863,
Unique-ID = ISI:000174793400036,
MOLECULES, SUPERMOLECULES, AND CRYSTALS, 2002, pp. 281-291.
[Bibtex]
@inproceedings ISI:000180113400015,
Author = Hobza, P,
Editor = Domenicano, A and Hargittai, I,
Title = Improper, blue-shifting hydrogen bond: Theory and experiment,
Booktitle = STRENGTH FROM WEAKNESS: STRUCTURAL CONSEQUENCES OF WEAK INTERACTIONS IN
MOLECULES, SUPERMOLECULES, AND CRYSTALS,
Series = NATO SCIENCE SERIES, SERIES II: MATHEMATICS, PHYSICS AND CHEMISTRY,
Year = 2002,
Volume = 68,
Pages = 281-291,
Note = NATO Advanced Research Workshop on Physical-Chemical Properties from
Weak Interactions, ERICE, ITALY, MAY 23-29, 2001,
Organization = NATO,
ISBN = 1-4020-0709-4,
Unique-ID = ISI:000180113400015,
J. Chocholousova, J. Vacek, and P. Hobza, "Potential energy and free energy surfaces of the formic acid dimer:
Correlated ab initio calculations and molecular dynamics simulations," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 4, iss. 11, pp. 2119-2122, 2002.
[Bibtex]
@article ISI:000175708800014,
Author = Chocholousova, J and Vacek, J and Hobza, P,
Title = Potential energy and free energy surfaces of the formic acid dimer:
Correlated ab initio calculations and molecular dynamics simulations,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2002,
Volume = 4,
Number = 11,
Pages = 2119-2122,
Abstract = A theoretical study of the potential energy surface ( PES) and free
energy surface (FES) of the formic acid dimer was performed. A constant
energy molecular dynamics/quenching technique was employed to scan the
PES and the results were compared with ab initio calculations at the MP2
and the resolution of the identity ( RI) approximation MP2 (RIMP2)
levels of theory. Long runs of molecular dynamics/quenching calculation
allowed us to evaluate the FES. Thermodynamic data for the six most
significantly populated structures of the formic acid dimer were
obtained within the rigid rotor harmonic oscillator ideal gas
approximation. The PES and FES of the formic acid dimer differ. The
first local minimum on the PES becomes the most populated structure at
higher temperature.,
DOI = 10.1039/b110872g,
ISSN = 1463-9076,
Unique-ID = ISI:000175708800014,
S. Trygubenko, T. Bogdan, M. Rueda, M. Orozco, F. Luque, J. Sponer, P. Slavicek, and P. Hobza, "Correlated ab initio study of nucleic acid bases and their tautomers in
the gas phase, in a microhydrated environment and in aqueous solution -
Part 1. Cytosine," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 4, iss. 17, pp. 4192-4203, 2002.
[Bibtex]
@article ISI:000177527500017,
Author = Trygubenko, SA and Bogdan, TV and Rueda, M and Orozco, M and Luque, FJ
and Sponer, J and Slavicek, P and Hobza, P,
Title = Correlated ab initio study of nucleic acid bases and their tautomers in
the gas phase, in a microhydrated environment and in aqueous solution -
Part 1. Cytosine,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2002,
Volume = 4,
Number = 17,
Pages = 4192-4203,
Abstract = Canonical, enol and imino tautomers of cytosine were studied
theoretically in the gas phase, in a microhydrated environment ( 1 and 2
waters) and in bulk water. The structures of isolated, mono- and
dihydrated tautomers were determined at the RI-MP2 level with the TZVPP
basis set. The relative energies of isolated tautomers were calculated
up to the CCSD( T) level using the cc-pVTZ basis set and at the MP2
level using the aug-cc-pVQZ basis set. For the MP2 and CCSD( T)
predictions, complete basis set estimates were obtained using various
extrapolation techniques. One of the enol forms is the global minimum at
all theoretical levels in the gas phase while the canonical form
represents the first local minimum. Already two water molecules reverse
the relative stability of these two tautomers making the canonical form
the global minimum. The effect of bulk solvent on the relative stability
of cytosine tautomers was examined from self-consistent reaction field,
Monte Carlo and molecular dynamics free energy calculations. Bulk
solvent calculations unambiguously favored the canonical tautomer over
the enol forms, in agreement with the trends found for the mono- and
dihydrated cluster model. However, the bulk solvent results for relative
energy changes differ from those of the cluster model. While the enol
structure is predicted to be the least stable species in the bulk
solvent, the microhydration model predicts it to be the first local
minimum with a rather small energy difference (similar to1 kcal mol(-1))
with respect to the global minimum.,
DOI = 10.1039/b202156k,
ISSN = 1463-9076,
Unique-ID = ISI:000177527500017,
[Bibtex]
@article ISI:000181759300002,
Author = Hobza, P,
Title = Parmenides in the context of the oral culture of the Antiquity,
Journal = FILOSOFICKY CASOPIS,
Year = 2002,
Volume = 50,
Number = 6,
Pages = 905-931,
Abstract = In my article I attempt to work out a new interpretation of Parmenides'
poem. The novelty of my approach is first that Parmenides' poem is not
interpreted with the help of ontology (in contrast to the current
conviction, I thus think that his poem has nothing to do with ontology),
and second that I place it in the spiritual and social context of
antiquity. The reason I attempt to interpret the poem without the help
of ontology is that all ontological interpretations eventually lead to a
number of paths, the interpretation of fragment B2, but mainly the
relationship of being (eon) and the sensual world. As for the poem
itself, my interpretation differs from the usual ones mainly in these
points: In contrast to all interpretations (known to me) I presuppose
that the poem does not consist of three, but of four, parts. I further
suppose that the poem only talks about two paths. It turns out the
supposition of two paths leads to a very clear and perspicuous
structuring (into four parts); the importance of this clear and
perspicuous structuring becomes distinctive especially when we realise
that Parmenides' poem was for public reading, i.e. oral reception. I
part with the common conception also in that I do not take the paths as
paths of ``discursive thinking'' but rather as paths through life; the
path is thus a metaphor for a way of life. As concerns the relation
between being and the sensual world, I think that this relation is
perspectival; it depends on the fact on which path we find ourselves: if
we follow the first, we see the world through reason (cf. leuse noo in B
4.1) as the only being; and if we follow the second we see various
things and thus the human, sensual, world. In the second part of my
article I attempt to place Parmenides' poem into the context of his
time, i.e. to the relation between oral institutions and to the
contemporary currents of thought.,
ISSN = 0015-1831,
Unique-ID = ISI:000181759300002,
(X=F,Cl)," in HIGH PERFORMANCE COMPUTING IN SCIENCE AND ENGINEERING 01, 2002, pp. 221-227.
[Bibtex]
@inproceedings ISI:000176238200021,
Author = Brutschy, B and Hobza, P,
Editor = Krause, E and Jager, W,
Title = Improper, blue-shifting hydrogen bond between fluorobenzene and CHX3
(X=F,Cl),
Booktitle = HIGH PERFORMANCE COMPUTING IN SCIENCE AND ENGINEERING 01,
Year = 2002,
Pages = 221-227,
Note = 4th Workshop on High Performance Computing in Science and Engineering,
STUTTGART, GERMANY, OCT 08-09, 2001,
Abstract = Weakly bonded 1:1 complexes between fluorobenzene (Fb) and fluoroform
(Ff) and chloroform (Chl) were investigated spectroscopically by
infrared ion-depletion spectroscopy (IR/R2PI) and theoretically by
correlated ab initio methods. CH stretches of the Fb.Ff complex are
blue-shifted by 12 cm(-1) and 21 cm(-1), respectively relative to the CH
stretch of isolated fluoroform. Each IR band is assigned to a different
hydrogen bonded fluorobenzene. fluoroform isomer. The isomer with the
most blue-shifted CH stretching vibration (21 cm(-1)) is assigned to a
sandwich type structure, exhibiting a CH hydrogen bond. In the case of
Fb.Chl only one structure (sandwich) exist for which blue-shift of 14
cm(-1) was found. The cluster structures have been calculated by
Counterpoise (CP)-corrected gradient optimization combined with
anharmonic vibrational analysis using the CP- corrected Hessians. The
predicted blue-shifts are 21 and 20.5 cm(-1) for the CH stretching
frequencies of fluoroform upon formation of a sandwich and a planar
structure respectively, and 12 cm(-1) for the CH stretching frequency of
chloroform. The theoretical and experimental shifts for both complexes
are thus well comparable. It is shown that the nature of the improper,
blue- shifting H-bond in these complexes differs from that in a standard
H-bond.,
ISBN = 3-540-42675-2,
Unique-ID = ISI:000176238200021,
2001
B. van der Veken, W. Herrebout, R. Szostak, D. Shchepkin, Z. Havlas, and P. Hobza, "The nature of improper, blue-shifting hydrogen bonding verified
experimentally," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 123, iss. 49, pp. 12290-12293, 2001.
[Bibtex]
@article ISI:000172645100020,
Author = van der Veken, BJ and Herrebout, WA and Szostak, R and Shchepkin, DN and
Havlas, Z and Hobza, P,
Title = The nature of improper, blue-shifting hydrogen bonding verified
experimentally,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2001,
Volume = 123,
Number = 49,
Pages = 12290-12293,
Month = DEC 12,
Abstract = In the infrared spectra of solutions in liquid argon of dimethyl ether
((CH3)(2)O) and fluoroform (HCF3), bands due to a 1:1 complex between
these monomers have been observed. The C-H stretch of the HCF3 moiety in
the complex appears 17.7 cm(-1) above that in the monomer, and its
intensity decreases by a factor of 11(2). These characteristics situate
the interaction between the monomers in the realm of improper,
blue-shifting hydrogen bonding. The complexation shifts the C-F
stretches downward by some 9 cm(-1), while the C-H stretches in
(CH3)(2)O are shifted upward by 9-15 cm(-1), and the C-O stretches are
shifted downward by 5 cm(-1). These shifts are in very good agreement
with those calculated by means of correlated ab initio methods, and this
validates a two-step mechanism for improper, blue-shifting hydrogen
bonding. In the first step, the electron density is transferred from the
oxygen lone electron pairs of the proton acceptor ((CH3)(2)O) to
fluorine lone electron pairs of the proton donor (CHF3) which yields
elongation of all CF bonds. Elongation of CF bonds is followed (in the
second step) by structural reorganization of the CHF3 moiety, which
leads to the contraction of the CH bond. It is thus clearly demonstrated
that not only the spectral manifestation of H-bonding and improper
H-bonding but also their nature differ.,
DOI = 10.1021/ja010915t,
ISSN = 0002-7863,
Unique-ID = ISI:000172645100020,
J. Sponer, J. Leszczynski, and P. Hobza, "Hydrogen bonding, stacking and cation binding of DNA bases," JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM, vol. 573, pp. 43-53, 2001.
[Bibtex]
@article ISI:000171670600005,
Author = Sponer, J and Leszczynski, J and Hobza, P,
Title = Hydrogen bonding, stacking and cation binding of DNA bases,
Journal = JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM,
Year = 2001,
Volume = 573,
Pages = 43-53,
Month = OCT 26,
Abstract = Ab initio, quantum chemical calculations with inclusion of electron
correlation effects significantly contributed to our understanding of
molecular interactions of DNA bases. Some of the most important findings
are introduced in the present overview: nonplanarity of nucleobases,
out-of-plane hydrogen bonds and amino acceptor interactions, structures
and energies of hydrogen bonded base pairs, nature of base stacking, and
interactions between metal cations and nucleobases. Also, accuracy of
density functional theory, semi-empirical methods, distributed multipole
analysis and empirical potentials is briefly commented on. (C) 2001
Elsevier Science B.V. All rights reserved.,
DOI = 10.1016/S0166-1280(01)00537-1,
ISSN = 0166-1280,
Unique-ID = ISI:000171670600005,
J. Munoz, J. Sponer, P. Hobza, M. Orozco, and F. Luque, "Interactions of hydrated Mg2+ cation with bases, base pairs, and
nucleotides. Electron topology, natural bond orbital, electrostatic, and
vibrational study," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 105, iss. 25, pp. 6051-6060, 2001.
[Bibtex]
@article ISI:000169534900029,
Author = Munoz, J and Sponer, J and Hobza, P and Orozco, M and Luque, FJ,
Title = Interactions of hydrated Mg2+ cation with bases, base pairs, and
nucleotides. Electron topology, natural bond orbital, electrostatic, and
vibrational study,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2001,
Volume = 105,
Number = 25,
Pages = 6051-6060,
Month = JUN 28,
Abstract = A theoretical investigation of the influence of divalent metal cation
binding on the nucleic base pairing is presented. The investigation
includes a variety of theoretical analyses, which include electron
topology properties, electrostatic properties, natural bond orbital
analysis, and harmonic vibrational analysis. All calculations reported
here involve pentahydrated Mg2+ cation interacting with the base pairs
GC, GG, and AU and their complexes formed by the corresponding purine
nucleotide. The present calculations provide an important
physicochemical insight into metal cation-base interactions.
Particularly, they allow us to explain the striking difference in the
cation-induced enhancement of base pairing observed in G-containing base
pairs compared to A-containing base pairs. Indeed, the results also
reveal the active role of hydrating water molecules in modulating the
binding of the cation through a specific network of hydrogen bonds with
both the purine and the phosphate group. The results can be valuable for
gaining further insight into the effect of metal cation binding to the
N7 site of guanine and adenine in physiological DNA.,
DOI = 10.1021/jp010486l,
ISSN = 1089-5647,
Unique-ID = ISI:000169534900029,
methylated nucleic acid base pairs: Molecular dynamics and quantum
chemical ab initio studies," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 105, iss. 24, pp. 5804-5817, 2001.
[Bibtex]
@article ISI:000169371500032,
Author = Kabelac, M and Hobza, P,
Title = Potential energy and free energy surfaces of all ten canonical and
methylated nucleic acid base pairs: Molecular dynamics and quantum
chemical ab initio studies,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2001,
Volume = 105,
Number = 24,
Pages = 5804-5817,
Month = JUN 21,
Abstract = The potential energy surfaces (PESs) and free energy surfaces (FESs) of
all 10 canonical and methylated nucleic acid base pairs were studied by
a molecular dynamics/quenching (MD/Q) technique with the Cornell et al.
empirical force field and by a correlated ab initio quantum chemical
method. More than a dozen energy minima were located on the PES of each
base pair. The global and first local minima of nonmethylated base pairs
have a systematically planar H-bonded structure, while T-shaped and
stacked structures are less stable. The MD/Q search sometimes reveals an
unexpected structure as the global energy minimum (e.g., the global
minimum of the adenine...thymine PES corresponds neither to the
Watson-Crick nor the Hoogsteen type of bonding). Entropy does not play
an important role and the relative order of individual structures on the
PES and FES does not differ too much. Methylation at purine N9 and
pyrimidine N1 brings dramatic changes in the PESs and FESs, mainly
because the most stable and most populated H-bonded structures are
eliminated. In the case of methylated base pairs entropy plays an
important role and the structure of the global minimum does not usually
correspond to the most populated structure: frequently, it is the
stacked structure which is the most populated. Theoretical calculations
reveal that the PESs and FESs of most base pairs are very complex and
are characterized by the coexistence of several structures, which makes
assignment of various experimental characteristics difficult or even
unfeasible. In the case of PESs, the only exceptions were
guanine...cytosine and guanine...guanine pairs and their methylated
analogues. The respective PESs contained one or two stable structures
while the other structures were significantly less stable. Further,
three pairs (cytosine...thymine, guanine...guanine, and
guanine...thymine) possessed simple FESs at 300 K, where one or two
structures were populated considerably motre than the others.,
ISSN = 1089-5647,
Unique-ID = ISI:000169371500032,
B. Reimann, K. Buchhold, S. Vaupel, B. Brutschy, Z. Havlas, V. Spirko, and P. Hobza, "Improper, blue-shifting hydrogen bond between fluorobenzene and
fluorobenzene," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 105, iss. 23, pp. 5560-5566, 2001.
[Bibtex]
@article ISI:000169371200008,
Author = Reimann, B and Buchhold, K and Vaupel, S and Brutschy, B and Havlas, Z
and Spirko, V and Hobza, P,
Title = Improper, blue-shifting hydrogen bond between fluorobenzene and
fluorobenzene,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2001,
Volume = 105,
Number = 23,
Pages = 5560-5566,
Month = JUN 14,
Abstract = Weakly-bonded 1:1 complexes between fluorobenzene
(Fb)/fluorobenzene-d(5) (Fb-d(5)) and fluoroform (Ff) were investigated
spectroscopically by infrared ion-depletion spectroscopy (IR/R2PI) and
theoretically by correlated ab initio methods. Their predissociation
spectra exhibit an absorption comprised of two superimposed bands. These
are blue-shifted by 12 and 21 cm(-1), respectively, relative to the CH
stretch of isolated fluoroform. Each IR band is assigned to a different
hydrogen-bonded fluorobenzene fluoroform isomer; The isomer with the
most blue-shifted CH stretching vibration (21 cm(-1)) is assigned to a
sandwich type structure, exhibiting a CH rt hydrogen bond. The cluster
structures have been calculated by counterpoise- (CP-) corrected
gradient optimization combined with anharmonic vibrational analysis
using the CP-corrected Hessians. The predicted blue-shifts are 21 and
20.5 cm(-1) for the CH stretching frequencies of fluoroform upon
formation of a sandwich and a planar structure, respectively. The
theoretical and experimental shifts are thus well comparable. Natural
bond orbital (NBO) analysis of the sandwich complex as well as analysis
of the type and shape of the occupied molecular orbitals revealed the
nature of the blue-shift. It is shown that the nature of the improper,
blue-shifting H-bond in this complex differs from that in a common
I-I-bond. While in the common XH . . .Y hydrogen bond the primary
interaction is caused by an electron density transfer (EDT) from the
electron donor Y to the antibonding orbitals of XH, leading to the
red-shift and bond elongation in XH, the features of the improper,
blue-shifting H-bond are due to secondary effects. In the sandwich
complex the EDT takes place between the electron donor (pi electron
clouds of fluorobenzene) and the lone pairs of the fluorine atoms of
fluoroform, leading to a structural reorganization of the fluoroform,
including the contraction of the CK,bond and a corresponding blue-shift
of its CH stretching frequency. The NBO analysis as well as the analysis
of the type and shape of the HOMO and HOMO-1 orbitals both elucidate the
larger blue-shift for the sandwich-type isomer of the fluorobenzene
fluoroform cluster compared to the equivalent chloroform complex.,
DOI = 10.1021/jp003726q,
ISSN = 1089-5639,
Unique-ID = ISI:000169371200008,
M. Kabelac and P. Hobza, "At nonzero temperatures, stacked structures of methylated nucleic acid
base pairs and microhydrated nonmethylated nucleic acid base pairs are
favored over planar hydrogen-bonded structures: A molecular dynamics
simulations study," CHEMISTRY-A EUROPEAN JOURNAL, vol. 7, iss. 10, pp. 2067-2074, 2001.
[Bibtex]
@article ISI:000168906800002,
Author = Kabelac, M and Hobza, P,
Title = At nonzero temperatures, stacked structures of methylated nucleic acid
base pairs and microhydrated nonmethylated nucleic acid base pairs are
favored over planar hydrogen-bonded structures: A molecular dynamics
simulations study,
Journal = CHEMISTRY-A EUROPEAN JOURNAL,
Year = 2001,
Volume = 7,
Number = 10,
Pages = 2067-2074,
Month = MAY 18,
Abstract = The dynamic structure of all ten possible nucleic acid (NA) base pairs
and methylated NA base pairs hydrated by a small number of water
molecules (from 1 to 16) was determined by using molecular dynamics
simulations in the NVE microcanonical and NVT canonical ensembles with
the Cornell force field (W. D. Cornell, P. Cieplak, C. I. Bayly, I.
R.Gould, K. M. Merz, D. M. Ferguson, D. C. Spellmeyer, T. Fox, J. E.
Caldwell, P. Kollman, J. Am. Chem. Sec. 1995, 117, 5179). The presence
of one water molecule does not affect the structure of any
hydrogen-bonded (H-bonded) nonmethylated base pair. An equal population
of H-bonded and stacked structures of adenine adenine, adenine guanine
and adenine thymine pairs is reached if as few as two water molecules
are present, while obtaining equal populations of these structures in
the case of adenine cytosine, cytosine thymine, guanine guanine and
guanine thymine required the presence of four water molecules, and in
the case of guanine cytosine, six. A comparable population of planar,
H-bonded and stacked structures for cytosine cytosine and thymine
thymine base pairs was only obtained if at least eight water molecules
hydrated a pair. Methylation of bases changed the situation dramatically
and stacked structures were favoured over H-bonded ones even in the
absence of water molecules in most cases. Only in the case of methyl
cytosine methyl cytosine, methyl guanine methyl guanine and methyl
guanine methyl cytosine pairs were two, two or six water molecules,
respectively, needed in order to obtain a comparable population of
planar, H-bonded and stacked structures. We believe that these results
give clear evidence that the preferred stacked structure of NA base
pairs in the microhydrated environment, and also apparently in a regular
solvent, is due to the hydrophilic interaction of a small number of
water molecules. In the case of methylated bases, it is also due to the
fact that the hydrogen atoms most suitable for the formation of H-bonds
have been replaced by a methyl group. A preferred stacked structure is,
thus, not due to a hydrophobic interaction between a large bulk of water
molecules and the base pair, as believed.,
DOI = 10.1002/1521-3765(20010518)7:10<2067::AID-CHEM2067>3.0.CO;2-S,
ISSN = 0947-6539,
Unique-ID = ISI:000168906800002,
M. Elstner, P. Hobza, T. Frauenheim, S. Suhai, and E. Kaxiras, "Hydrogen bonding and stacking interactions of nucleic acid base pairs: A
density-functional-theory based treatment," JOURNAL OF CHEMICAL PHYSICS, vol. 114, iss. 12, pp. 5149-5155, 2001.
[Bibtex]
@article ISI:000167401000007,
Author = Elstner, M and Hobza, P and Frauenheim, T and Suhai, S and Kaxiras, E,
Title = Hydrogen bonding and stacking interactions of nucleic acid base pairs: A
density-functional-theory based treatment,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 2001,
Volume = 114,
Number = 12,
Pages = 5149-5155,
Month = MAR 22,
Abstract = We extend an approximate density functional theory (DFT) method for the
description of long-range dispersive interactions which are normally
neglected by construction, irrespective of the correlation function
applied. An empirical formula, consisting of an R-6 term is introduced,
which is appropriately damped for short distances; the corresponding C-6
coefficient, which is calculated from experimental atomic
polarizabilities, can be consistently added to the total energy
expression of the method. We apply this approximate DFT plus dispersion
energy method to describe the hydrogen bonding and stacking interactions
of nucleic acid base pairs. Comparison to MP2/6-31G*(0.25) results
shows that the method is capable of reproducing hydrogen bonding as well
as the vertical and twist dependence of the interaction energy very
accurately. (C) 2001 American Institute of Physics.,
DOI = 10.1063/1.1329889,
ISSN = 0021-9606,
Unique-ID = ISI:000167401000007,
center dot center dot 1-methylthymine pair are populated equally at
experimental conditions: Ab initio and molecular dynamics study," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 105, iss. 7, pp. 1197-1202, 2001.
[Bibtex]
@article ISI:000167130400015,
Author = Ryjacek, F and Engkvist, O and Vacek, J and Kratochvil, M and Hobza, P,
Title = Hoogsteen and stacked structures of the 9-methyladenine center dot
center dot center dot 1-methylthymine pair are populated equally at
experimental conditions: Ab initio and molecular dynamics study,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2001,
Volume = 105,
Number = 7,
Pages = 1197-1202,
Month = FEB 22,
Abstract = The potential energy surface (PES) of the
9-methyladenine...1-methylthymine (mA...mT) nucleic acid base pair was
investigated using molecular dynamics/quenching method utilizing the
Cornell et al. (Cornell, W. D.; Cieplak, P.: Bayly, C. I.: Gould, I. R.,
Merz, K. M., Jr.; Ferguson, D. M.; Spellmeyer, D. C.; Fox, T.; Caldwell,
J. W.; Kollman, P. A. J. Am. Chem. Sec. 1995, 117, 5179) empirical force
field. Altogether 16 energy minima were found, 4 of them were planar,
hydrogen-bonded, and 9 stacked. The accuracy of the stabilization
energies evaluated with Cornell et al. empirical force field was
verified by comparing them with correlated ab initio stabilization
energies and good agreement was found for hydrogen-bonded as well as
stacked pairs. NVE and NVT free energy surfaces were estimated by means
of computer simulations. In the NVE simulations stacked structures
prevail, while in the NVT calculations an equal mixture of planar
hydrogen bonded reversed Hoogsteen and Hoogsteen structures, and two
stacked structures was found. The averaged stabilization enthalpy
considering all the dimer structures (NVT simulations) is ii kcal/mol
and agrees well with the experimental stabilization enthalpy for the
formation of mA mT pair (13 kcal/mol) obtained from field ionization
mass spectrometry measurements at conditions comparable to the NVT
simulations.,
ISSN = 1089-5639,
Unique-ID = ISI:000167130400015,
J. Sponer, J. Leszczynski, and P. Hobza, "Electronic properties, hydrogen bonding, stacking, and cation binding of
DNA and RNA bases," BIOPOLYMERS, vol. 61, iss. 1, pp. 3-31, 2001.
[Bibtex]
@article ISI:000174187300002,
Author = Sponer, J and Leszczynski, J and Hobza, P,
Title = Electronic properties, hydrogen bonding, stacking, and cation binding of
DNA and RNA bases,
Journal = BIOPOLYMERS,
Year = 2001,
Volume = 61,
Number = 1,
Pages = 3-31,
Abstract = This review summarizes results concerning molecular interactions of
nucleic acid bases as revealed by advanced ab initio quantum chemical
(QM) calculations published in last few years. We first explain
advantages and limitations of modem QM calculations of nucleobases and
provide a brief history of this still rather new field. Then we provide
an overview of key electronic properties of standard and selected
modified nucleobases, such as their charge distributions, dipole
moments, polarizabilities, proton affinities, tautomeric equilibria, and
amino group hybridization. Then we continue with hydrogen bonding of
nucleobases, by analyzing energetics of standard basepairs,yI mismatched
base pairs, thio-base pairs, and others. After this, the nature of
aromatic stacking interactions is explained. Also, nonclassical
interactions in nucleic acids such as interstrand bifurcated hydrogen
bonds, interstrand close amino group contacts, C-H... O interbase
contacts, sugars base stacking, intrinsically nonplanar base pairs,
out-of-plane hydrogen bonds, and amino-acceptor interactions are
commented on. Finally, we overview recent calculations on interactions
between nucleic acid bases and metal cations, These studies deal with
effects of cation binding on the strength of base pairs, analysis of
specific differences among cations, such as the difference between zinc
and magnesium, the influence of metalation on protonation and tautomeric
equlibria of bases, and cation-pi,T interactions involving nucleobases.
In this review, we do not provide methodological details, as these can
be found in our preceding reviews. The interrelation between advanced QM
approaches and classical molecular dynamics simulations is briefly
discussed. (C) 20021 Wiley Periodicals, Inc.,
DOI = 10.1002/1097-0282(2001)61:1<3::AID-BIP10048>3.0.CO;2-4,
ISSN = 0006-3525,
Unique-ID = ISI:000174187300002,
P. Hobza, "The H-index unambiguously discriminates between hydrogen bonding and
improper blue-shifting hydrogen bonding," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 3, iss. 13, pp. 2555-2556, 2001.
[Bibtex]
@article ISI:000169525300001,
Author = Hobza, P,
Title = The H-index unambiguously discriminates between hydrogen bonding and
improper blue-shifting hydrogen bonding,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2001,
Volume = 3,
Number = 13,
Pages = 2555-2556,
Abstract = X-H . . .Y contacts are characterised by a red shift of the X-H stretch
frequency. We have shown recently (P. Hobza and Z. Havlas, Chem. Rev.,
2000, 100, 4253) that these contacts can also be characterised by a blue
shift of the X-H stretch frequency. An H-index, defined as the ratio of
electron density transferred from the proton donor (Y) to the sigma*
antibonding orbital of the X-H bond and the total electron density
transferred between proton donor and proton acceptor unambiguously
discriminates between both types of H-bonding. Its value for proper
H-bonding lies between 1.0 and 0.7 while values between 0.3 and 0 are
typical for improper (blue-shifting) H-bonding.,
DOI = 10.1039/b103068j,
ISSN = 1463-9076,
Unique-ID = ISI:000169525300001,
study of H-bonded and stacked DNA base pairs," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 3, iss. 20, pp. 4578-4582, 2001.
[Bibtex]
@article ISI:000171711400018,
Author = Jurecka, P and Nachtigall, P and Hobza, P,
Title = RI-MP2 calculations with extended basis sets - a promising tool for
study of H-bonded and stacked DNA base pairs,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2001,
Volume = 3,
Number = 20,
Pages = 4578-4582,
Abstract = The interaction energies of 9-methyladenine . . .1-methylthymine
H-bonded and 9-methyladenine . . . 9-methylguanine stacked pairs were
evaluated at the MP2 and resolution of the identity MP2 (RI-MP2) levels.
The interaction energies are almost identical for both methods. The
RI-MP2 method is about one order of magnitude faster than the exact MP2
method and, therefore, this method is well suited for the study of large
models of biological importance. The basis set dependence of both base
pairs was studied and reasonable relative energy characteristics were
obtained only if at least the valence double-zeta -polarisation SVP
basis set with modified (diffuse) polarisation functions on non-hydrogen
and hydrogen atoms was used. However, reliable absolute stabilisation
energies of both base pairs were only obtained if at least the aug-SVP
basis set is applied. Stack interaction energies and three- and
four-body energy terms for selected base-pair steps of B-DNA were
calculated for the first time using the RI-MP2 method and the aug-SVP
basis set.,
ISSN = 1463-9076,
Unique-ID = ISI:000171711400018,
2000
O. Shishkin, L. Gorb, P. Hobza, and J. Leszczynski, "Structural nonrigidity of nucleic acid bases. Post-Hartree-Fock ab
initio study," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 80, iss. 4-5, pp. 1116-1124, 2000.
[Bibtex]
@article ISI:000165108300060,
Author = Shishkin, OV and Gorb, L and Hobza, P and Leszczynski, J,
Title = Structural nonrigidity of nucleic acid bases. Post-Hartree-Fock ab
initio study,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 2000,
Volume = 80,
Number = 4-5,
Pages = 1116-1124,
Month = NOV-DEC,
Note = 40th Annual Sanibel Symposium, ST AUGUSTINE, FL, FEB 26-MAR 03, 2000,
Organization = IBM Corp; HyperCube Inc; Univ Florida,
Abstract = Pyrimidine ring deformation modes in uracil, thymine, cytosine,
isocytosine, guanine, and adenine were analyzed using normal vibrations
calculated at the MP2/6-31G(d,p) levels of theory. We have introduced
the theoretical approach based on the combined analysis of the shape of
the relaxed potential surface, normal out-of-plane frequencies, and the
amplitudes of the corresponding vibrations. We have shown that the
absolute value of the frequency is not the unique characteristic to
determine the lowest modes of the molecular deformation. We have
revealed the applications involved in the analysis of the amplitudes to
locate the internal coordinates (torsional angels), which correspond to
the set of lowest energy deformations. It was demonstrated that the
pyrimidine ring possesses high structural nonrigidity. Two very soft
modes of ring deformation were found for every molecule except adenine.
An estimation of population of excited vibrational levels for the lowest
out-of-plane ring vibrations reveals that in every moment of time about
50\% of all considered molecules possess a nonplanar configuration in
the pyrimidine ring with a relevant torsion angle up to 25 degrees (C)
2000 John Wiley \& Sons, Inc.,
DOI = 10.1002/1097-461X(2000)80:4/5<1116::AID-QUA61>3.3.CO;2-F,
ISSN = 0020-7608,
Unique-ID = ISI:000165108300060,
B. Brutschy and P. Hobza, "van der Waals molecules III: Introduction," CHEMICAL REVIEWS, vol. 100, iss. 11, pp. 3861-3862, 2000.
[Bibtex]
@article ISI:000165415200001,
Author = Brutschy, B and Hobza, P,
Title = van der Waals molecules III: Introduction,
Journal = CHEMICAL REVIEWS,
Year = 2000,
Volume = 100,
Number = 11,
Pages = 3861-3862,
Month = NOV,
DOI = 10.1021/cr990074x,
ISSN = 0009-2665,
Unique-ID = ISI:000165415200001,
P. Hobza and Z. Havlas, "Blue-shifting hydrogen bonds," CHEMICAL REVIEWS, vol. 100, iss. 11, pp. 4253-4264, 2000.
[Bibtex]
@article ISI:000165415200016,
Author = Hobza, P and Havlas, Z,
Title = Blue-shifting hydrogen bonds,
Journal = CHEMICAL REVIEWS,
Year = 2000,
Volume = 100,
Number = 11,
Pages = 4253-4264,
Month = NOV,
DOI = 10.1021/cr990050q,
ISSN = 0009-2665,
Unique-ID = ISI:000165415200016,
theoretical study," JOURNAL OF CHEMICAL PHYSICS, vol. 113, iss. 11, pp. 4629-4635, 2000.
[Bibtex]
@article ISI:000089139900017,
Author = Bludsky, O and Chocholousova, J and Vacek, J and Huisken, F and Hobza, P,
Title = Anharmonic treatment of the lowest-energy conformers of glycine: A
theoretical study,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 2000,
Volume = 113,
Number = 11,
Pages = 4629-4635,
Month = SEP 15,
Abstract = The structure and energetics of the four lowest-energy conformers of
glycine were determined at the MP2/aug-cc-pVDZ level of theory. The
optimized structural parameters for these conformers agree with previous
theoretical results obtained by highly correlated ab initio methods and
with available experimental data. The only structure with planar heavy
atom arrangement is conformer I (global minimum), the other conformers
have nonplanar heavy atom arrangements. In accordance with temperature
dependence studies of the vibrational spectra in various rare gas
environments, conformers III and IV have small interconversion barriers
to conformer I (940 and 740 cm-(1)). Our calculations have shown that
full-dimensional anharmonic treatment is required for an accurate
description of the vibrational modes in various glycine conformers. The
most pronounced effect has been observed for conformer II with the
intramolecular O-H ... N bond. The theoretical results obtained at the
MP2/aug-cc-pVDZ level reproduce quantitatively the argon matrix
experiments. The calculation uses the quartic force field approximation
in the framework of second-order perturbation theory. An estimate of the
higher-order correction is also given. (C) 2000 American Institute of
Physics. [S0021-9606(00)30335-X].,
ISSN = 0021-9606,
Unique-ID = ISI:000089139900017,
J. Sponer, M. Sabat, L. Gorb, J. Leszczynski, B. Lippert, and P. Hobza, "The effect of metal binding to the N7 site of purine nucleotides on
their structure, energy, and involvement in base pairing," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 104, iss. 31, pp. 7535-7544, 2000.
[Bibtex]
@article ISI:000088683700044,
Author = Sponer, J and Sabat, M and Gorb, L and Leszczynski, J and Lippert, B and
Hobza, P,
Title = The effect of metal binding to the N7 site of purine nucleotides on
their structure, energy, and involvement in base pairing,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2000,
Volume = 104,
Number = 31,
Pages = 7535-7544,
Month = AUG 10,
Abstract = Direct binding of hydrated zinc and magnesium group divalent cations to
the N7 position of purine nucleotides has been investigated by ab initio
quantum chemical calculations. The sugar-phosphate backbone provides
significant screening of the charge of the metal while the backbone
geometry can be affected by the cation, Polarized water molecules of the
cation hydration shell form very strong hydrogen bond bridges between
the cation and the anionic oxygen atoms of the phosphate group, Weaker
hydrogen bonds are formed between the cation hydration shell and the
exocyclic purine X6 atoms. The cation binding to N7 of adenosine
monophosphate forces the adenine amino group to be nonplanar, Its
nitrogen atom serves as an H-acceptor for a water molecule from the
cation hydration shell while the amino-group hydrogen atom adjacent to
N7 sharply deviates from the adenine plane. This hydrogen is capable of
forming out-of-plane hydrogen bonds with a neighboring base pair or a
water molecule in DNA, Cation binding to N7 does not lead to any major
changes in the geometry of the base pairing, However, the stability of
the base pairing can be increased by polarization of the purine base by
the cation and by long-range electrostatic attraction between the
hydrated cation and the other nucleobase. The stability of
guanine-cytosine Watson-Crick base pairing is enhanced by the
polarization mechanism while the stability of the adenine-thymine
Watson-Crick base pair is enhanced by the electrostatic effects. The
guanine-guanine reverse-Hoogsteen base pairing is stabilized by both
contributions while the adenine-adenine reverse-Hodgsteen system is not
influenced by the cation. Binding of a cation to the N7 of guanine
promotes transfer of its H1 proton to the N3 acceptor site of cytosine.
However, the negatively charged backbone exerts a significant screening
effect on this potentially mutagenic process, and the probability of
such a proton transfer in DNA should be only moderately enhanced by a
cation binding, The complexes studied are characterized by highly
nonadditive molecular interactions. This implies limited applicability
of pair additive potentials to describe the direct binding of divalent
cations to nucleobases in DNA.,
DOI = 10.1021/jp001711m,
ISSN = 1089-5647,
Unique-ID = ISI:000088683700044,
P. Hobza, J. Sponer, E. Cubero, M. Orozco, and F. Luque, "C-H center dot center dot center dot O contacts in the adenine center
dot center dot center dot uracil Watson-Crick and uracil center dot
center dot center dot uracil nucleic acid base pairs: Nonempirical ab
initio study with inclusion of electron correlation effects," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 104, iss. 26, pp. 6286-6292, 2000.
[Bibtex]
@article ISI:000088057100028,
Author = Hobza, P and Sponer, J and Cubero, E and Orozco, M and Luque, FJ,
Title = C-H center dot center dot center dot O contacts in the adenine center
dot center dot center dot uracil Watson-Crick and uracil center dot
center dot center dot uracil nucleic acid base pairs: Nonempirical ab
initio study with inclusion of electron correlation effects,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 2000,
Volume = 104,
Number = 26,
Pages = 6286-6292,
Month = JUL 6,
Abstract = Structures and stabilities of H-bonded adenine ... uracil Watson-Crick
(AU WC) and two uracil ... uracil nucleic acid base pairs possessing C-H
... O contacts (UU7, UU-C) were determined using gradient optimization
with inclusion of electron correlation via the second-order
Moller-Plesset (MP2) perturbational method with a 6-31G** basis set
of atomic orbitals. In the AU WC pair, closest contacts occur between
the N6(A) and O4(U), N1(A) and N3(U), and C2(TL)and O2(U) atoms: 2.969,
2.836, and 3.568 Angstrom, respectively. For the UU7 pair the closest
contact corresponds to O4 ... N1 and C5 ... O2 pairs with distances of
2.860 and 3.257 Angstrom, respectively, while in UU-C pair the closest
contact was found Tor O4 ... N3 and C5 ... O4 heteroatoms with distances
of 2.913 and 3.236 Angstrom, respectively. The nature of all
intermolecular contacts in the sense of a conventional H-bonding or
improper, blue-shifting H-bonding was determined on the basis of
harmonic vibrational analysis, atom-in-molecules (AIM) Bader analysis of
electron density, and natural bond orbital analysis (NBO) performed at
the MP2/6-31G** level of theory. N-H stretch Frequencies of A and U
exhibited a red shift and intensity decrease upon formation of AU WC
base pair, it unambiguously proves the existence of the N-H ... O and O
... H-N H-bonds. The frequency shift of the C-H stretching frequency of
A upon complex formation is, however, marginal (similar to 2 cm(-1)).
Bader AIM analysis and NBO analysis confirmed the existence of N-H ... O
and O ... H-N H-bonds in the AU WC pair but was inconclusive in the case
of C-H ... O contact. The results thus clearly show that the C2-H2 ...
O2 contact in the AU or AT WC base pair corresponds neither to standard
H-bond nor to improper, blue-shifting H-bond. The opposite result,
however, has been found for the UU pairs; here the vibrational analysis
shows a red shift and intensity increase of both N-H and C-H stretching
vibrational frequencies upon the formation of the pair. This is a clear
manifestation of the presence of two H-bonds of the N-H ... O and O ...
H-C types. Bader AIM analysis as well as NBO analysis confirmed the
existence of both H-bonds.,
DOI = 10.1021/jp0007134,
ISSN = 1089-5647,
Unique-ID = ISI:000088057100028,
F. Lankas, J. Sponer, P. Hobza, and J. Langowski, "Sequence-dependent elastic properties of DNA," JOURNAL OF MOLECULAR BIOLOGY, vol. 299, iss. 3, pp. 695-709, 2000.
[Bibtex]
@article ISI:000087540100012,
Author = Lankas, F and Sponer, J and Hobza, P and Langowski, J,
Title = Sequence-dependent elastic properties of DNA,
Journal = JOURNAL OF MOLECULAR BIOLOGY,
Year = 2000,
Volume = 299,
Number = 3,
Pages = 695-709,
Month = JUN 9,
Abstract = Harmonic elastic constants of 3-11 bp duplex DNA fragments were
evaluated using four 5 ns unrestrained molecular dynamics simulation
trajectories of 17 bp duplexes with explicit inclusion of solvent and
counterions. All simulations were carried out with the Cornell cf nl.
force-field and particle mesh Ewald method for long-range electrostatic
interactions. The elastic constants including anisotropic bending and
all coupling terms were derived by analyzing the correlations of
fluctuations of structural properties along the trajectories. The
following sequences have been considered: homopolymer d(ApA)(n) and
d(GpG)(n), and alternating d(GPC)(n), and d(APT)(n),. The calculated
values of Elastic constants are in very good overall agreement with
experimental values for random sequences. The atomic-resolution
molecular dynamics approach, however, reveals a pronounced
sequence-dependence of the stretching and torsional rigidity of DNA,
while sequence-dependence of the bending rigidity is smaller for the
sequences considered. The earlier predicted twist-bend coupling emerged
as the most important cross-term for fragments shorter than one helical
turn. The calculated hydrodynamic relaxation times suggest that damping
of bending motions mag: play a role in molecular dynamics simulations of
long DNA fragments. A comparison of elasticity calculations using global
and local helicoidal analyses is reported, The calculations reveal the
importance of the fragment length definition. The present work shows
that large-scale molecular dynamics simulations represent a unique
source of data to study various aspects of DNA elasticity including its
sequence-dependence. (C) 2000 Academic Press.,
DOI = 10.1006/jmbi.2000.3781,
ISSN = 0022-2836,
Unique-ID = ISI:000087540100012,
base pairs, nucleoside pairs, nucleotide pairs and B-DNA pairs of
trinucleotides: ab initio HF/MINI-1 and empirical force field study," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 17, iss. 6, pp. 1077-1086, 2000.
[Bibtex]
@article ISI:000088443900014,
Author = Kabelac, M and Kratochvil, M and Sponer, J and Hobza, P,
Title = Structure, energetics, vibrational frequencies and charge transfer of
base pairs, nucleoside pairs, nucleotide pairs and B-DNA pairs of
trinucleotides: ab initio HF/MINI-1 and empirical force field study,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 2000,
Volume = 17,
Number = 6,
Pages = 1077-1086,
Month = JUN,
Abstract = Geometries, interaction energies and vibrational frequencies of base
pairs, nucleoside pairs and nucleotide pairs were studied by ab initio
Hartree-Fock (HF) method using MINI-1 basis set and empirical Cornell ee
al. force field (AMBER 4.1). A good agreement was found between
HF/MINI-1 and AMBER results. In addition, both methods provide
reasonable agreement with available high-level ab initio data. Finally,
AMBER potential was used to determine the structure, energetics and
vibrational frequencies of B-DNA pairs of trinucleotides. Stabilization
energies of clusters are lowered when passing from base pairs to
nucleoside pairs, nucleotide pairs and to pairs of trinucleotides. The
lowest vibrations of base pairs and nucleoside pairs correspond to
intermolecular motions of bases, specifically to buckle and propeller
motions. In the case of pairs of larger subunits the lowest vibrations
are of intramolecular nature (rotation around glycosidic bond, sugar and
phosphate vibration). The spectra of these clusters became more
complicated and quasi-degenerate. Intermolecular charge transfer between
bases in H-bonded and stacked pairs is negligible, while a significant
intramolecular charge transfer was observed.,
ISSN = 0739-1102,
Unique-ID = ISI:000088443900014,
J. Sponer and P. Hobza, "Interaction energies of hydrogen-bonded formamide dimer, formamidine
dimer, and selected DNA base pairs obtained with large basis sets of
atomic orbitals," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 104, iss. 19, pp. 4592-4597, 2000.
[Bibtex]
@article ISI:000087003200032,
Author = Sponer, J and Hobza, P,
Title = Interaction energies of hydrogen-bonded formamide dimer, formamidine
dimer, and selected DNA base pairs obtained with large basis sets of
atomic orbitals,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 2000,
Volume = 104,
Number = 19,
Pages = 4592-4597,
Month = MAY 18,
Abstract = Interaction energies of selected H-bonded nucleic acids base pairs,
formamide dimer, and formamidine dimer have been evaluated using the
second-order Moller-Plesset method (MP2) with extended basis sets of
atomic orbitals. Basis sets with two sets of d-polarization functions on
each non-hydrogen atom give the same interaction energies as
medium-sized 6-31G** and 6-31G*(0.25) basis sets. This is due to a
compensation of errors in the evaluation of the Hartree-Fock and
correlation interaction energies. With a further increase of the size of
the basis set, a steep improvement (increase in absolute value) of the
interaction energy appears. It amounts to 0.6-1.1 kcal/mol with the
cc-pVTZ basis set. The aug-cc-pVQZ. and cc-pV5Z, basis sets improve the
interaction energy of model complexes by additional ca. 1.3 kcal/mol
while these data appear to be very close to the basis set limit. In
contrast to the MP2 method, Becke3LYP density functional theory method
does not show any systematic improvement of the interaction energies
with the increase of the basis set size. The previously published
reference values for interaction energies of H-bonded base pairs
obtained with medium-sized basis sets of atomic orbitals are likely to
be underestimated tin absolute value) by 2.0-2.5 kcal/mol while relative
stabilities of base pairs are correctly reproduced. Nevertheless, with
the present computer facilities we cannot yet investigate in detail the
influence of the quality of the optimized geometries of the dimers on
their stabilization energies. It is expected, however, that this
contribution is considerably smaller compared to the primary basis set
enters evaluated in this study.,
DOI = 10.1021/jp9943880,
ISSN = 1089-5639,
Unique-ID = ISI:000087003200032,
M. Kratochvil, J. Sponer, and P. Hobza, "Global minimum of the adenine center dot center dot center dot thymine
base pair corresponds neither to Watson-Crick nor to Hoogsteen
structures. Molecular dynamic/quenching/AMBER and ab initio beyond
Hartree-Fock studies," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 122, iss. 14, pp. 3495-3499, 2000.
[Bibtex]
@article ISI:000086477100028,
Author = Kratochvil, M and Sponer, J and Hobza, P,
Title = Global minimum of the adenine center dot center dot center dot thymine
base pair corresponds neither to Watson-Crick nor to Hoogsteen
structures. Molecular dynamic/quenching/AMBER and ab initio beyond
Hartree-Fock studies,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 2000,
Volume = 122,
Number = 14,
Pages = 3495-3499,
Month = APR 12,
Abstract = Computational analysis of complete gas-phase potential energy and free
energy surfaces of the adenine thymine base pair has been carried out.
The study utilizes a combination of molecular dynamics simulations
performed with Cornell et al. empirical force field and quenching
technique. Twenty seven energy minima have been located at the potential
energy surface of the adenine thymine base pair: nine of them are
H-bonded structures, eight are T-shaped dimers, and the remaining nine
correspond to various stacked arrangements. H-bonded structures are the
most stable while stacked and T-shaped structures are by more than 4
kcal/mol less stable than the global minimum, The global minimum and the
first;two local minima utilize N(9)-H and N(3) groups of adenine for the
binding, i.e., the amino group N(6), and ring N(1) and N(7) adenine
positions are not involved in the base pairing. The most stable
H-bonding patterns cannot occur in nucleic acids since the Ns position
is blocked by the attached sugar ring. Hoogsteen and Watson-Crick type
structures (third and fourth local minima) are by about 3 kcal/mol less
stable than the global minimum. Energetic preferences of the global
minimum and first two local minima were confirmed by correlated MP2 ab
initio calculations with 6-31G** and -6-311G(2d,p) basis sets.
Relative population of various structures (a quantity proportional to
Delta G of base pair formation) was determined by molecular dynamics
simulations in the NVE microcanonical ensemble. Although the stability
order of the global and first two local minima is unaffected by
including the entropy contribution, the stability order of the remaining
structures is altered rather significantly in favor of stacked and
T-shaped structures. The simulations further show that the population of
the global minimum is about 35\% and it means that experimental
gas-phase studies are likely to detect a vast number of mutually
coexisting structures.,
DOI = 10.1021/ja9936060,
ISSN = 0002-7863,
Unique-ID = ISI:000086477100028,
M. Kratochvil, O. Engkvist, J. Vacek, P. Jungwirth, and P. Hobza, "Methylated uracil dimers: potential energy and free energy surfaces," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 2, iss. 10, pp. 2419-2424, 2000.
[Bibtex]
@article ISI:000086928000051,
Author = Kratochvil, M and Engkvist, O and Vacek, J and Jungwirth, P and Hobza, P,
Title = Methylated uracil dimers: potential energy and free energy surfaces,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2000,
Volume = 2,
Number = 10,
Pages = 2419-2424,
Abstract = Theoretical analysis of the formation of 1-methyluracil, 3-methyluracil
and 1,3-dimethyluracil dimers was performed. Stabilization energies of
these dimers were evaluated with the Cornell et al. force field (J. Am.
Chem. Soc., 1995, 117, 5179). In total 16, 13 and 15 energy minima were
studied for the three dimers. Thermodynamic data were obtained with the
rigid rotor-harmonic oscillator-ideal gas approximation. Furthermore,
populations of various structures were determined by molecular dynamic
simulations in the NVE microcanonical ensemble and numerical evaluation
of the configuration integrals in the NVT canonical ensemble. The
potential energy surfaces (PESs) and the free energy surfaces (FESs) of
these dimers differ. The largest difference was found for the
1-methyluracil dimer where the global and first local minima on the PES
and FES do not coincide.,
DOI = 10.1039/b001022g,
ISSN = 1463-9076,
Unique-ID = ISI:000086928000051,
M. Kabelac, F. Ryjacek, and P. Hobza, "Already two water molecules change planar H-bonded structures of the
adenine center dot center dot center dot thymine base pair to the
stacked ones: a molecular dynamics simulations study," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 2, iss. 21, pp. 4906-4909, 2000.
[Bibtex]
@article ISI:000165154300013,
Author = Kabelac, M and Ryjacek, F and Hobza, P,
Title = Already two water molecules change planar H-bonded structures of the
adenine center dot center dot center dot thymine base pair to the
stacked ones: a molecular dynamics simulations study,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 2000,
Volume = 2,
Number = 21,
Pages = 4906-4909,
Abstract = The dynamical structure of the adenine...thymine nucleic acid base pair
exposed to a small number of water molecules (from 1 to 216) was
determined using molecular dynamics simulations with Cornell et al.
force field (W. D. Cornell, P. Cieplak, C. I. Bayly, I. R.Gould, K. M.
Merz, D. M. Ferguson, D. C. Spellmeyer, T. Fox, J. E. Caldwell and P.
Kollman, J. Am. Chem. Soc., 1995, 117, 5179). The gradual increase of
hydration number results in a transition from planar base pair
structures to nonplanar ones, and already for two water molecules the
population of stacked structures is higher than that of planar
structures.,
DOI = 10.1039/b007167f,
ISSN = 1463-9076,
Unique-ID = ISI:000165154300013,
K. Muller-Dethlefs and P. Hobza, "Noncovalent interactions: A challenge for experiment and theory," CHEMICAL REVIEWS, vol. 100, iss. 1, pp. 143-167, 2000.
[Bibtex]
@article ISI:000085235400009,
Author = Muller-Dethlefs, K and Hobza, P,
Title = Noncovalent interactions: A challenge for experiment and theory,
Journal = CHEMICAL REVIEWS,
Year = 2000,
Volume = 100,
Number = 1,
Pages = 143-167,
Month = JAN,
DOI = 10.1021/cr9900331,
ISSN = 0009-2665,
Unique-ID = ISI:000085235400009,
dynamics simulations," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, iss. S2, pp. 383-407, 2000.
[Bibtex]
@article ISI:000165410200027,
Author = Sponer, J and Berger, I and Spackova, N and Leszczynski, J and Hobza, P,
Title = Aromatic base stacking in DNA: From ab initio calculations to molecular
dynamics simulations,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 2000,
Number = S2,
Pages = 383-407,
Note = 11th Conversation in Biomolecular Stereodynamics, SUNY ALBANY, ALBANY,
NY, JUN 15-19, 1999,
Organization = SUNY Albany, Dept Chem; SUNY Albany, Inst Biomolec Stereodynam,
Abstract = Aromatic stacking of nucleic acid bases is one of the key players in
determining the structure and dynamics of nucleic acids. The arrangement
of nucleic acid bases with extensive overlap of their aromatic rings
gave rise to numerous often contradictory suggestions about the physical
origins of stacking and the possible role of delocalized electrons in
stacked aromatic pi. systems, leading to some confusion about the issue.
The recent advance of computer hardware and software finally allowed the
application of state of the art quantum-mechanical approaches with
inclusion of electron correlation effects to study aromatic base
stacking, now providing an ultimitate qualitative description of the
phenomenon. Base stacking is determined by an interplay of the three
most commonly encountered molecular interactions: dispersion attraction,
electrostatic interaction, and short-range repulsion. Unusual
(aromatic-stacking specific) energy contributions were in fact not
evidenced and are not necessary to describe stacking. The currently used
simple empirical potential form, relying on atom-centered constant point
charges and Lennard-Jones van der Waals; terms, is entirely able to
reproduce the essential features of base stacking. Thus, we can conclude
that base stacking is in principle one of the best described
interactions in current molecular modeling and it allows to study base
stacking in DNA using large-scale classical molecular dynamics
simulations. Neglect of cooperativity of stacking appears to be the most
serious approximation of the currently used force field form.
This review summarizes recent developments in the field. It is written
for an audience that is not necessarily expert in computational quantum
chemistry and follows up on our previous contribution (Sponer et. al.,
J. Biomol. Struct. Dyn. 14, 117, (1996)). First, the applied
methodology, its accuracy, and the physical nature of base stacking is
briefly overviewed, including a comment on the accuracy of other
molecular orbital methods and force fields. Then, base stacking is
contrasted with hydrogen bonding, the other dominant force in nucleic
acid structure. The sequence dependence and cooperativity of base
stacking is commented on, and finally a brief introduction into recent
progress in large-scale molecular dynamics simulations of nucleic acids
is provided. Using four stranded DNA assemblies as an example, we
demonstrate the efficacy of current molecular dynamics techniques that
utilize refined and verified force fields in the study of stacking in
nucleic acid molecules.,
ISSN = 0739-1102,
Unique-ID = ISI:000165410200027,
1999
F. Ryjacek, M. Kratochvil, and P. Hobza, "Adenine... 2,4-difluorotoluene (modified base) pair: potential and
free-energy surfaces - Non-empirical and empirical potential studies," CHEMICAL PHYSICS LETTERS, vol. 313, iss. 1-2, pp. 393-398, 1999.
[Bibtex]
@article ISI:000083723800058,
Author = Ryjacek, F and Kratochvil, M and Hobza, P,
Title = Adenine... 2,4-difluorotoluene (modified base) pair: potential and
free-energy surfaces - Non-empirical and empirical potential studies,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1999,
Volume = 313,
Number = 1-2,
Pages = 393-398,
Month = NOV 5,
Abstract = Ab initio calculations are described for bonded and stacked structures
of adenine ... 2,4-difluorotoluene, Stabilization energies are
determined with inclusion of correlation energy at the MP2/6-31G *
(0.25) level. Stacked structures of the pair are more stable than planar
ones. The nucleic acid force field of Cornell et al. reproduces ab
initio stabilization energies of planar and stacked structures well. The
population of various structures of the pair, which is proportional to
Delta G of base pair formation, was determined by long runs of molecular
dynamics with the force field of Cornell et al. Potential- and
foe-energy surfaces are similar and, among 11 of the most populated
dimer structures, there is no planar H-bonded structure. (C) 1999
Elsevier Science B.V. All rights reserved.,
DOI = 10.1016/S0009-2614(99)01013-1,
ISSN = 0009-2614,
Unique-ID = ISI:000083723800058,
P. Hobza and J. Sponer, "Structure, energetics, and dynamics of the nucleic acid base pairs:
Nonempirical ab initio calculations," CHEMICAL REVIEWS, vol. 99, iss. 11, pp. 3247-3276, 1999.
[Bibtex]
@article ISI:000083794800004,
Author = Hobza, P and Sponer, J,
Title = Structure, energetics, and dynamics of the nucleic acid base pairs:
Nonempirical ab initio calculations,
Journal = CHEMICAL REVIEWS,
Year = 1999,
Volume = 99,
Number = 11,
Pages = 3247-3276,
Month = NOV,
DOI = 10.1021/cr9800255,
ISSN = 0009-2665,
Unique-ID = ISI:000083794800004,
J. Sponer, M. Sabat, J. Burda, J. Leszczynski, P. Hobza, and B. Lippert, "Metal ions in non-complementary DNA base pairs: an ab initio study of
Cu(I), Ag(I), and Au(I) complexes with the cytosine-adenine base pair," JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY, vol. 4, iss. 5, pp. 537-545, 1999.
[Bibtex]
@article ISI:000083283600003,
Author = Sponer, J and Sabat, M and Burda, JV and Leszczynski, J and Hobza, P and
Lippert, B,
Title = Metal ions in non-complementary DNA base pairs: an ab initio study of
Cu(I), Ag(I), and Au(I) complexes with the cytosine-adenine base pair,
Journal = JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY,
Year = 1999,
Volume = 4,
Number = 5,
Pages = 537-545,
Month = OCT,
Abstract = Ab initio calculations have been carried out to characterize the
structure and energetics of a silver(I) complex with the
cytosine-adenine DNA base pair and an aqua ligand in the coordination
sphere of Ag. In addition, we have also studied analogous complexes with
Cu(I) and Au(I), and structures in which adenine has been replaced by
purine in order to investigate the structural role of the adenine amino
group. The calculations revealed that all metal-modified structures are
dominated by the metal-base interactions, while the water-metal ion
interaction and many-body interligand repulsion are less important
contributions. Nevertheless, the structural role of the water molecule
in the complex is quite apparent and in agreement with an earlier
crystallographic study. The metal-modified base pairs exhibit large
conformational flexibility toward out-of-plane motions (propeller twist
and buckle), comparable or, in some cases, even larger than that
observed in the base pairs without metal ions. All structures have been
optimized within the Hartree-Fock approximation, while interaction
energies were evaluated with the inclusion of electron correlation.,
DOI = 10.1007/s007750050376,
ISSN = 0949-8257,
Unique-ID = ISI:000083283600003,
E. Cubero, M. Orozco, P. Hobza, and F. Luque, "Hydrogen bond versus anti-hydrogen bond: A comparative analysis based on
the electron density topology," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 103, iss. 32, pp. 6394-6401, 1999.
[Bibtex]
@article ISI:000082111400016,
Author = Cubero, E and Orozco, M and Hobza, P and Luque, FJ,
Title = Hydrogen bond versus anti-hydrogen bond: A comparative analysis based on
the electron density topology,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 1999,
Volume = 103,
Number = 32,
Pages = 6394-6401,
Month = AUG 12,
Abstract = The theory of atoms in molecules is used to examine the nature of
anti-hydrogen bond (anti-H bond) interaction. Contrary to what is found
in normal hydrogen bond (H bond) complexes, which are characterized by
lengthening of the X-H bond and a red shift of its stretching frequency,
the anti-H bond leads to a shortening of the X-H bond length and a blue
shift of its vibrational frequency. The topological properties of the
electron density have been determined for a series of C-H ...pi
complexes, which exhibit either anti-H bond or normal H bond character,
as well as for the complexes C(6)H(5)F ... HCCl(3) and C(6)H(6)... HF,
which are representative cases of anti- and normal H bonds. Inspection
of the set of topological criteria utilized to characterize conventional
H bonds shows no relevant difference in the two classes of H ...pi
complexes. Analysis of the results suggests that the specific features
of the anti-H bond originates from the redistribution of electron
density in the C-H bond induced upon complexation, which in turn
evidences the different response dispersion versus electrostatic- of the
interacting monomer for stabilizing the complex.,
DOI = 10.1021/jp990258f,
ISSN = 1089-5639,
Unique-ID = ISI:000082111400016,
thioguanine-cytosine DNA base pair: Ab initio and density functional
theory investigation of polarization effects, differences among cations,
and flexibility of the cation hydration shell," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 17, iss. 1, pp. 61-77, 1999.
[Bibtex]
@article ISI:000082511200006,
Author = Sponer, J and Burda, JV and Leszczynski, J and Hobza, P,
Title = Interactions of hydrated IIa and IIb group metal cations with
thioguanine-cytosine DNA base pair: Ab initio and density functional
theory investigation of polarization effects, differences among cations,
and flexibility of the cation hydration shell,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1999,
Volume = 17,
Number = 1,
Pages = 61-77,
Month = AUG,
Abstract = The structures and energies of the thioguanine-cytosine Watson-Crick
(thioGC WC) base pair interacting with hydrated IIa (Mg2+, Ca2+, Ba2+)
and IIb group (Zn2+, Cd2+ , Hg2+) cations have been studied using ab
initio techniques. Furthermore, complexes between guanine and
thioguanine with hydrated cations have been characterized assuming
various structures of the hydration shells. The complexes of the thioGC
WC base pair with hydrated cations have similar properties as the
previously studied GC WC base pair. There is substantial polarization
stabilization of the base pairing due to cation binding which amounts to
7 - 11 kcal/mol. Soft Cd2+ and Hg2+ cations have a uniquely strong
interaction with the thiogroup and induce substantial nonplanarity of
the pairing. The thiogroup tends to reduce the number of water molecules
in the first hydration shell of the cation. All complexes were optimized
within the Hartree-Fock (HE) approximation while their energetics has
been evaluated using the second-order Moller-Plesset perturbational
method (MP2). All interaction energy evaluations and a substantial
portion of the optimizations of the hydrated cation-(thio)guanine
complexes have been repeated using Becke-3LYP Density Functional Theory
method. All three approximations used (HE Becke-3LYP, and MP2) give
qualitatively the same results for the present cationic complexes. The
results demonstrate specific differences among the cations and provide a
set of reference structures and energies for verification and/or
parametrization of empirical potentials and other theoretical methods.,
ISSN = 0739-1102,
Unique-ID = ISI:000082511200006,
[Bibtex]
@article ISI:000081067300019,
Author = Spirko, V and Engvist, O and Soldan, P and Selzle, HL and Schlag, EW and
Hobza, P,
Title = Structure and vibrational dynamics of the benzene dimer,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1999,
Volume = 111,
Number = 2,
Pages = 572-582,
Month = JUL 8,
Abstract = Point-wise evaluated coupled-cluster single double triple [CCSD(T)]
stabilization energies are used to parameterize the nonempirical model
(NEMO) empirical intermolecular potential of the benzene dimer in the
ground electronic state. The potential is used for theoretical
interpretation of the dimer structure and the dynamics of its
intermolecular motions. Only one energy minimum, corresponding to the
T-shaped structure, is found. A parallel displaced structure is the
first-order transition structure separating the molecular symmetrically
equivalent T-shaped structures. Due to a relatively high transition
barrier (similar to 170 cm(-1)), the interconversion tunneling is
unimportant in the energy region spanned by the available rotational
spectra and is thus neglected (accordingly, the molecular symmetry group
which is used for interpretation of the available experimental spectra
is related to the T-shaped structure with two feasible internal
rotations and nonequivalent monomers). The dimer undergoes a nearly free
internal rotation along the axis connecting the benzene centers of mass
in the T-shaped equilibrium geometry and a hindered internal rotation
(the barrier being similar to 46 cm(-1)) along the axis that is
perpendicular to the ``nearly free'' internal rotation axis. The
tunneling splittings observed in the rotational spectrum are likely due
to this hindered rotation. An analysis assuming the latter rotation as
an independent motion and using purely vibrational tunneling splittings
(obtained by extrapolating to zero values of the rotational quantum
numbers) indicates that the genuine value of the hindered rotation
barrier is nearly twice higher than its ab initio value. Similarly, the
difference Delta R=0.25 Angstrom between the ab initio (equilibrium) and
experimental (ground state) values for the distance of the mass centers
of the benzene monomers is strong evidence that our theoretical
potential is much shallower than the genuine one. The Raman bands
observed at the 3-10 cm(-1) region seem to involve states associated
with the nearly free rotation and the ``energy minimum path'' bending
motion. Unambiguous assigning of the weaker Raman features is
infeasible, partly due to limitations in the accuracy of the theoretical
potential, and partly due to the lack of knowledge of the polarizability
tensor of the dimer and temperature at which the spectra were taken. (C)
1999 American Institute of Physics. [S0021-9606(99)00526-7].,
ISSN = 0021-9606,
Unique-ID = ISI:000081067300019,
P. Hobza, O. Bludsky, and S. Suhai, "Reliable theoretical treatment of molecular clusters:
Counterpoise-corrected potential energy surface and anharmonic
vibrational frequencies of the water dimer," PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 1, iss. 13, pp. 3073-3078, 1999.
[Bibtex]
@article ISI:000081545200003,
Author = Hobza, P and Bludsky, O and Suhai, S,
Title = Reliable theoretical treatment of molecular clusters:
Counterpoise-corrected potential energy surface and anharmonic
vibrational frequencies of the water dimer,
Journal = PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 1999,
Volume = 1,
Number = 13,
Pages = 3073-3078,
Month = JUL 1,
Abstract = Structure, properties and energetics of the water dimer were determined
by counterpoise (CP)-corrected gradient optimization which a priori
eliminates the basis set superposition error (BSSE). Calculations were
carried out at the MP2 level with various basis sets up to the
aug-cc-pVQZ one. Besides harmonic vibrational frequencies
twelve-dimensional anharmonic frequencies were also determined using the
second-order perturbation treatment. Harmonic and anharmonic frequencies
were based on CP-corrected Hessians. The equilibrium geometry of the
dimer differs from that determined by a standard optimization and the
difference becomes small only for the largest basis set (aug-cc-pVQZ).
The best theoretical estimate of the intermolecular oxygen-oxygen
distance (2.92 Angstrom) is shorter than the experimental result of 2.95
Angstrom. An estimate of the complete basis set limit of the
stabilization energy was obtained by extrapolating the stabilization
energies as a function of the reciprocal size of the basis set; this
value (21.05 kJ mol(-1)) is slightly smaller than other literature
estimates. Adding the changes due to zero-point energy and
temperature-dependent enthalpy terms (determined using anharmonic
frequencies obtained from the CP-corrected Hessian) we obtain an
estimate to the theoretical stabilization enthalpy at 375 K (12.76 kJ
mol(-1)) which is by 0.8-1.3 kJ mol(-1) smaller than the literature
results. Our theoretical value supports the very low limit of the
experimental value. Red shift of the O-H stretching frequency
accompanying formation of the dimer was determined at various
theoretical levels and best agreement with the experimental value was
found for anharmonic frequencies calculated with CP-corrected Hessians.,
DOI = 10.1039/a902109d,
ISSN = 1463-9076,
Unique-ID = ISI:000081545200003,
P. Hobza and Z. Havlas, "The fluoroform center dot center dot center dot ethylene oxide complex
exhibits a C-H center dot center dot center dot O anti-hydrogen bond," CHEMICAL PHYSICS LETTERS, vol. 303, iss. 3-4, pp. 447-452, 1999.
[Bibtex]
@article ISI:000079900700030,
Author = Hobza, P and Havlas, Z,
Title = The fluoroform center dot center dot center dot ethylene oxide complex
exhibits a C-H center dot center dot center dot O anti-hydrogen bond,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1999,
Volume = 303,
Number = 3-4,
Pages = 447-452,
Month = APR 9,
Abstract = A new, recently discovered type of intermolecular bond, called an
anti-hydrogen bond, is found in the fluoroform ethylene oxide complex.
The complex structure and properties were predicted on the basis of
counterpoise-corrected gradient optimization performed at a correlated
ab initio level. Formation of the C-H ... O anti-hydrogen bond is
manifested by an 0.1 pm contraction of the C-H bond and a significant
(similar to 30 cm(-1)) blue-shift of the C-H stretching frequency,
accompanied by a lowering of intensity of the respective vibration. In
contrast to previous cases, the studied C-H ... O anti-hydrogen bond
originates from dipole-dipole electrostatic interaction. The fluoroform
molecule a has properly oriented dipole moment vector, the size of which
is further enhanced by the C-H bond contraction. (C) 1999 Elsevier
Science B.V. All rights reserved.,
DOI = 10.1016/S0009-2614(99)00217-1,
ISSN = 0009-2614,
Unique-ID = ISI:000079900700030,
MP2 and CCSD(T) ab initio quantum chemical calculations (vol 288, pg 20,
1998)," CHEMICAL PHYSICS LETTERS, vol. 303, iss. 1-2, pp. 248, 1999.
[Bibtex]
@article ISI:000079525900038,
Author = Burda, JV and Hobza, P and Zahradnik, R,
Title = (HX)(2) species (X = F through At) in the groups of the periodic system:
MP2 and CCSD(T) ab initio quantum chemical calculations (vol 288, pg 20,
1998),
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1999,
Volume = 303,
Number = 1-2,
Pages = 248,
Month = APR 2,
ISSN = 0009-2614,
Unique-ID = ISI:000079525900038,
J. Sponer, M. Sabat, J. Burda, J. Leszczynski, and P. Hobza, "Interaction of the adenine-thymine Watson-Crick and adenine-adenine
reverse-Hoogsteen DNA base pairs with hydrated group IIa (Mg2+, Ca2+,
Sr2+, Ba2+) and IIb (Zn2+, Cd2+, Hg2+) metal cations: Absence of the
base pair stabilization by metal-induced polarization effects," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 103, iss. 13, pp. 2528-2534, 1999.
[Bibtex]
@article ISI:000079612000027,
Author = Sponer, J and Sabat, M and Burda, JV and Leszczynski, J and Hobza, P,
Title = Interaction of the adenine-thymine Watson-Crick and adenine-adenine
reverse-Hoogsteen DNA base pairs with hydrated group IIa (Mg2+, Ca2+,
Sr2+, Ba2+) and IIb (Zn2+, Cd2+, Hg2+) metal cations: Absence of the
base pair stabilization by metal-induced polarization effects,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 1999,
Volume = 103,
Number = 13,
Pages = 2528-2534,
Month = APR 1,
Abstract = Structures and energetics of complexes between the adenine-thymine
Watson-Crick (AT WC) and adenine-adenine reverse-Hoogsteen (AA rH) DNA
base pairs and hydrated (five water molecules) Mg2+, Ca2+, Sr2+, Ba2+,
Zn2+, Cd2+, and Hg2+ metal cations were studied using high-level quantum
chemical techniques. Binding of the cations to N7 of adenine does not
enhance the strength of the base pairing through polarization effects.
This is in stark contrast with the results obtained for the GG and GC
base pairs. This finding and other recently published data indicate a
qualitative difference between adenine-containing (AA,AT) and
guanine-containing (GC,GG) base pairs. There are significant changes in
the electronic structure of the guanine aromatic system upon cation
binding to N7 which propagate toward the H-bonded partner. No such
effect has been observed for any adenine-containing pair. The
interaction between hydrated cations and adenine is much weaker than
that between hydrated cations and guanine due to the low dipole moment
of adenine. Furthermore, the cation and its surrounding polarized water
molecules interact with the nitrogen atom of the adenine amino group
which then acts as an H-bond acceptor. This can lead to destabilization
of the base pairing. The zinc and magnesium groups of divalent cations
have a different balance of the water-cation and base-cation
interactions. Binding of the zinc-group elements to nucleobases is more
efficient. Interaction of large IIa group divalent cations (Ca2+, Sr2+,
and mainly Ba2+) with the N7 site of adenine is not likely unless the
amino group nitrogen atom serves as a coordination center which may
disrupt the base pairing. The complexes were optimized within the
Hartree-Fock approximation with the 6-31 G* basis set of atomic
orbitals and relativistic pseudopotentials for the cations. All atoms of
the base pairs were kept coplanar. No other constraints were applied.
The interaction energies have been calculated with inclusion of the
electron correlation by means of the full second-order Moeller-Plesset
perturbational theory.,
DOI = 10.1021/jp983744w,
ISSN = 1089-5647,
Unique-ID = ISI:000079612000027,
O. Engkvist, P. Hobza, H. Selzle, and E. Schlag, "Benzene trimer and benzene tetramer: Structures and properties
determined by the nonempirical model (NEMO) potential calibrated from
the CCSD(T) benzene dimer energies," JOURNAL OF CHEMICAL PHYSICS, vol. 110, iss. 12, pp. 5758-5762, 1999.
[Bibtex]
@article ISI:000079172400032,
Author = Engkvist, O and Hobza, P and Selzle, HL and Schlag, EW,
Title = Benzene trimer and benzene tetramer: Structures and properties
determined by the nonempirical model (NEMO) potential calibrated from
the CCSD(T) benzene dimer energies,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1999,
Volume = 110,
Number = 12,
Pages = 5758-5762,
Month = MAR 22,
Abstract = The energetics and structure of the benzene trimer and tetramer are
investigated with the nonempirical model (NEMO) potential calibrated to
high precision by comparison with CCSD(T) benzene dimer energies. From
the obtained potential energy surface, possible configurations could be
determined and the experimental observed structures could be identified.
This potential also reproduces the binding energies and allows for the
determination of all intermolecular modes. It could be shown that this
potential is therefore well suited and important to predict the
structure and thermodynamic data for larger clusters, which cannot be
accurately computed by ab initio quantum chemical methods. (C) 1999
American Institute of Physics. [S0021-9606(99)02512-X].,
DOI = 10.1063/1.478474,
ISSN = 0021-9606,
Unique-ID = ISI:000079172400032,
O. Shishkin, J. Sponer, and P. Hobza, "Intramolecular flexibility of DNA bases in adenine-thymine and
guanine-cytosine Watson-Crick base pairs," JOURNAL OF MOLECULAR STRUCTURE, vol. 477, iss. 1-3, pp. 15-21, 1999.
[Bibtex]
@article ISI:000078972600003,
Author = Shishkin, OV and Sponer, J and Hobza, P,
Title = Intramolecular flexibility of DNA bases in adenine-thymine and
guanine-cytosine Watson-Crick base pairs,
Journal = JOURNAL OF MOLECULAR STRUCTURE,
Year = 1999,
Volume = 477,
Number = 1-3,
Pages = 15-21,
Month = MAR 16,
Abstract = The conformational flexibility of pyrimidine rings in adenine
(A)-thymine (T) and guanine (G)-cytosine (C) Watson-Crick base pairs was
investigated at the ab initio Hartree-Fock (HF) level using 6-31G**
basis set. Transition of these rings from the planar equilibrium
conformation to a distorted sofa conformation with torsion angles of 20
degrees results in a marginal energy increase of approximately 1.3
kcal/mol for the A-T pair and 3.5 kcal/mol for the G-C pair. In the GC
pair, the simultaneous deformation of both pyrimidine rings was applied.
Comparison of ring deformation energies calculated at the HF, with
correlated levels indicates significant overestimation (up to 30\%) of
ring rigidity by the HF approximation. Reasonable correlations were
found between the out-of-plane ring vibrational frequencies and the ring
deformation energies. Formation of Watson-Crick base pairs is manifested
in prolongation of the N-H bonds within the bases which results in
significant reduction of the N-H stretching frequencies. On the basis of
the calculated increase in the C-H stretching frequency of adenine, the
existence of a third hydrogen bond of the C-H ... O type in the A-T pair
is ruled out. (C) 1999 Elsevier Science B.V. All rights reserved.,
DOI = 10.1016/S0022-2860(98)00603-6,
ISSN = 0022-2860,
Unique-ID = ISI:000078972600003,
P. Hobza, V. Spirko, Z. Havlas, K. Buchhold, B. Reimann, H. Barth, and B. Brutschy, "Anti-hydrogen bond between chloroform and fluorobenzene," CHEMICAL PHYSICS LETTERS, vol. 299, iss. 2, pp. 180-186, 1999.
[Bibtex]
@article ISI:000077888000012,
Author = Hobza, P and Spirko, V and Havlas, Z and Buchhold, K and Reimann, B and
Barth, HD and Brutschy, B,
Title = Anti-hydrogen bond between chloroform and fluorobenzene,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1999,
Volume = 299,
Number = 2,
Pages = 180-186,
Month = JAN 6,
Abstract = Accurate theoretical calculations (ab initio MP2/6-31G*
counterpoise-corrected gradient optimization, harmonic and anharmonic
vibrational analysis) on the fluorobenzene ... chloroform complex
predict a new type of bonding, termed the anti-hydrogen bond. This bond
distinguishes itself by the contraction of the C-H bond of chloroform
and a blue shift of the corresponding stretching frequency, i.e.
features opposite to those characteristic for a hydrogen bond. The
predicted blue shift was confirmed experimentally by double-resonance
infrared ion-depletion spectroscopy. The calculated blue shift of the
chloroform C-H stretching frequency (12 cm(-1)) agrees with the
experimental value of 14 cm(-1). The anti-hydrogen bond originates from
the dispersive interaction between molecules (contrary to the hydrogen
bond which is of electrostatic origin). It plays a significant role in
benzene-containing molecular clusters and is expected to be of
consequence for the structure of biomolecules. (C) 1999 Elsevier Science
B.V. All rights reserved.,
DOI = 10.1016/S0009-2614(98)01264-0,
ISSN = 0009-2614,
Unique-ID = ISI:000077888000012,
1998
D. Chapman, F. Hompf, K. Muller-Dethlefs, E. Waterstradt, P. Hobza, and V. Spirko, "Structure and dynamics of the phenol-water-argon cation radical," CHEMICAL PHYSICS, vol. 239, iss. 1-3, pp. 417-428, 1998.
[Bibtex]
@article ISI:000077819600034,
Author = Chapman, DM and Hompf, FJ and Muller-Dethlefs, K and Waterstradt, E and
Hobza, P and Spirko, V,
Title = Structure and dynamics of the phenol-water-argon cation radical,
Journal = CHEMICAL PHYSICS,
Year = 1998,
Volume = 239,
Number = 1-3,
Pages = 417-428,
Month = DEC 15,
Abstract = The phenol-water-argon system has been studied by ab initio methods and
by ZEKE spectroscopy. Two structures of the cation radical were found;
one has the argon sitting above the hydrogen bond, and the other has the
argon linear with an OH bond in the water. It was found that the argon
has little effect on the phenol-water moiety. The only notable change
upon argon complexation is a shortening of the hydrogen bond. Two
low-frequency vibrational progressions with spacings of 18.5 and 24.9
cm(-1) were observed in the ZEKE spectrum. Ab initio calculations reveal
that they are due to bending motions of the argon against the
phenol-water moiety. The stretching mode of the argon is not seen in the
ZEKE spectrum but is predicted to occur around 50 cm(-1). The energies
of the two minima are strongly dependent on the calculation used. At the
UMP2/cc-pVDZ level, the structure with the argon sitting on the hydrogen
bond has the lowest energy. On consideration of Franck-Condon factors,
this structure is the most likely candidate for the true experimental
structure. (C) 1998 Elsevier Science B.V. All rights reserved.,
DOI = 10.1016/S0301-0104(98)00360-7,
ISSN = 0301-0104,
Unique-ID = ISI:000077819600034,
J. Vacek, P. Hobza, and J. Jortner, "Nuclear dynamics of benzene(center dot center dot center dot)(Ar)(n)
clusters," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 102, iss. 43, pp. 8268-8278, 1998.
[Bibtex]
@article ISI:000076639700008,
Author = Vacek, J and Hobza, P and Jortner, J,
Title = Nuclear dynamics of benzene(center dot center dot center dot)(Ar)(n)
clusters,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 1998,
Volume = 102,
Number = 43,
Pages = 8268-8278,
Month = OCT 22,
Abstract = In this paper we report on constant energy molecular dynamics (MD)
simulations of nuclear dynamics of benzene-Ar and benzene-Ar-n (n = 2-7)
clusters, utilizing the ab initio intermolecular potential of
benzene-Ar. The dissociation dynamics of benzene-Ar resulting from a
nonselective excitation of the intermolecular modes exhibits an excess
energy dependence which can be accounted for in terms of the
Rice-Ramsperger-Kassel-Marcus (RRKM) statistical theory. The
time-resolved isomerization dynamics of benzene-Ar-2 and rigid nonrigid
isomerization of benzene-Ar, (n = 2-7) was investigated. The
intracluster vibrational energy redistribution (ICVR) in benzene-Ar from
an intramolecular vibration to the intermolecular modes is inefficient
on the nanosecond time scale for all of the tone quantum or two quanta)
vibrational excitation of each mode. The mode selectivity of the ICVR
and its linear dependence on the excess vibrational energy were
established. The vibrational predissociation (VP) times for single-mode
excitations of benzene-Ar are also slow on the nanosecond time scale
(>22 ns), in accord with experimental data. The retardation of ICVR and
VP of benzene-Ar reflects the bottleneck effect for intracluster
vibrational energy flow, due to the considerable frequency mismatch
between the high-frequency vibrational modes of benzene (omega =
402-2955 cm(-1)) and the low-frequency van der Waals vibrational modes
(omega = 26 and 40 cm(-1)).,
DOI = 10.1021/jp971943u,
ISSN = 1089-5639,
Unique-ID = ISI:000076639700008,
P. Hobza and Z. Havlas, "Counterpoise-corrected potential energy surfaces of simple H-bonded
systems," THEORETICAL CHEMISTRY ACCOUNTS, vol. 99, iss. 6, pp. 372-377, 1998.
[Bibtex]
@article ISI:000077029500004,
Author = Hobza, P and Havlas, Z,
Title = Counterpoise-corrected potential energy surfaces of simple H-bonded
systems,
Journal = THEORETICAL CHEMISTRY ACCOUNTS,
Year = 1998,
Volume = 99,
Number = 6,
Pages = 372-377,
Month = OCT,
Abstract = Geometries and stabilization energies of various simple II-bonded
complexes (water dimer, hydrogen fluoride dimer, formamide dimer, formic
acid dimer) have been determined by a gradient optimization that
eliminates the basis set superposition error (BSSE) by the counterpoise
(CP) method in each gradient cycle as well as by the standard gradient
optimization. Both optimization methods lead to different potential
energy surfaces (PES). The difference depends on the theoretical level
used and is larger if correlation energy is considered. Intermolecular
distances from the CP-corrected PES are consistently longer, and this
difference might be significant (similar to 0.1 Angstrom); also angular
characteristics determined from both surfaces differ significantly.
Different geometries were obtained even when passing to larger basis
sets (aug-cc-pVDZ). The standard optimization procedure can result in a
completely wrong structure. For example, the ``quasi-linear''
structure of the (HF)(2) (global minimum) does not exist at the standard
MP2/6-31G** PES (where only cyclic structure was detected) and is
found only at the CP-corrected PES. Stabilization energies obtained from
the CP-corrected PES are always larger than these from the standard PES
where the BSSE is added only a posteriori for the final optimized
structure; both energies converge only when passing to a larger basis
set (aug-cc-pVDZ).,
DOI = 10.1007/s002140050034,
ISSN = 1432-881X,
Unique-ID = ISI:000077029500004,
P. Hobza and Z. Havlas, "Counterpoise-corrected potential energy surfaces of simple
hydrogen-bonded systems," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 63, iss. 9, pp. 1343-1354, 1998.
[Bibtex]
@article ISI:000076016400005,
Author = Hobza, P and Havlas, Z,
Title = Counterpoise-corrected potential energy surfaces of simple
hydrogen-bonded systems,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1998,
Volume = 63,
Number = 9,
Pages = 1343-1354,
Month = SEP,
Abstract = Geometric and energetic characteristics of various simple
hydrogen-bonded complexes (water dimer, hydrogen fluoride dimer,
formamide dimer, formic acid dimer, glycine dimer) have been studied by
gradient optimization, which a priori eliminates the basis set
superposition error (BSSE) by using the counterpoise (CP) method, as
well as by the standard gradient optimization. Calculations were done at
the Hartree-Fock, correlated MP2 and DFT levels with small- and
medium-basis sets. The CP-corrected and standard PESs differ, depending
on the theoretical level used. Larger differences were found if the
correlation energy was included. Intermolecular distances from the
CP-corrected PES are consistently longer, and the respective difference
may be significant (approximate to 0.1 Angstrom). The stabilization
energies obtained from the CP-corrected PES are always larger than those
from the standard PES. Optimization at the standard PES might result in
a wrong structure. For example, the ``quasi-linear'' structure of the
(HF), (global minimum) does not exist at the standard MP2/6-31G**
and DFT/B3LYP/6-31G** PESs and it is found only when passing to the
respective CP-corrected PESs.,
DOI = 10.1135/cccc19981343,
ISSN = 0010-0765,
Unique-ID = ISI:000076016400005,
M. Kratochvil, O. Engkvist, J. Sponer, P. Jungwirth, and P. Hobza, "Uracil dimer: Potential energy and free energy surfaces. Ab initio
beyond Hartree-Fock and empirical potential studies," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 102, iss. 35, pp. 6921-6926, 1998.
[Bibtex]
@article ISI:000075744300008,
Author = Kratochvil, M and Engkvist, O and Sponer, J and Jungwirth, P and Hobza,
P,
Title = Uracil dimer: Potential energy and free energy surfaces. Ab initio
beyond Hartree-Fock and empirical potential studies,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 1998,
Volume = 102,
Number = 35,
Pages = 6921-6926,
Month = AUG 27,
Abstract = The first complete theoretical analysis of the gas-phase formation of a
nucleic acid base pair (uracil dimer) has been performed. The study is
based on a combination of AMBER 4.1 empirical potential, correlated ab
initio quantum chemical methods, computer simulations, and statistical
thermodynamical methods. In total, 11 low-energy minima structures were
located on the potential energy surface of the uracil dimer: seven of
them are H-bonded, one is T-shaped, and three correspond to various
stacked arrangements. The most stable structure is a H-bonded dimer with
two N-1-H ... O-2 H-bonds, designated as HB4; it has an energy minimum
of -15.9 kcal/mol at the MP2/6-31G*(0.25)//HF/6-31G** level of
theory. T-shaped structure and stacked structures are less stable than
H-bonded ones. Thermodynamic characteristics were obtained using the
rigid rotor-harmonic oscillator-ideal gas (RR-HO-IG) approximation
adopting the AMBER 4.1 and ab initio characteristics. Furthermore, the
population of various structures was determined by computer simulations
in the NVT canonical and NVE microcanonical ensembles. Results obtained
from the RR-HO-IG approximation and the NVT ensemble are very similar
and differ from the result of the NVE ensemble. The present analysis
demonstrates that different gas-phase experimental techniques can be
used for investigating different regions of the conformational space for
nucleic acid base pairs. The fact that entropy is always significant and
differs for H-bonded and stacked structures is of importance.,
DOI = 10.1021/jp9816418,
ISSN = 1089-5639,
Unique-ID = ISI:000075744300008,
base triplets by divalent metal cations," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 16, iss. 1, pp. 139-143, 1998.
[Bibtex]
@article ISI:000075718400015,
Author = Sponer, J and Sabat, M and Burda, JV and Doody, AM and Leszczynski, J
and Hobza, P,
Title = Stabilization of the purine center dot purine center dot pyrimidine DNA
base triplets by divalent metal cations,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1998,
Volume = 16,
Number = 1,
Pages = 139-143,
Month = AUG,
ISSN = 0739-1102,
Unique-ID = ISI:000075718400015,
J. Sponer, J. Burda, M. Sabat, J. Leszczynski, and P. Hobza, "Interaction between the guanine-cytosine Watson-Crick DNA base pair and
hydrated group IIa (Mg2+, Ca2+, Sr2+, Ba2+) and group IIb (Zn2+, Cd2+,
Hg2+) metal cations," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 102, iss. 29, pp. 5951-5957, 1998.
[Bibtex]
@article ISI:000075151200029,
Author = Sponer, J and Burda, JV and Sabat, M and Leszczynski, J and Hobza, P,
Title = Interaction between the guanine-cytosine Watson-Crick DNA base pair and
hydrated group IIa (Mg2+, Ca2+, Sr2+, Ba2+) and group IIb (Zn2+, Cd2+,
Hg2+) metal cations,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 1998,
Volume = 102,
Number = 29,
Pages = 5951-5957,
Month = JUL 16,
Abstract = Structures and energetics of complexes between the guanine-cytosine
Watson-Crick DNA base pair and pentahydrated Mg2+, Ca2+, Sr2+, Ba2+,
Zn2+, Cd2+, and Hg2+ metal cations were studied. Comparison has been
made with the data for the unsolvated cations. The complexes were fully
optimized within the Hartree-Fock approximation applying the 6-31G*
basis set of atomic orbitals, while relativistic pseudopotentials were
used for the cations except magnesium. The energetics have been studied
with the inclusion of electron correlation using the full second-order
Moller-Plesset perturbation theory. The cation with its hydration sphere
has been considered as one subsystem in the calculations of interaction
energy. Thus, the complete system for a calculation would include the
hydrated cation-guanine-cytosine trimer. The interaction between
hydrated cation and guanine is significantly reduced compared to the
guanine-unsolvated cation interaction. Though the stabilizing three-body
contribution has been reduced by almost 50\% by hydration, it still
remains significant. The stability of the guanine-cytosine Watson-Crick
base pair is enhanced by ca. 20-30\% due to the coordination of the
hydrated cation. All the transition metal and Mg2+ cations are tightly
bound to the N7 atom of guanine, constituting an octahedral coordination
sphere. The Ca2+, Sr2+, and Ba2+ cations are coordinated simultaneously
to the N7 and O6 atoms of guanine and the base-cation distance increases
with the row number in this series. However, the energy difference
between the N7 and N7-O6 types of coordination is rather small. The
calculations show a different balance between the transition metal and
alkaline earth cations with respect to the cation-base and cation-water
interactions. Zn2+ compared to Mg2+ is bound more tightly to the base,
and the hydration shell around Zn2+ is more flexible. The replacement of
Mg2+ by Zn2+ can be viewed, to some extent, as a shift from the
interaction between nucleobase and a hydrated cation toward hydration of
a metalated base. This is likely to contribute to the different
biological role of Zn2+ and Mg2+.,
DOI = 10.1021/jp980769m,
ISSN = 1089-5639,
Unique-ID = ISI:000075151200029,
groups of the periodic system: Ab initio quantum chemical calculations," POLISH JOURNAL OF CHEMISTRY, vol. 72, iss. 7, S, pp. 1497-1504, 1998.
[Bibtex]
@article ISI:000075902500024,
Author = Hobza, P and Burda, JV and Zahradnik, R,
Title = Isoelectronic dimers [(XH3)(2), (YH2)(2), (ZH)(2), and (Rg)(2)] in the
groups of the periodic system: Ab initio quantum chemical calculations,
Journal = POLISH JOURNAL OF CHEMISTRY,
Year = 1998,
Volume = 72,
Number = 7, S,
Pages = 1497-1504,
Month = JUL,
Abstract = The (ZH)(2), (YH2)(2), (XH3)(2) and (Rg)(2) dimers [Z = F-At; Y = O,
Po; X = N, Bi; Rg = rare gas] were studied ab initio using the CCSD(T)
and MP2 procedures. Average relativistic effective potentials were used
for all the halogens, while Stuttgart effective core potentials were
used for the remaining non-hydrogen atoms. All the (HX)(2) structures
are H-bonded. All the stabilization energies mutually approach when
passing Gown the group of the periodic system.,
ISSN = 0137-5083,
Unique-ID = ISI:000075902500024,
J. Burda, P. Hobza, and R. Zahradnik, "(HX)(2) species (X = F through At) in the groups of the periodic system:
MP2 and CCSD(T) ab initio quantum chemical calculations," CHEMICAL PHYSICS LETTERS, vol. 288, iss. 1, pp. 20-24, 1998.
[Bibtex]
@article ISI:000073721800004,
Author = Burda, JV and Hobza, P and Zahradnik, R,
Title = (HX)(2) species (X = F through At) in the groups of the periodic system:
MP2 and CCSD(T) ab initio quantum chemical calculations,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1998,
Volume = 288,
Number = 1,
Pages = 20-24,
Month = MAY 15,
Abstract = (XH)(2) species (X = F through At) were studied ab initio using the
CCSD(T) and MP2 procedures. All-electron calculations were performed for
X = F, Cl and Br while average relativistic effective potentials were
used consistently for all the halogens. All (HX)(2) structures an
H-bonded; the HX...XH structures are less stable. (C) 1998 Elsevier
Science B.V. All rights reserved.,
DOI = 10.1016/S0009-2614(98)00262-0,
ISSN = 0009-2614,
Unique-ID = ISI:000073721800004,
P. Hobza and J. Sponer, "Significant structural deformation of nucleic acid bases in stacked base
pairs: an ab initio study beyond Hartree-Fock," CHEMICAL PHYSICS LETTERS, vol. 288, iss. 1, pp. 7-14, 1998.
[Bibtex]
@article ISI:000073721800002,
Author = Hobza, P and Sponer, J,
Title = Significant structural deformation of nucleic acid bases in stacked base
pairs: an ab initio study beyond Hartree-Fock,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1998,
Volume = 288,
Number = 1,
Pages = 7-14,
Month = MAY 15,
Abstract = Stacked structures of the uracil, thiouracil and cytosine dimers,
adenine-uracil and uracil-cytosine pairs were investigated by gradient
optimization at the ab initio second-order Moller-Plesset correlated
level. The aromatic rings of bases and exocyclic groups were
significantly distorted from planarity upon complexation. Nevertheless,
the stabilization energies were similar to those obtained previously
with rigid monomers, because the non-negligible improvement in
intermolecular stabilization energy is compensated for by the
deformation energies of the bases. The largest distortions were found
for uracil. Deformation of uracil rings leads to the formation of
intermolecular H-bonds and improves the stabilization energy. (C) 1998
Elsevier Science B.V. All rights reserved.,
DOI = 10.1016/S0009-2614(98)00238-3,
ISSN = 0009-2614,
Unique-ID = ISI:000073721800002,
P. Hobza, V. Spirko, H. Selzle, and E. Schlag, "Anti-hydrogen bond in the benzene dimer and other carbon proton donor
complexes," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 102, iss. 15, pp. 2501-2504, 1998.
[Bibtex]
@article ISI:000073271200001,
Author = Hobza, P and Spirko, V and Selzle, HL and Schlag, EW,
Title = Anti-hydrogen bond in the benzene dimer and other carbon proton donor
complexes,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 1998,
Volume = 102,
Number = 15,
Pages = 2501-2504,
Month = APR 9,
Abstract = A new type of bonding, termed anti-hydrogen bond, is identified in the
benzene dimer and other carbon proton donor complexes from correlated ab
initio computations. Gradient optimization of the benzene dimer at the
MP2/6-31G* and MP2/6-31G** levels shows a shortening of the C-H
bond of the proton donor and a blue-shift of the corresponding C-H
stretching frequency. The harmonic C-H stretching vibrational frequency
shift agrees well with that evaluated for various anharmonic approaches.
The blue-shift of the C-H stretching frequency was also found in the
case of benzene complexes with other carbon proton donors, CH4 and
CHCl3. The anti-H-bonds are expected to be very significant for the
structure and dynamics of biomolecules.,
DOI = 10.1021/jp973374w,
ISSN = 1089-5639,
Unique-ID = ISI:000073271200001,
1997
J. Sponer, J. Leszczynski, and P. Hobza, "Thioguanine and thiouracil: Hydrogen-bonding and stacking properties," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 101, iss. 49, pp. 9489-9495, 1997.
[Bibtex]
@article ISI:A1997YL17400042,
Author = Sponer, J and Leszczynski, J and Hobza, P,
Title = Thioguanine and thiouracil: Hydrogen-bonding and stacking properties,
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 1997,
Volume = 101,
Number = 49,
Pages = 9489-9495,
Month = DEC 4,
Abstract = Base stacking and H-bonding properties of thioguanine and thiouracils
were studied using an ab initio quantum chemical method with inclusion
of electron correlation (second-order Moller-Plesset perturbational
method). Hydrogen-bonded base pairs containing thiobases are only
slightly less stable (up to 2 kcal/mol) than the unmodified base pairs.
The N ... S distances are larger by 0.4-0.7 Angstrom compared to the N
... O distances in the standard base pairs. The thio group enhances
polarizability of the monomers and their dipole moments. Thus, in
stacked complexes of thiobases, both dispersion attraction and
electrostatic interactions are enhanced. Mutual contact of the sulfur
atoms and their interaction with second-row elements lead to steric
clashes destabilizing the stacking, though, in DNA, such clashes should
be eliminated by rather small adjustments of the local DNA conformation.
The thio group significantly destabilizes the hydration of the
6-position of thioguanine with respect to guanine. The first hydration
shell in the major groove might be significantly altered by thioguanine.,
DOI = 10.1021/jp9720404,
ISSN = 1089-5639,
Unique-ID = ISI:A1997YL17400042,
J. Burda, J. Sponer, J. Leszczynski, and P. Hobza, "Interaction of DNA base pairs with various metal cations (Mg2+, Ca2+,
Sr2+, Ba2+, Cu+, Ag+, Au+, Zn2+, Cd2+, and Hg2+): Nonempirical ab initio
calculations on structures, energies, and nonadditivity of the
interaction," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 101, iss. 46, pp. 9670-9677, 1997.
[Bibtex]
@article ISI:A1997YG46300036,
Author = Burda, JV and Sponer, J and Leszczynski, J and Hobza, P,
Title = Interaction of DNA base pairs with various metal cations (Mg2+, Ca2+,
Sr2+, Ba2+, Cu+, Ag+, Au+, Zn2+, Cd2+, and Hg2+): Nonempirical ab initio
calculations on structures, energies, and nonadditivity of the
interaction,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 1997,
Volume = 101,
Number = 46,
Pages = 9670-9677,
Month = NOV 13,
Abstract = Interaction of Watson-Crick adenine-thymine (AT) and guanine-cytosine
(GC) base pairs with various metal (M) cations (Mg2+,..., Hg2+) were
studied by nonempirical ab initio methods with inclusion of correlation
energy. Cations were allowed to interact with the N7 nitrogen of adenine
and the N7 and O6 atoms of guanine. All of the cations were described by
Christiansen's average relativistic effective potentials using the DZ+P
basis set, while the 6-31G** basis set was used for the elements of
base pairs. Disruption of the adenine-thymine as well as
guanine-cytosine pairs in the presence of all studied cations is
energetically more demanding than that for isolated base pairs; the
addition stabilization of the base pair is about 100\% for complexes
with dication. The interaction is highly nonadditive. The three-body
term is for the MGC complex considerably larger than that for MAT; the
intercomplex charge transfer is also much larger for the former complex.,
DOI = 10.1021/jp963753+,
ISSN = 1089-5647,
Unique-ID = ISI:A1997YG46300036,
P. Hobza, J. Sponer, and J. Leszczynski, "Electron-correlated calculations of electric properties of nucleic acid
bases - Comment," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 101, iss. 40, pp. 8038-8039, 1997.
[Bibtex]
@article ISI:A1997XZ20200023,
Author = Hobza, P and Sponer, J and Leszczynski, J,
Title = Electron-correlated calculations of electric properties of nucleic acid
bases - Comment,
Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
Year = 1997,
Volume = 101,
Number = 40,
Pages = 8038-8039,
Month = OCT 2,
DOI = 10.1021/jp970622f,
ISSN = 1089-5647,
Unique-ID = ISI:A1997XZ20200023,
P. Hobza, M. Kabelac, J. Sponer, P. Mejzlik, and J. Vondrasek, "Performance of empirical potentials (AMBER, CFF95, CVFF, CHARMM, OPLS,
POLTEV), semiempirical quantum chemical methods (AM1, MNDO/M, PM3), and
ab initio Hartree-Fock method for interaction of DNA bases: Comparison
with nonempirical beyond Hartree-Fock results," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 18, iss. 9, pp. 1136-1150, 1997.
[Bibtex]
@article ISI:A1997XG19500003,
Author = Hobza, P and Kabelac, M and Sponer, J and Mejzlik, P and Vondrasek, J,
Title = Performance of empirical potentials (AMBER, CFF95, CVFF, CHARMM, OPLS,
POLTEV), semiempirical quantum chemical methods (AM1, MNDO/M, PM3), and
ab initio Hartree-Fock method for interaction of DNA bases: Comparison
with nonempirical beyond Hartree-Fock results,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 1997,
Volume = 18,
Number = 9,
Pages = 1136-1150,
Month = JUL 15,
Abstract = Empirical energy functions (AMBER 4.1, CFF95, CHARMM23, OPLS, Poltev),
semiempirical quantum chemical methods (AM1, MNDO/M, PM3), and the
nonempirical ab initio self-consistent field (SCF) method utilizing a
minimal basis set combined with the London dispersion energy (SCFD
method) were used for calculation of stabilization energies of 26
H-bonded DNA base pairs, 10 stacked DNA base pairs (thymine was replaced
by uracil), and the B-DNA decamer (only DNA bases were considered).
These energies were compared with nonempirical ab initio beyond
Hartree-Fock values [second-order Moller-Plesset
(MP2)/6-31G*(0.25)]. The best performance was exhibited by AMBER 4.1
with the force field of Cornell et al. The SCFD method, tested for
H-bonded pairs only, exhibited stabilization energies that were too
large. Semiempirical quantum chemical methods gave poor agreement with
MP2 values in the H-bonded systems and failed completely for stacked
pairs. A similar failure was recently reported for density functional
theory calculations on base stacking. It may be concluded that currently
available force fields provide much better descriptions of interactions
of nucleic acid bases than the semiempirical methods and low-level ab
initio treatment. (C) 1997 by John Wiley \& Sons, Inc.,
DOI = 10.1002/(SICI)1096-987X(19970715)18:9<1136::AID-JCC3>3.3.CO;2-I,
ISSN = 0192-8651,
Unique-ID = ISI:A1997XG19500003,
A quantum-chemical study," BIOPHYSICAL JOURNAL, vol. 73, iss. 1, pp. 76-87, 1997.
[Bibtex]
@article ISI:A1997XF77600008,
Author = Sponer, J and Gabb, HA and Leszczynski, J and Hobza, P,
Title = Base-base and deoxyribose-base stacking interactions in B-DNA and Z-DNA:
A quantum-chemical study,
Journal = BIOPHYSICAL JOURNAL,
Year = 1997,
Volume = 73,
Number = 1,
Pages = 76-87,
Month = JUL,
Abstract = Base-stacking interactions in canonical and crystal B-DNA and in Z-DNA
steps are studied using the ab initio quantum-chemical method with
inclusion of electron correlation. The stacking energies in canonical
B-DNA base-pair steps vary from -9.5 kcal/mol (GG) to -13.2 kcal/mol
(GC), The many-body nonadditivity term, although rather small in
absolute value, influences the sequence dependence of stacking energy,
The base-stacking energies calculated for CGC and a hypothetical TAT
sequence in Z-configuration are similar to those in B-DNA. Comparison
with older quantum-chemical studies shows that they do not provide even
a qualitatively correct description of base stacking. We also evaluate
the base-(deoxy)ribose slacking geometry that occurs in Z-DNA and in
nucleotides linked by 2',5'-phosphodiester bonds. Although the molecular
orbital analysis does not rule out the charge-transfer n-pi(*)
interaction of the sugar 04' with the aromatic base, the base-sugar
contact is stabilized by dispersion energy similar to that of stacked
bases. The stabilization amounts to almost 4 kcal/mol and is thus
comparable to that afforded by normal base-base stacking. This
enhancement of the total stacking interaction could contribute to the
propensity of short d(CG)(n) sequences to adopt the Z-conformation.,
ISSN = 0006-3495,
Unique-ID = ISI:A1997XF77600008,
cations: Ab initio quantum-chemical and empirical potential study," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 14, iss. 5, pp. 613-628, 1997.
[Bibtex]
@article ISI:A1997WW02600008,
Author = Sponer, J and Burda, JV and Mejzlik, P and Leszczynski, J and Hobza, P,
Title = Hydrogen-bonded trimers of DNA bases and their interaction with metal
cations: Ab initio quantum-chemical and empirical potential study,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1997,
Volume = 14,
Number = 5,
Pages = 613-628,
Month = APR,
Abstract = Neutral (G.GC, A.AT, G.AT, T.AT, and C(imino).GC) and protonated (CH+.GC
and AH(+).GC) hydrogen-bonded trimers of nucleic acid bases were
characterized by ab initio methods with the inclusion of electron
correlation. In addition, the influence of metal cations on the
third-strand binding in Purine-Purine-Pyrimidine (Pu.PuPy)
reverse-Hoogsteen triplets has been studied. The ab initio calculations
were compared with those from recently introduced force fields
(AMBER4.1, CHARMM23, and CFF95). The three-body term in neutral trimers
is mostly negligible, and the use of empirical potentials is justified.
The only exception is the neutral G.GC Hoogsteen trimer with a
three-body term of -4 kcal/mol. Protonated trimers are stabilized by
molecular ion - molecular dipole attraction and the interaction within
the complex is nonadditive, with the three-body term on the order of -3
kcal/mol. There is a significant induction interaction between the
third-strand protonated base and guanine. The calculations indicate an
enhancement of the third-strand binding in the G.GC reverse-Hoogsteen
trimer due to metal cation coordination to the N7/O6 position of the
third-strand guanine. Interactions between metal cations and complexes
of DNA bases are in general highly nonadditive; the three-body term is
above -10 kcal/mol in a complex of a divalent cation (Ca2+) with the GG
reverse-Hoogsteen pair. The pairwise additive empirical potentials
qualitatively underestimate the binding energy between cation and base.,
ISSN = 0739-1102,
Unique-ID = ISI:A1997WW02600008,
J. Sponer and P. Hobza, "MP2 and CCSD(T) study on hydrogen bonding, aromatic stacking and
nonaromatic stacking," CHEMICAL PHYSICS LETTERS, vol. 267, iss. 3-4, pp. 263-270, 1997.
[Bibtex]
@article ISI:A1997WN57000010,
Author = Sponer, J and Hobza, P,
Title = MP2 and CCSD(T) study on hydrogen bonding, aromatic stacking and
nonaromatic stacking,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1997,
Volume = 267,
Number = 3-4,
Pages = 263-270,
Month = MAR 21,
Abstract = Three groups of molecular clusters were studied using the coupled
cluster method with non-iterative triple excitations (CCSD(T)) and the
second-order Moller-Plesset perturbational method (MP2): H-bonded DNA
base pairs ((cytosine)(2), (isocytosine)(2) and (uracil)(2)), aromatic
stacked complexes ((pyrrol)(2), (pyrimidine)(2), (triazine)(2),
(aminotriazine)(2), (4-aminopyrimidine)(2) and (1-aminopyrimidine)(2))
and cyclic H-bonded and stacked (formamide)(2) and (formamidine)(2)
dimers. The higher-order correlation energy contributions are repulsive
in all aromatic stacked clusters, while for all other systems the
CCSD(T) and MP2 methods provide nearly identical results. The
interaction energies of stacked complexes converge with the size of
basis set much faster than the interaction energies of H-bonded
clusters. It follows from the present data that the stacking energies of
nucleic acid base pairs, evaluated at the MP2 level with
diffuse-polarized medium-sized basis sets should be close to the actual
values. The stabilization of H-bonded base pairs evaluated at the same
level of theory is expected to be underestimated.,
DOI = 10.1016/S0009-2614(97)00118-8,
ISSN = 0009-2614,
Unique-ID = ISI:A1997WN57000010,
J. Burda, P. Hobza, and R. Zahradnik, "Properties and reactivity in groups of the periodic system: Ion-molecule
reactions HX+HX(center dot+) (X=F, Cl, Br, I, At)," JOURNAL OF PHYSICAL CHEMISTRY A, vol. 101, iss. 6, pp. 1134-1139, 1997.
[Bibtex]
@article ISI:A1997WL09000020,
Author = Burda, JV and Hobza, P and Zahradnik, R,
Title = Properties and reactivity in groups of the periodic system: Ion-molecule
reactions HX+HX(center dot+) (X=F, Cl, Br, I, At),
Journal = JOURNAL OF PHYSICAL CHEMISTRY A,
Year = 1997,
Volume = 101,
Number = 6,
Pages = 1134-1139,
Month = FEB 6,
Abstract = The radical cations of hydrogen halogenide dimers (HX)(2)(.+) (X = F-At)
and products of their decomposition have been investigated, using
beyond-Hartree-Fock methods (MP2, QCISD, and CCSD(T)). Both all-electron
and pseudopotentials techniques were considered. The (HF)(2)(.+) system
differs significantly from the remaining (HX)(2)(.+) systems. The energy
barrier height for transfering the H-bonded system to the hemibond
structure is very low, causing the spontaneous conversion of the
H-bonded structures to the hemibond ones, with the exception of the
(HF)(2)(.+) dimer where the inverse situation exists. The
characteristics for the overall process HX + HX(.+) reversible arrow
H(2)X(+) + X(.) were obtained from the experimental heats of formation
and from calculated characteristics. The Delta H-298 values based on the
pseudopotentials are satisfactory for the F- and Cl-containing systems;
however, the agreement is less satisfactory for heavier systems.,
DOI = 10.1021/jp961152c,
ISSN = 1089-5639,
Unique-ID = ISI:A1997WL09000020,
pairs," JOURNAL OF CHEMICAL PHYSICS, vol. 106, iss. 4, pp. 1472-1479, 1997.
[Bibtex]
@article ISI:A1997WE31200022,
Author = Spirko, V and Sponer, J and Hobza, P,
Title = Anharmonic and harmonic intermolecular vibrational modes of the DNA base
pairs,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1997,
Volume = 106,
Number = 4,
Pages = 1472-1479,
Month = JAN 22,
Abstract = Intermolecular vibrational modes of the H-bonded adenine...thymine
Watson-Crick (AT) base pair were studied for the first time using
multidimensional nonharmonic treatment. Relying on a
Born-Oppenheimer-like separation of the fast and slow vibrational
motions, the complete multidimensional vibrational problem is reduced to
a six-dimensional subproblem in which all rearrangements between the
pair fragments (i.e., adenine and thymine) can be described. Following
the Hougen-Bunker-Johns approach and using appropriate vibrational
coordinates, a nonrigid reference is defined which covers all motions on
the low-lying part of the intermolecular potential surface and which
facilitates the derivation of a suitable model Hamiltonian. The
potential energy surface is determined at the ab initio Hartree-Fock
level with minimal basis set (HF/MINI-1) and an analytic potential
energy function is obtained by fitting to the ab initio data. This
function is used to calculate vibrational energy levels and effective
geometries within the framework of the model Hamiltonian, disregarding
the role of the kinematic and potential (in-plane)-(out-of-plane)
interactions. The calculations are in reasonable agreement with the
normal coordinate analysis (harmonic treatment) thus indicating physical
correctness of this standard approach for an approximate description of
the lowest vibrational states of the AT base pair. In addition, to get a
deeper insight, harmonic vibrational frequencies of the AT pair and 28
other base pairs are evaluated at the same and higher levels of theory
[ab initio Hartree-Fock level with split-valence basis set
(HF/6-31G**)]. The HF/MINI-1 and HF/6-31G** intermolecular
harmonic vibrational frequencies differ by less than 30\%. For all the
base pairs, the buckle and propeller vibrational modes [for definition
and nomenclature see R. E. Dickerson et al., EMBO J. 8, 1 (1989)] are
the lowest ones, all being in the narrow interval (from 4 to 30 cm(-1)
in the harmonic approximation). Although most of the evaluated harmonic
frequencies are qualitatively correct approximations to the genuine
vibrational frequencies, in some cases due to a strong nonharmonic
behavior of the buckle motion, they become physically meaningless. To
get physically correct results in such cases, apparently, the standard
harmonic oscillator approach should be replaced by a more adequate
approach, for instance, by the approach we used in the case of the
adenine...thymine pair. (C) 1997 American Institute of Physics.,
ISSN = 0021-9606,
Unique-ID = ISI:A1997WE31200022,
1996
aminotriazine are nonplanar: Results of correlated ab initio quantum
chemical calculations and anharmonic analysis of the aniline inversion
motion," JOURNAL OF CHEMICAL PHYSICS, vol. 105, iss. 24, pp. 11042-11050, 1996.
[Bibtex]
@article ISI:A1996VZ37100041,
Author = Bludsky, O and Sponer, J and Leszczynski, J and Spirko, V and Hobza, P,
Title = Amino groups in nucleic acid bases, aniline, aminopyridines, and
aminotriazine are nonplanar: Results of correlated ab initio quantum
chemical calculations and anharmonic analysis of the aniline inversion
motion,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1996,
Volume = 105,
Number = 24,
Pages = 11042-11050,
Month = DEC 22,
Abstract = The amino group nonplanarity in nucleic acid bases, aniline,
aminopyridines, and aminotriazine was investigated by ab initio methods
with and without inclusion of correlation energy utilizing medium and
extended basis sets. For all the systems studied, the amino group was
found to be nonplanar and the coupled cluster method [CCSD(T)]
`'nonplanarities'' and inversion barriers slightly higher than their
second-order many-body perturbation-theory (MP2) counterparts. To assess
the reliability of the calculations, inversion splittings for aniline
and aniline-ND2 were evaluated by solving a two-dimensional vibrational
Schrodinger equation for the large-amplitude inversion and torsion
motions, while respecting the role of small-amplitude C-N stretching and
H-N-H bending motions. Because a large number of points is required for
the description of the aniline potential energy surface, the
Hartree-Fock (HF) method with 6-31G* basis set was utilized. The
vibrational calculations were performed within the framework of the
semirigid bender Hamiltonian of Landsberg and Bunker. Excellent
agreement between experimental and theoretical inversion-torsion
frequencies for fundamental, overtone, and combination modes was found,
which gives strong evidence for the adequacy of the theoretical model
used in general, and potential energy surface in particular. Similarity
between the HF, MP2, and CCSD(T) aniline inversion barriers and amino
group nonplanarities gives us confidence that the MP2 and CCSD(T)
inversion barriers and amino group nonplanarities of the DNA bases,
aminopyridine, and aminotriazine, are close to the actual values which
are still experimentally unknown. (C) 1996 American Institute of
Physics.,
ISSN = 0021-9606,
Unique-ID = ISI:A1996VZ37100041,
dot center dot center dot formamide and formamidine center dot center
dot center dot formamidine dimers," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 388, pp. 115-120, 1996.
[Bibtex]
@article ISI:A1996WE80900016,
Author = Hobza, P and Sponer, J,
Title = MP2 and CCSD(T) calculations on H-bonded and stacked formamide center
dot center dot center dot formamide and formamidine center dot center
dot center dot formamidine dimers,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1996,
Volume = 388,
Pages = 115-120,
Month = DEC 11,
Note = 4th Annual Conference on Current Trends in Computational Chemistry
(CCTCC), VICKSBURG, MS, NOV 03-04, 1995,
Abstract = H-bonded and stacked structures of formamide ... formamide and
formamidine ... formamidine pairs were studied at the MP2 and CCSD(T)
theoretical levels. The H-bonded structures of both pairs are
considerably more stable than the stacked ones. The MP2 and CCSD(T)
stabilization energies of H-bonded as well as of stacked structures
differ only marginally, and the H-bonded structure agrees with
literature data.,
ISSN = 0166-1280,
Unique-ID = ISI:A1996WE80900016,
B. Schneider, M. Kabelac, and P. Hobza, "Geometry of the phosphate group and its interactions with metal cations
in crystals and ab initio calculations," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 118, iss. 48, pp. 12207-12217, 1996.
[Bibtex]
@article ISI:A1996VX05500026,
Author = Schneider, B and Kabelac, M and Hobza, P,
Title = Geometry of the phosphate group and its interactions with metal cations
in crystals and ab initio calculations,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 1996,
Volume = 118,
Number = 48,
Pages = 12207-12217,
Month = DEC 4,
Abstract = The phosphate geometry was studied in crystal environment by analyzing
178 crystal structures and in vacuo by ab initio calculations of
(di)hydrogen and dimethyl phosphates and a diphosphate model system,
CH3OP(O-2)O(CH2)(3)OP(O-2)OCH3 (diPh), at the MP2 and HF levels. Since
charge determines the phosphate stereochemistry, uncharged, -1, and -2
phosphates were analyzed separately. The P=O and O=P=O bonding
parameters depend only on charge and the number of carbon substituents
while the remaining parameters depend also on substituent type; the
largest sensitivity was observed for the C-O and C-O-P parameters. An
acceptable agreement between the crystal and ab initio geometries was
obtained only when basis sets contained polarization functions and a
model system included a counterion (Na+). In uncharged and -1
phosphates, the C-O-P-O(-C) torsion angles prefer the +/-sc regions.
These phosphates substituted by cyclic C-sp3 noncyclic C-sp3, or C-ar
carbons have characteristic torsion distributions. Conclusion from both
analysis of crystal data and from theoretical calculations is that the
internal phosphate geometry is sensitive to a counterion position as
well as to values of the C-O-P-O(-C) torsion angles. Most metal cations
interact directly with the charged oxygens in -1 phosphates while in
many -2 phosphates, this interaction is mediated by water molecules. The
distributions of Na+ around -1 and -2 phosphates are localized into two
principal sites which Lie outside the O=P=O plane and interact with only
one of the charged oxygens. In contrast, theoretically predicted
positions are located symmetrically between the charged oxygens in the
O=P=O plane. The cation positions around dimethyl phosphate and a model
diPh compound mimicking the B-DNA backbone were virtually identical. The
discrepancy between these theoretical positions and the sites derived
from the crystal data was significantly reduced by incorporation of a
single water molecule into the theoretical model. Therefore, both
cations and polar particles, particularly water molecules, should be
considered when properties of the phosphate group are described.,
DOI = 10.1021/ja9621152,
ISSN = 0002-7863,
Unique-ID = ISI:A1996VX05500026,
P. Hobza, H. Selzle, and E. Schlag, "Potential energy surface for the benzene dimer. Results of ab initio
CCSD(T) calculations show two nearly isoenergetic structures: T-shaped
and parallel-displaced," JOURNAL OF PHYSICAL CHEMISTRY, vol. 100, iss. 48, pp. 18790-18794, 1996.
[Bibtex]
@article ISI:A1996VV35400021,
Author = Hobza, P and Selzle, HL and Schlag, EW,
Title = Potential energy surface for the benzene dimer. Results of ab initio
CCSD(T) calculations show two nearly isoenergetic structures: T-shaped
and parallel-displaced,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1996,
Volume = 100,
Number = 48,
Pages = 18790-18794,
Month = NOV 28,
Abstract = It is proposed that the benzene dimer has two almost isoenergetic
structures. This has been confirmed by very high level ab initio
calculations. MP2, MP4, and CCSD(T) calculations with various basis sets
up to the augmented correlation consistent polarized double-zeta
(aug-cc-pvdz) one were performed for the sandwich (S), T-shaped (T), and
parallel-displaced (PD) structures of the benzene dimer. MP2 strongly
overestimates the stabilization energy and leads to incorrect global
minimum. Also, the MP4 predictions differ from the CCSD(T) ones. At the
CCSD(T) level the T structure was the most stable structure with
stabilization energy of about 2.3 kcal/mol. The PD structure at the same
level was found to be slightly less stable (by 0.2-0.3 kcal/mol). The
energy difference between these structures is sensitive to the
theoretical level applied, and we estimated that both structures are
similarly stable. The absolute value of stabilization energy is believed
to be close to the genuine value; this conclusion was based on study of
basis set saturation where basis sets up to [4s3p2d1f] were utilized.
Performance of existing empirical potentials is evaluated. The existence
of the C-H ...pi H-bond was not confirmed. Finally, consequences of the
existence of two similarly stable structures of the benzene dimer for
the structure and function of proteins are discussed.,
DOI = 10.1021/jp961239y,
ISSN = 0022-3654,
Unique-ID = ISI:A1996VV35400021,
P. Hobza and J. Sponer, "Thermodynamic characteristics for the formation of H-bonded DNA base
pairs," CHEMICAL PHYSICS LETTERS, vol. 261, iss. 3, pp. 379-384, 1996.
[Bibtex]
@article ISI:A1996VN63700026,
Author = Hobza, P and Sponer, J,
Title = Thermodynamic characteristics for the formation of H-bonded DNA base
pairs,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1996,
Volume = 261,
Number = 3,
Pages = 379-384,
Month = OCT 18,
Abstract = Thermodynamic characteristics for the formation of gas-phase H-bonded
DNA base pairs were evaluated using ab initio data (geometries and
vibrational frequencies of bases and base pairs and base pair
stabilization energies) utilizing the rigid rotor - harmonic oscillator
- ideal gas approximations. While the stabilization energies for various
DNA base pairs differ considerably (by more than 200\%), the respective
entropy terms are more uniform and vary by less than 40\%. Calculated
values are compared with experimental interaction enthalpies and
equilibrium constants obtained from field-ionization mass spectrometry
and supersonic beam experiments, respectively. The agreement in the
former case was good, while in the latter, a deep disagreement was
found; the validity of supersonic beam experiments is argued.
Equilibrium constants for the formation of DNA base pairs obtained by
the free energy perturbation/molecular dynamics method differ from the
respective ab initio values.,
DOI = 10.1016/0009-2614(96)00954-2,
ISSN = 0009-2614,
Unique-ID = ISI:A1996VN63700026,
J. Burda, R. Zahradnik, P. Hobza, and M. Urban, "Dimers of rare gas atoms: CCSD(T), CCSDT and FCI calculations on the
(He)(2) dimer, CCSD(T) and CCSDT calculations on the (Ne)(2) dimer, and
CCSD(T) all-electron and pseudopotential calculations on the dimers from
(Ne)(2) through (Xe)(2)," MOLECULAR PHYSICS, vol. 89, iss. 2, pp. 425-432, 1996.
[Bibtex]
@article ISI:A1996VM76500005,
Author = Burda, JV and Zahradnik, R and Hobza, P and Urban, M,
Title = Dimers of rare gas atoms: CCSD(T), CCSDT and FCI calculations on the
(He)(2) dimer, CCSD(T) and CCSDT calculations on the (Ne)(2) dimer, and
CCSD(T) all-electron and pseudopotential calculations on the dimers from
(Ne)(2) through (Xe)(2),
Journal = MOLECULAR PHYSICS,
Year = 1996,
Volume = 89,
Number = 2,
Pages = 425-432,
Month = OCT 10,
Abstract = Rare gas atom dimers from (He)(2) to (Xe)(2) were studied by beyond
Hartree-Fock methods and the results obtained were compared with
experimental values. In the case of (He)(2), the CCSD(T), CCSDT, and FCI
results enable estimation of the role of triple and quadruple
excitations. CCSD(T) already yields reliable stabilization energy
values. Passing from CCSD(T) to CCSDT leads to only a small increase in
the stabilization energy; a very similar value was surprisingly obtained
for the (Ne)(2) dimer. For the (Ne)(2) and (Ar)(2) dimers, the
all-electron and the effective core potential (ECP) results were
compared. Correcting the ECP CCSD(T) characteristics for (Kr)(2) and
(Xe)(2) by the factors found for (Ne)(2) and (Ar)(2) resulted in very
good agreement with the experimental values.,
DOI = 10.1080/002689796173804,
ISSN = 0026-8976,
Unique-ID = ISI:A1996VM76500005,
ab initio studies," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 14, iss. 1, pp. 117-135, 1996.
[Bibtex]
@article ISI:A1996VG12600014,
Author = Sponer, J and Leszczynski, J and Hobza, P,
Title = Hydrogen bonding and stacking of DNA bases: A review of quantum-chemical
ab initio studies,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1996,
Volume = 14,
Number = 1,
Pages = 117-135,
Month = AUG,
Abstract = Ab initio quantum-chemical calculations with inclusion of electron
correlation made since 1994 (such reliable calculations were not
feasible before) significantly modified our view on interactions of
nucleic acid bases. These calculations allowed to perform the first
reliable comparison of the strength of stacked and hydrogen bonded pairs
of nucleic acid bases, and to characterize the nature of the base-base
interactions. Although hydrogen-bonded complexes of nucleobases are
primarily stabilized by the electrostatic interaction, the dispersion
attraction is also important. The stacked pairs are stabilized by
dispersion attraction, however, the mutual orientation of stacked bases
is determined rather by the electrostatic energy. Some popular theories
of stacking were ruled out: The theory based on attractive interactions
of polar exocyclic groups of bases with delocalized electrons of the
aromatic rings (Bugg er at, Biopolymers 10, 175 (1971).), and the Pi-Pi
interactions model (C.A. Hunter, J. Mol. Biol. 230, 1025 (1993)). The
calculations demonstrated that amino groups of nucleobases are very
flexible and intrinsically nonplanar, allowing hydrogen-bond-like
interactions which are oriented out of the plane of the nucleobase. Many
H-bonded DNA base pairs are intrinsically nonplanar. Higher-level ab
initio calculations provide a unique set of reliable and consistent data
for parametrization and verification of empirical potentials. In this
article, we present a short survey of the recent calculations, and
discuss their significance and limitations. This summary is written for
readers which are not experts in computational quantum chemistry.,
ISSN = 0739-1102,
Unique-ID = ISI:A1996VG12600014,
P. Hobza, F. Hubalek, M. Kabelac, P. Mejzlik, J. Sponer, and J. Vondrasek, "Ability of empirical potentials (AMBER, CHARMM, CVFF, OPLS, Poltev) and
semi-empirical quantum chemical methods (AM1, MNDO/M, PM3) to describe
H-bonding in DNA base pairs; Comparison with ab initio results," CHEMICAL PHYSICS LETTERS, vol. 257, iss. 1-2, pp. 31-35, 1996.
[Bibtex]
@article ISI:A1996UY12200005,
Author = Hobza, P and Hubalek, F and Kabelac, M and Mejzlik, P and Sponer, J and
Vondrasek, J,
Title = Ability of empirical potentials (AMBER, CHARMM, CVFF, OPLS, Poltev) and
semi-empirical quantum chemical methods (AM1, MNDO/M, PM3) to describe
H-bonding in DNA base pairs; Comparison with ab initio results,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1996,
Volume = 257,
Number = 1-2,
Pages = 31-35,
Month = JUL 19,
Abstract = Various empirical potentials (AMBER 3.0, AMBER 4.1, CHARMM 23, CVFF,
OPLS, Poltev) and semi-empirical quantum chemical methods (AM1, PM3,
MNDO/M) were tested to reproduce the ab initio MP2 stabilization
energies of DNA H-bonded base pairs (26 different base pairs). The best
performance of an empirical potential is exhibited by AMBER 4.1 and of
semi-empirical quantum chemical methods by MNDO/M.,
DOI = 10.1016/0009-2614(96)00537-4,
ISSN = 0009-2614,
Unique-ID = ISI:A1996UY12200005,
calculations with three empirical potential models and density
functional theory calculations," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 17, iss. 7, pp. 841-850, 1996.
[Bibtex]
@article ISI:A1996UF06600008,
Author = Sponer, J and Leszczynski, J and Hobza, P,
Title = Base stacking in cytosine dimer. A comparison of correlated ab initio
calculations with three empirical potential models and density
functional theory calculations,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 1996,
Volume = 17,
Number = 7,
Pages = 841-850,
Month = MAY,
Abstract = Ab initio MP2/6-31G* interaction energies were calculated for more
than 80 geometries of stacked cytosine dimer. Diffuse polarization
functions were used to properly cover the dispersion energy. The results
of ab initio calculations were compared with those obtained from three
electrostatic empirical potential models, constructed as the sum of a
Lennard-Jones potential (covering dispersion and repulsion
contributions) and the electrostatic term. Point charges and point
multipoles of the electrostatic term were also obtained at the
MP2/6-31G* level of theory. The point charge MEP model (atomic charges
derived from molecular electrostatic potential) satisfactorily
reproduced the ab initio data. Addition of pi-charges localized below
and above the cytosine plane did not affect the calculated energies. The
model employing the distributed multipole analysis gave worse agreement
with the ab initio data than the MEP approach. The MP2 MEP charges were
also derived using larger sets of atomic orbitals: cc-pVDZ, 6-311 +
G(2d,p), and aug-cc-pVDZ. Differences between interaction energies
calculated using these three sets of point charges and the MP2/6-31G*
charges were smaller than 0.8 kcal/mol. The correlated ab initio
calculations were also compared with the density functional theory (DFT)
method. DFT calculations well reproduced the electrostatic part of
interaction energy. They also covered some nonelectrostatic short-range
effects which were not reproduced by the empirical potentials. The DFT
method does not include the dispersion energy. This energy, approximated
by an empirical term, was therefore added to the DFT interaction energy.
The resulting interaction energy exhibited an artifact secondary minimum
for a 3.9-4.0 A vertical separation of bases. This defect is inherent in
the DFT functionals, because it is not observed for the Hartree-Fock +
dispersion interaction energy. (C) 1996 by John Wiley * Sons, Inc.,
ISSN = 0192-8651,
Unique-ID = ISI:A1996UF06600008,
J. Burda, J. Sponer, and P. Hobza, "Ab Initio study of the interaction of guanine and adenine with various
mono- and bivalent metal cations (Li+, Na+, K+, Rb+, Cs+; Cu+, Ag+, Au+;
Mg2+, Ca2+, Sr2+, Ba2+; Zn2+, Cd2+, and Hg2+)," JOURNAL OF PHYSICAL CHEMISTRY, vol. 100, iss. 17, pp. 7250-7255, 1996.
[Bibtex]
@article ISI:A1996UG82300053,
Author = Burda, JV and Sponer, J and Hobza, P,
Title = Ab Initio study of the interaction of guanine and adenine with various
mono- and bivalent metal cations (Li+, Na+, K+, Rb+, Cs+; Cu+, Ag+, Au+;
Mg2+, Ca2+, Sr2+, Ba2+; Zn2+, Cd2+, and Hg2+),
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1996,
Volume = 100,
Number = 17,
Pages = 7250-7255,
Month = APR 25,
Abstract = The interaction of guanine and adenine with ions of groups Ia, Ib, IIa,
and IIb were studied at the Hartree-Fock and second-order Moller-Plesset
levels employing all-electron (AE) and pseudopotential treatments.
Christiansen's average relativistic effective pseudopotentials (AREP)
were used for all the ions with the exception of Li+. AE and AREP
treatments were tested for the Na+, K+, Mg2+, and Ca2+ complexes; very
good agreement between the results suggests that pseudopotentials can be
used with confidence also for other cations. Intermolecular X-N7
distances for complexes containing adenine are shorter than those for
complexes containing guanine. The stabilization energies for guanine ...
X complexes are larger than those of adenine ... X complexes.
Relativistic effects are most pronounced for Au+ and Hg2+ ions.,
DOI = 10.1021/jp952941h,
ISSN = 0022-3654,
Unique-ID = ISI:A1996UG82300053,
J. Sponer and P. Hobza, "Nonempirical ab initio calculations on DNA base pairs," CHEMICAL PHYSICS, vol. 204, iss. 2-3, pp. 365-372, 1996.
[Bibtex]
@article ISI:A1996UD54300022,
Author = Sponer, J and Hobza, P,
Title = Nonempirical ab initio calculations on DNA base pairs,
Journal = CHEMICAL PHYSICS,
Year = 1996,
Volume = 204,
Number = 2-3,
Pages = 365-372,
Month = APR 1,
Abstract = 28 H-bonded DNA base pairs formed by guanine, adenine, thymine and
cytosine were optimized by the gradient method at the ab initio
HF/MINI-1 level. 10 pairs were found to be nonplanar with propeller
structure. Harmonic vibration analysis indicates that all the stationary
points found correspond to energy minima. The calculated interaction
enthalpies (sum of the SCF interaction energy, the dispersion energy and
the zero-point energy) are larger than the respective experimental data
due to overestimation of the MINI-1 SCF interaction energy. Buckling and
propeller vibrations were found to be the lowest for all the pairs; it
is therefore possible to expect that all the pairs are flexible toward
buckle and propeller vibrations, The H-bonded structure of the cytosine
dimer was found to be considerably more stable than the stacked
structures; both structures were studied at the higher MP2/6-31G*
level. The reliability of the procedure used (MP2/6-31G*) was tested
for model clusters (formamide formamidine, benzene Ar) at higher levels
(MP4, CCSD(T)).,
DOI = 10.1016/0301-0104(95)00311-8,
ISSN = 0301-0104,
Unique-ID = ISI:A1996UD54300022,
[Bibtex]
@article ISI:A1996UJ09000009,
Author = Sponer, J and Florian, J and Hobza, P and Leszczynski, J,
Title = Nonplanar DNA base pairs,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1996,
Volume = 13,
Number = 5,
Pages = 827-833,
Month = APR,
Abstract = Three-dimensional structures of a representative set of more than 30
hydrogen-bonded nucleic acids base pairs have been studied by reliable
ab initio quantum mechanical methods. We show that many hydrogen-bonded
nucleic acid base pairs are intrinsically nonplanar, mainly due to the
partial sp(3) hybridization of nitrogen atoms of their amino groups and
secondary electrostatic interactions. This finding extends the
variability of intermolecular interactions of DNA bases in that i)
flexibility of the base pairs is larger than has been assumed before,
and ii) attractive proton-proton acceptor interactions oriented out of
the base pair plane are allowed. For example, ail four G ... A mismatch
base pairs are propeller twisted, and the energy preferences for the
nonplanar structures range from less than 0.1 kcal/mol to 1.8 kcal/mol.
We predict that nonplanarity of the amino group of guanine in the
G(anti)... A(anti) pair of the ApG step of the d(CCAAGATTGG)(2) crystal
structure is an important stabilizing factor that improves the energy of
this structure by almost 3 kcal/mol. Currently used empirical potentials
are not accurate enough to properly cover the interactions associated
with amino-group and base-pair nonplanarity.,
ISSN = 0739-1102,
Unique-ID = ISI:A1996UJ09000009,
J. Sponer, J. Leszczynski, and P. Hobza, "Nature of nucleic acid-base stacking: Nonempirical ab initio and
empirical potential characterization of 10 stacked base dimers.
Comparison of stacked and H-bonded base pairs," JOURNAL OF PHYSICAL CHEMISTRY, vol. 100, iss. 13, pp. 5590-5596, 1996.
[Bibtex]
@article ISI:A1996UC39800062,
Author = Sponer, J and Leszczynski, J and Hobza, P,
Title = Nature of nucleic acid-base stacking: Nonempirical ab initio and
empirical potential characterization of 10 stacked base dimers.
Comparison of stacked and H-bonded base pairs,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1996,
Volume = 100,
Number = 13,
Pages = 5590-5596,
Month = MAR 28,
Abstract = Ab initio (MP2/6-31G*(0.25)) interaction energies were calculated for
almost 240 geometries of 10 stacked nucleic acid-base pairs: A ... A, C
... C, G ... G, U ... U, A ... C, G ... A, A ... U, G ... C, C ... U,
and G ... U; in some cases uracil was replaced by thymine. The most
stable stacked pair is the G ... G dimer (-11.3 kcal/ mel), and the
least stable is the uracil dimer (-6.5 kcal/mol). The interaction
energies of H-bonded base pairs range from -25.8 kcal/mol (G ... C) to
-10.6 kcal/mol (T ... T). The stability of stacked pairs originates in
the electron correlation, while all the H-bonded pairs are dominated by
the HF energy. The mutual orientation of the stacked bases is, however,
primarily determined by the HF interaction energy. The ab initio base
stacking energies are well reproduced by the empirical potential
calculations, provided the atomic charges are derived by the same method
as used in the ab initio calculations. Some contributions previously
postulated to significantly influence base stacking (induction
interactions, pi-pi interactions) were not found. Base stacking was also
investigated in six B-DNA and two Z-DNA base pair steps; their
geometries were taken from the oligonucleotide crystal data. The
many-body correction was estimated at the HF/MINI-1 level. The
sequence-dependent variations of the total base pair step stacking
energies range from -9.9 to -14.7 kcal/mol, The range of the calculated
many-body corrections to the stacking energy is 2 kcal/mol. The ab
initio calculations exclude the consideration that the unusual
conformational properties of the CpA(TpG) steps might be associated with
attractive induction interactions of the exocyclic groups of DNA bases
and the aromatic rings of bases.,
DOI = 10.1021/jp953306e,
ISSN = 0022-3654,
Unique-ID = ISI:A1996UC39800062,
J. Sponer and P. Hobza, "DNA base amino groups and their role in molecular interactions: Ab
initio and preliminary density functional theory calculations," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 57, iss. 5, pp. 959-970, 1996.
[Bibtex]
@article ISI:A1996TR90300016,
Author = Sponer, J and Hobza, P,
Title = DNA base amino groups and their role in molecular interactions: Ab
initio and preliminary density functional theory calculations,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1996,
Volume = 57,
Number = 5,
Pages = 959-970,
Month = MAR 5,
Note = 8th International Congress of Quantum Chemistry, PRAGUE, CZECH REPUBLIC,
JUN 19-23, 1994,
Abstract = Interactions of DNA bases frequently involve the DNA base amino groups.
In contrast to the empirical force fields, the ab initio calculations
predict nonplanar DNA base amino groups. The same conclusion also
follows from the density functional theory (DFT) calculations. Both
local and nonlocal density approximations were used. Optimized
geometries of two other molecules with nonplanar amino groups (aniline,
formamidine) are presented for comparison. The influence of nonplanar
DNA base amino groups on the conformational variability of DNA is
discussed. (C) 1996 John Wiley \& Sons, Inc.,
DOI = 10.1002/(SICI)1097-461X(1996)57:5<959::AID-QUA16>3.0.CO;2-S,
ISSN = 0020-7608,
Unique-ID = ISI:A1996TR90300016,
P. Hobza, O. Bludsky, H. Selzle, and E. Schlag, "Ab initio calculations on the structure, vibrational frequencies, and
valence excitation energies of the benzene center dot center dot center
dot Ar and benzene center dot center dot center dot Ar-2 cluster," CHEMICAL PHYSICS LETTERS, vol. 250, iss. 3-4, pp. 402-408, 1996.
[Bibtex]
@article ISI:A1996TZ54900023,
Author = Hobza, P and Bludsky, O and Selzle, HL and Schlag, EW,
Title = Ab initio calculations on the structure, vibrational frequencies, and
valence excitation energies of the benzene center dot center dot center
dot Ar and benzene center dot center dot center dot Ar-2 cluster,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1996,
Volume = 250,
Number = 3-4,
Pages = 402-408,
Month = MAR 1,
Abstract = Excitation spectra of van der Waals (vdW) clusters show spectral shifts
due to change in the stabilization energy in the ground and excited
state. Ab initio calculations are applied to determine the structure and
vibrational frequencies of vdW clusters like benzene...Ar and
benzene...Ar-2 in the electronic excited state. The calculation gives
values for the valence excitation energy and intermolecular vibrations
which are in good agreement with experimental data.,
DOI = 10.1016/0009-2614(96)00008-5,
ISSN = 0009-2614,
Unique-ID = ISI:A1996TZ54900023,
J. Vacek and P. Hobza, "On the thermodynamic characteristics of the benzene center dot center
dot center dot Ar-2 complex: An application of the ab initio
intermolecular potential," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 57, iss. 4, pp. 551-557, 1996.
[Bibtex]
@article ISI:A1996TR62200003,
Author = Vacek, J and Hobza, P,
Title = On the thermodynamic characteristics of the benzene center dot center
dot center dot Ar-2 complex: An application of the ab initio
intermolecular potential,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1996,
Volume = 57,
Number = 4,
Pages = 551-557,
Month = FEB 15,
Abstract = The benzene ... Ar-2 cluster was studied by constant energy molecular
dynamics simulations using the ab initio intermolecular potential for
the benzene ... Ar interaction. The relative population of the
energetically less favorable one-sided structure was found to be higher
that the population of the global minimum (two-sided structure). The
preference of the energetically less stable structure was explained by
the entropy effect. The thermodynamic functions (entropy, internal
energy, and free energy) were calculated independently by integration of
the canonical distribution function. (C) 1996 John Wiley \& Sons, Inc.,
DOI = 10.1002/(SICI)1097-461X(1996)57:4<551::AID-QUA3>3.0.CO;2-X,
ISSN = 0020-7608,
Unique-ID = ISI:A1996TR62200003,
role of molecular ion-dipole and induction interactions," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 13, iss. 4, pp. 695-706, 1996.
[Bibtex]
@article ISI:A1996TZ04100013,
Author = Sponer, J and Leszczynski, J and Vetterl, V and Hobza, P,
Title = Base stacking and hydrogen bonding in protonated cytosine dimer: The
role of molecular ion-dipole and induction interactions,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1996,
Volume = 13,
Number = 4,
Pages = 695-706,
Month = FEB,
Abstract = An ab initio quantum-chemical study of stacked and hydrogen-bonded
protonated cytosine dimer has been carried out. The calculations were
made using the second-order Moller-Plesset perturbational method (MP2)
with a medium-sized polarized set of atomic orbitals. H-bonded as well
as stacked protonated base pairs are more stable than the neutral base
pairs. Two energy contributions not present in the neutral base pairs
stabilize the protonated base pairs: the molecular ion - dipole
interaction, and the induction interaction. The molecular ion - dipole
stabilization dominates in base pairs with highly polar neutral
monomers, such as the (CCH+)-C-... base pair. The induction interaction
is not included in the commonly used empirical potentials, which do not
reproduce the changes in intermolecular stabilization due to
protonation. We demonstrate that the base stacking of several
consecutive (CCH+)-C-... pairs, as proposed for polycytidylic acid and
i-DNA, is strongly repulsive. We also show that the intermolecular
interactions strongly prefer protonation of adenine in protonated
adenine-cytosine pairs.,
ISSN = 0739-1102,
Unique-ID = ISI:A1996TZ04100013,
J. Sponer, J. Leszczynski, and P. Hobza, "Structures and energies of hydrogen-bonded DNA base pairs. A
nonempirical study with inclusion of electron correlation," JOURNAL OF PHYSICAL CHEMISTRY, vol. 100, iss. 5, pp. 1965-1974, 1996.
[Bibtex]
@article ISI:A1996TT53300073,
Author = Sponer, J and Leszczynski, J and Hobza, P,
Title = Structures and energies of hydrogen-bonded DNA base pairs. A
nonempirical study with inclusion of electron correlation,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1996,
Volume = 100,
Number = 5,
Pages = 1965-1974,
Month = FEB 1,
Abstract = Hydrogen bonding of DNA bases was investigated by reliable nonempirical
ab initio calculations. Gradient optimization was carried out on 30 DNA
base pairs using the Hartree-Fock (HF) approximation and the 6-31G**
basis set of atomic orbitals. The optimizations were performed within
C-s symmetry. However, the harmonic vibrational analysis indicates that
13 of the studied base pairs are intrinsically nonplanar. Interaction
energies of base pairs were then evaluated at the planar optimized
geometries with inclusion of the electron correlation energy using the
second-order Moller-Plesset (MP2) method. The stabilization energies of
the studied base pairs range from -24 to -9 kcal/mol, and the calculated
gas phase interaction enthalpies agree well (within 2 kcal/mol) with the
available experimental values. The binding energies and molecular
structures of the base pairs are not determined solely by the hydrogen
bonds, but they are also strongly influenced by the polarity of the
monomers and by a wide variety of secondary long-range electrostatic
interactions that also involve the hydrogen atoms bonded to ring carbon
atoms. The stabilization of the base pairs is dominated by the
Hartree-Fock interaction energy. This result confirms that the stability
of the base pairs originates in the electrostatic interactions. For
weakly bonded base pairs, the correlation interaction energy amounts to
as much as 30-40\% of the stabilization. For some other bask pairs,
however, repulsive correlation interaction energy was found. The latter
fact is explained as a result of a reduction of the electrostatic
attraction upon inclusion of the electron correlation. The empirical
London dispersion energy does not reproduce the correlation interaction
energy. For the sake of comparison, results of a first gradient
optimization for a DNA base pair at a correlated level (CC base pair,
MP2/6-31G** level) are reported. In addition, the ability of the
economical density functional theory (DFT) method to reproduce the ab
initio data was investigated. The DFT method with present functionals is
not suitable to consistently study the whole range of the DNA base
interactions. However, it gives good estimates of interaction energies
at the reference HF/6-31G** geometries.,
DOI = 10.1021/jp952760f,
ISSN = 0022-3654,
Unique-ID = ISI:A1996TT53300073,
1995
J. VACEK and P. HOBZA, "GAS-PHASE SOLVATION OF BENZENE BY 2-8 ARGON ATOMS - A MOLECULAR-DYNAMICS
STUDY WITH AB-INITIO INTERMOLECULAR POTENTIAL," JOURNAL OF PHYSICAL CHEMISTRY, vol. 99, iss. 47, pp. 17088-17092, 1995.
[Bibtex]
@article ISI:A1995TF81100008,
Author = VACEK, J and HOBZA, P,
Title = GAS-PHASE SOLVATION OF BENZENE BY 2-8 ARGON ATOMS - A MOLECULAR-DYNAMICS
STUDY WITH AB-INITIO INTERMOLECULAR POTENTIAL,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1995,
Volume = 99,
Number = 47,
Pages = 17088-17092,
Month = NOV 23,
Abstract = Benzene ... Ar-n clusters (n = 2, 3, 5, 7, 8) were studied by
constant-energy molecular dynamics simulations using an ab initio
intermolecular potential for the benzene ... Ar interaction. Stationary
points for each cluster were generated by the quenching technique. For
clusters with n greater than or equal to 3, the relative populations of
energetically less favorable two-sided and bridgelike structures were
found to be higher than the population of global minima having one-sided
structures. For benzene ... Ar-2, the relative population of the global
minimum (two-sided structure) was found to be lower than the population
of the local minimum with the one-sided structure. The preference of
bridged and two-sided structures for clusters with n greater than or
equal to 3 and one-sided structure for benzene ... Ar-2 is due to the
entropy. A textbook example is the benzene ... Ar-8 cluster where the
global minimum having seven argons on one side of the benzene ring and
one argon on the opposite side is populated 5-8 times less than the less
stable minimum with a bridgelike structure.,
DOI = 10.1021/j100047a008,
ISSN = 0022-3654,
Unique-ID = ISI:A1995TF81100008,
P. HOBZA, J. SPONER, and T. RESCHEL, "DENSITY-FUNCTIONAL THEORY AND MOLECULAR CLUSTERS," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 16, iss. 11, pp. 1315-1325, 1995.
[Bibtex]
@article ISI:A1995TA40300001,
Author = HOBZA, P and SPONER, J and RESCHEL, T,
Title = DENSITY-FUNCTIONAL THEORY AND MOLECULAR CLUSTERS,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 1995,
Volume = 16,
Number = 11,
Pages = 1315-1325,
Month = NOV,
Abstract = Density functional theory (DFT) methods, including nonlocal density
gradient terms in the exchange and correlation energy functionals, were
applied to various types of molecular clusters: H-bonded, ionic,
electrostatic, and London. Reliable results on the structure and
stabilization energy were obtained for the first two types of cluster as
long as Becke3LYP and Becke3P86 functionals and basis sets of at least
DZ + P quality were used. DFT methods with currently available
functionals failed completely, however, for London-type clusters, for
which no minimum was found on the potential energy surfaces. DFT
interaction energy exhibits the same basis set extension dependence as
the Hartree-Fock (HF) interaction energy. Therefore, the Boys-Bernardi
function counterpoise procedure should be employed for elimination of
the DFT basis set superposition error. (C) 1995 by John Wiley \& Sons,
Inc.,
DOI = 10.1002/jcc.540161102,
ISSN = 0192-8651,
Unique-ID = ISI:A1995TA40300001,
THEIR RETENTION BEHAVIOR AND ENANTIOSEPARATION ON THE BETA-CYCLODEXTRIN
STATIONARY-PHASE IN HPLC," HRC-JOURNAL OF HIGH RESOLUTION CHROMATOGRAPHY, vol. 18, iss. 9, pp. 597-601, 1995.
[Bibtex]
@article ISI:A1995TE82300016,
Author = TESAROVA, E and GILAR, M and HOBZA, P and KABELAC, M and DEYL, Z and
SMOLKOVAKEULEMANSOVA, E,
Title = CORRELATION BETWEEN STRUCTURE OF DIHYDROPYRIDINE CALCIUM-ANTAGONISTS AND
THEIR RETENTION BEHAVIOR AND ENANTIOSEPARATION ON THE BETA-CYCLODEXTRIN
STATIONARY-PHASE IN HPLC,
Journal = HRC-JOURNAL OF HIGH RESOLUTION CHROMATOGRAPHY,
Year = 1995,
Volume = 18,
Number = 9,
Pages = 597-601,
Month = SEP,
Abstract = Chromatographic data for five dihydropyridine calcium antagonists (CAs)
were obtained on beta-cyclodextrin column in the reversed phase HPLC,
Interaction energies of solute-cyclodextrin complexes formed by docking
of different parts of the CAs' molecules into the cyclodextrin cavity
were calculated, Results from the HPLC experiments and molecular
modeling were compared. It was found that several types of inclusion
complexes are energetically possible and contribute to the retention
simultaneously, Only certain inclusion complexes are assumed to be
responsible for enantioseparation of CAs. Nevertheless molecular
modeling studies are a useful tool for explaining the enantioselectivity
and predicting the elution order of enantiomers.,
ISSN = 0935-6304,
Unique-ID = ISI:A1995TE82300016,
P. HOBZA, J. SPONER, and M. POLASEK, "H-BONDED AND STACKED DNA-BASE PAIRS - CYTOSINE DIMER - AN AB-INITIO
2ND-ORDER MOLLER-PLESSET STUDY," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 117, iss. 2, pp. 792-798, 1995.
[Bibtex]
@article ISI:A1995QC77600023,
Author = HOBZA, P and SPONER, J and POLASEK, M,
Title = H-BONDED AND STACKED DNA-BASE PAIRS - CYTOSINE DIMER - AN AB-INITIO
2ND-ORDER MOLLER-PLESSET STUDY,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 1995,
Volume = 117,
Number = 2,
Pages = 792-798,
Month = JAN 18,
Abstract = H-Bonded and stacked structures of the cytosine dimer were studied at
the MP2/6-31G* ab initio level. In addition, the electrostatic energy
was estimated separately using correlated distributed multipole analysis
(CDMA) with atomic multipoles calculated at the MP2/6-31G* level. The
H-bonded structure is more stable; the stabilization of the optimal
stacked structure is, however, quite large and constitutes almost 50\%
of the H-bonded pair stabilization. The dominant part of the H-bonded
stabilization originates in the electrostatic interaction. The
dispersion energy is responsible for the stabilization in the stacked
pair, while the mutual orientation of the stacked cytosines is governed
by the electrostatic term. Due to the dipole-dipole interactions,
antiparallel arrangement of the two stacked cytosines in the isolated
cytosine dimer is strongly favored. No significant stabilization
originating in the interactions between the polar exocyclic groups and
the delocalized electrons of the aromatic rings was found. The CDMA
calculations gave good insight into the nature of the stabilization of
various complexes; however, some regions of the potential energy surface
were not satisfactorily reproduced by this method.,
DOI = 10.1021/ja00107a023,
ISSN = 0002-7863,
Unique-ID = ISI:A1995QC77600023,
1994
AN AB-INITIO QUANTUM-CHEMICAL STUDY," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 12, iss. 3, pp. 671-680, 1994.
[Bibtex]
@article ISI:A1994QD25100010,
Author = SPONER, J and HOBZA, P,
Title = G.C BASE-PAIR IN PARALLEL-STRANDED DNA - A NOVEL TYPE OF BASE-PAIRING -
AN AB-INITIO QUANTUM-CHEMICAL STUDY,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1994,
Volume = 12,
Number = 3,
Pages = 671-680,
Month = DEC,
Abstract = It was shown recently that parallel stranded DNA also incorporates the
Reverse Watson-Crick Guanine.Cytosine (RWC G.C) pair. It contains only
one hydrogen bond surrounded by mutual carbonyl group and amino group
contacts. Here we describe an ab initio quantum chemical analysis of
this unusual base pair. The conclusions can be summarized as follows.
(1) The RWC G.C base pair exhibits a previously unknown type of DNA base
pairing. (2) Its stabilization energy is estimated to be above 20
kJ/mol. A significant part of the stabilization originates in attractive
interactions between the amino group hydrogen atom on one base and lone
electron pair of the amino group nitrogen atom of the other (opposite)
base. (3) In contrast to any other base pairing patterns, observed in
the DNA molecules, the two DNA base amino groups in the RWC G.C base
pair are highly nonplanar. They can form additional bifurcated hydrogen
bonds with neighboring base pairs. Coplanarity of the two DNA base rings
is energetically acceptable. (4) The unique RWC G.C pair cannot be
analyzed by the empirical potential calculations.,
ISSN = 0739-1102,
Unique-ID = ISI:A1994QD25100010,
[Bibtex]
@article ISI:A1994PT13100001,
Author = CASTLEMAN, AW and HOBZA, P,
Title = VAN-DER-WAALS MOLECULES .2. INTRODUCTION,
Journal = CHEMICAL REVIEWS,
Year = 1994,
Volume = 94,
Number = 7,
Pages = 1721-1722,
Month = NOV,
ISSN = 0009-2665,
Unique-ID = ISI:A1994PT13100001,
P. HOBZA, H. SELZLE, and E. SCHLAG, "STRUCTURE AND PROPERTIES OF BENZENE-CONTAINING MOLECULAR CLUSTERS -
NONEMPIRICAL AB-INITIO CALCULATIONS AND EXPERIMENTS," CHEMICAL REVIEWS, vol. 94, iss. 7, pp. 1767-1785, 1994.
[Bibtex]
@article ISI:A1994PT13100003,
Author = HOBZA, P and SELZLE, HL and SCHLAG, EW,
Title = STRUCTURE AND PROPERTIES OF BENZENE-CONTAINING MOLECULAR CLUSTERS -
NONEMPIRICAL AB-INITIO CALCULATIONS AND EXPERIMENTS,
Journal = CHEMICAL REVIEWS,
Year = 1994,
Volume = 94,
Number = 7,
Pages = 1767-1785,
Month = NOV,
DOI = 10.1021/cr00031a002,
ISSN = 0009-2665,
Unique-ID = ISI:A1994PT13100003,
J. VACEK and P. HOBZA, "A MOLECULAR-DYNAMICS STUDY OF THE BENZENE...AR(N) (N=3-5) COMPLEX USING
THE AB-INITIO INTERMOLECULAR POTENTIAL," JOURNAL OF PHYSICAL CHEMISTRY, vol. 98, iss. 43, pp. 11034-11039, 1994.
[Bibtex]
@article ISI:A1994PN85800009,
Author = VACEK, J and HOBZA, P,
Title = A MOLECULAR-DYNAMICS STUDY OF THE BENZENE...AR(N) (N=3-5) COMPLEX USING
THE AB-INITIO INTERMOLECULAR POTENTIAL,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1994,
Volume = 98,
Number = 43,
Pages = 11034-11039,
Month = OCT 27,
Abstract = The benzene...Ar-n (n = 3-5) clusters were studied by constant-energy
molecular dynamics simulations using the ab initio intermolecular
potential for the benzene...Ar interaction. The relative populations of
energetically less favorable two-sided structures were found to be
higher than the populations of one-sided isomers for all the clusters
under study. The highest temperature at which the cluster can exist for
a reasonable time interval (1 ns) is about 50 K for all the clusters
investigated.,
DOI = 10.1021/j100094a009,
ISSN = 0022-3654,
Unique-ID = ISI:A1994PN85800009,
CUMULENES AND ACETYLENES," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 119, iss. 3, pp. 335-349, 1994.
[Bibtex]
@article ISI:A1994PN47000007,
Author = ZAHRADNIK, R and HOBZA, P and BURCL, R and HESS, BA and RADZISZEWSKI, JG,
Title = STRAINED UNSATURATED MOLECULES - THEORETICAL-STUDY OF ACYCLIC AND CYCLIC
CUMULENES AND ACETYLENES,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1994,
Volume = 119,
Number = 3,
Pages = 335-349,
Month = OCT 20,
Abstract = There is a high probability for the photochemical formation of highly
strained isomers of benzene, hydrocarbons 31-34, at very low
temperatures in inert matrices. This is also true for various
derivatives and analogues of o-benzyne (22), benzologues of three
isomers of benzyne (52-54), and six-membered cycles having two or three
triple CC bonds in the ring (25-27). These systems as well as the
radical ions of o-benzyne and cyclic C(n) systems (46-51) have been
studied theoretically.
The stability and structure estimates were based on non-empirical and
semi-empirical quantum chemical calculations. The reliability of these
calculations has been partly tested by comparing the calculated and
observed heats of formation for a representative ensemble of unsaturated
and strained hydrocarbons. Some of the C(n) systems (acyclic and
cyclic) can, in principle, exist in two forms which differ in their
electron distribution and therefore also in their structure.,
ISSN = 0166-1280,
Unique-ID = ISI:A1994PN47000007,
P. HOBZA, R. BURCL, V. SPIRKO, O. DOPFER, K. MULLERDETHLEFS, and E. SCHLAG, "AB-INITIO STUDY OF THE PHENOL-WATER CATION-RADICAL," JOURNAL OF CHEMICAL PHYSICS, vol. 101, iss. 2, pp. 990-997, 1994.
[Bibtex]
@article ISI:A1994NW97900016,
Author = HOBZA, P and BURCL, R and SPIRKO, V and DOPFER, O and MULLERDETHLEFS, K
and SCHLAG, EW,
Title = AB-INITIO STUDY OF THE PHENOL-WATER CATION-RADICAL,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1994,
Volume = 101,
Number = 2,
Pages = 990-997,
Month = JUL 15,
Abstract = The phenol-water cation radical has been investigated by ab initio
theory using the spin-restricted open-shell Hartree-Fock and
spin-restricted open-shell second-order Moller-Plesset theories with
3-21G*(O) and 6-31G* basis sets. The full geometrical optimization
was performed for several hydrogen-bonded structures and one hemibonded
structure. Clearly, the most stable structure has been found for C-s
symmetry with the linear hydrogen bond between the proton of the OH
group of the phenol cation radical and the oxygen of the water, and the
water hydrogens pointing away from the phenyl ring. For this structure
harmonic (and for some intermolecular modes anharmonic) vibrational
frequencies have been computed for various isotopic complexes. The
computed shifts Of phenol-localized intramolecular modes on complexation
and on deuteration as well as the calculated intermolecular frequencies
of the different isotopic complexes allow for an assignment of
vibrational frequencies observed in the experimental zero-kinetic-energy
(ZEKE) photoelectron spectra. Five out of a possible six intermolecular
vibrations and several intramolecular modes have been assigned,
including the 18b vibration which shows a strong blue shift in frequency
upon complexation. Structure and properties of the phenol-water cation
radical are compared with those of the corresponding neutral complex.,
DOI = 10.1063/1.468436,
ISSN = 0021-9606,
Unique-ID = ISI:A1994NW97900016,
COMPARISON WITH EMPIRICAL POTENTIALS," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 11, iss. 6, pp. 1357-1376, 1994.
[Bibtex]
@article ISI:A1994PC51700013,
Author = SPONER, J and BURCL, R and HOBZA, P,
Title = INTERACTIONS BETWEEN AMINO-GROUPS IN DNA - AN AB-INITIO STUDY AND A
COMPARISON WITH EMPIRICAL POTENTIALS,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1994,
Volume = 11,
Number = 6,
Pages = 1357-1376,
Month = JUN,
Abstract = An ab initio quantum chemical analysis of the close amino group
contacts, existing in many DNA crystal structures, is presented. The
calculations are made at the Hartree-Fock (HF) level with medium
6-31G* and 6-31G(NH2*) basis sets as well as with inclusion of
correlation energy using the second order Moller-Plesset theory (MP2)
with the 6-31G* basis set. We demonstrate that the model system
(methylamine dimer, cytosine dimer) amino groups are forced to adopt
significantly non-planar geometry to stabilize their mutual interaction.
Comparison is made with a representative set of empirical potentials
including AMBER, CHARMM and GROMOS. The empirical potentials are not
reliable enough to analyze the amino group contacts occurring in the DNA
double helices. We propose that the mutual amino group interactions
contribute to the conformational variability of the CpG and ApT B-DNA
steps.,
ISSN = 0739-1102,
Unique-ID = ISI:A1994PC51700013,
P. HOBZA, R. ZAHRADNIK, B. HESS, and J. RADZISZEWSKI, "AB-INITIO CALCULATIONS ON THE O-BENZYNE AR AND O-BENZYNE CO COMPLEXES," THEORETICA CHIMICA ACTA, vol. 88, iss. 3, pp. 233-241, 1994.
[Bibtex]
@article ISI:A1994NP04600005,
Author = HOBZA, P and ZAHRADNIK, R and HESS, BA and RADZISZEWSKI, JG,
Title = AB-INITIO CALCULATIONS ON THE O-BENZYNE AR AND O-BENZYNE CO COMPLEXES,
Journal = THEORETICA CHIMICA ACTA,
Year = 1994,
Volume = 88,
Number = 3,
Pages = 233-241,
Month = MAY,
Abstract = Van der Waals complexes of o-benzyne with carbon monoxide and with argon
have been studied ab initio. In both cases `'sandwich'' structures were
found to be more stable than planar structures. From the order of
stability of the planar structures it was concluded that the classical
description of the distorted triple bond in o-benzyne is not fully
valid, and it is believed that one must also consider the biradical
character of the triple bond in o-benzyne.,
DOI = 10.1007/BF01113616,
ISSN = 0040-5744,
Unique-ID = ISI:A1994NP04600005,
V. HROUDA, J. FLORIAN, M. POLASEK, and P. HOBZA, "DOUBLE PROTON-TRANSFER - FROM THE FORMAMIDE DIMER TO THE ADENINE THYMINE
BASE-PAIR," JOURNAL OF PHYSICAL CHEMISTRY, vol. 98, iss. 17, pp. 4742-4747, 1994.
[Bibtex]
@article ISI:A1994NJ53800042,
Author = HROUDA, V and FLORIAN, J and POLASEK, M and HOBZA, P,
Title = DOUBLE PROTON-TRANSFER - FROM THE FORMAMIDE DIMER TO THE ADENINE THYMINE
BASE-PAIR,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1994,
Volume = 98,
Number = 17,
Pages = 4742-4747,
Month = APR 28,
Abstract = The cylic formamide dimer was used as a model system for the
investigation of proton-transfer phenomena in DNA base pairs. The
section of the potential energy surface (PES) in the coordinates of
transferring protons was studied using a wide set of computational
methods, from semiempirical (PM3,MNDO-M) to the ab initio MP2/DZ+2P
level of theory. Three qualitatively different patterns of stationary
points were obtained, depending on the computational method used. The
MP2/DZ+2P calculation resulted in two minima on the PES, corresponding
to the amino-keto and imino-enol tautomeric forms, separated by a
low-lying transition state. The amino-keto tautomer was found to be more
stable than the imino-enol one by 15.6 kcal/mol.,
DOI = 10.1021/j100068a042,
ISSN = 0022-3654,
Unique-ID = ISI:A1994NJ53800042,
P. HOBZA, H. SELZLE, and E. SCHLAG, "POTENTIAL-ENERGY SURFACE OF THE BENZENE DIMER - AH INITIO
THEORETICAL-STUDY," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 116, iss. 8, pp. 3500-3506, 1994.
[Bibtex]
@article ISI:A1994NG88900041,
Author = HOBZA, P and SELZLE, HL and SCHLAG, EW,
Title = POTENTIAL-ENERGY SURFACE OF THE BENZENE DIMER - AH INITIO
THEORETICAL-STUDY,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 1994,
Volume = 116,
Number = 8,
Pages = 3500-3506,
Month = APR 20,
Abstract = The potential energy surface of the benzene dimer was studied by ab
initio methods with inclusion of correlation energy. Three minima of
importance were localized on the surface and a further one at a higher
energy. Surprisingly the most stable structure was found to be the
parallel-displaced structure at all theoretical levels followed by two
T-shaped structures, one normal and one displaced. The normal T-shaped
structure is slightly less stable. The energy barriers among the three
most stable minima are very low, so that all are in dynamic equilibrium.
The experimental intermolecular distance (4.96 Angstrom) determined for
the T-shaped structure agrees nicely with the respective theoretical
value of 5.0 Angstrom. The theoretical stabilization enthalpy (2.3
kcal/mol) supports one of the experimental values based on bulk
properties of benzene (2.4 kcal/mol). The stabilization enthalpy derived
from experimental measurements of appearance potentials (1.6 +/- 0.2
kcal/mol) is slightly below the theoretical value here. The structural
preponderance of the T-shaped and parallel-displaced forms even for
larger systems-and their semiquantitative understanding as
quadrupole-quadrupole interactions-also is seen to carry through to
complex aromatic-aromatic interactions in solid benzene as well as in
the crystalline proteins, showing these interactions to be of generic
importance.,
DOI = 10.1021/ja00087a041,
ISSN = 0002-7863,
Unique-ID = ISI:A1994NG88900041,
T. WRIGHT, V. SPIRKO, and P. HOBZA, "AB-INITIO CALCULATIONS ON AR-NO+ - STRUCTURE AND VIBRATIONAL FREQUENCIES," JOURNAL OF CHEMICAL PHYSICS, vol. 100, iss. 8, pp. 5403-5410, 1994.
[Bibtex]
@article ISI:A1994NF08100001,
Author = WRIGHT, TG and SPIRKO, V and HOBZA, P,
Title = AB-INITIO CALCULATIONS ON AR-NO+ - STRUCTURE AND VIBRATIONAL FREQUENCIES,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1994,
Volume = 100,
Number = 8,
Pages = 5403-5410,
Month = APR 15,
Abstract = The Ar-NO+ ionic complex is studied using ab initio calculations. The
complex geometry and harmonic vibrational frequencies are calculated
using second order Moller-Plesset perturbation theory (MP2)
calculations, employing a variety of basis sets. The calculated
intermolecular bond length supports the experimental value, whereas the
calculated Ar-N-O bond angle suggests a possible reinterpretation of the
experimental result. The vibrational frequencies are then recalculated
using an anharmonic approach and the fundamentals are found to be in
much better agreement with the experimental values [obtained from
zero-kinetic-energy (ZEKE) spectroscopy] than are the harmonic values.
However, the calculations suggest that the potential energy surface of
this complex cation is very anharmonic, and that the experimental
assignment of the vibrational features in the ZEKE spectrum may have to
be revised. The interaction energy of the complex is calculated, both
with and without the full counterpoise (CP) correction; the CP-corrected
values are in much closer agreement with experiment than are the
uncorrected values. The final value of the stabilization energy, taking
into account the MP4 correction is ca. 950 cm-1, in excellent agreement
with the (re-evaluated) experimental value of 920+/-20 cm-1.,
DOI = 10.1063/1.467157,
ISSN = 0021-9606,
Unique-ID = ISI:A1994NF08100001,
J. VACEK, K. KONVICKA, and P. HOBZA, "A MOLECULAR-DYNAMICS STUDY OF THE BENZENE...AR2 COMPLEX - APPLICATION OF
THE NONEMPIRICAL AB-INITIO AND EMPIRICAL LENNARD-JONES 6-12 POTENTIALS," CHEMICAL PHYSICS LETTERS, vol. 220, iss. 1-2, pp. 85-92, 1994.
[Bibtex]
@article ISI:A1994NC82400015,
Author = VACEK, J and KONVICKA, K and HOBZA, P,
Title = A MOLECULAR-DYNAMICS STUDY OF THE BENZENE...AR2 COMPLEX - APPLICATION OF
THE NONEMPIRICAL AB-INITIO AND EMPIRICAL LENNARD-JONES 6-12 POTENTIALS,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1994,
Volume = 220,
Number = 1-2,
Pages = 85-92,
Month = MAR 25,
Abstract = The benzene...Ar2 Cluster was studied by constant energy molecular
dynamics simulations. Three different types of intermolecular potential
were used; two were based on ab initio data, and the third is the
standard empirical 6-12 Lennard-Jones potential. The relative
populations of the (210) and (111) isomers, which are almost constant in
the temperature interval investigated, amount to 63\%:37\%, 60\%:40\%
and 61\%:39\% for the ab initio potentials and Lennard-Jones potential,
respectively. The highest temperature at which the cluster can exist for
a time interval longer than 1 ns is close to 40 K.,
DOI = 10.1016/0009-2614(94)00136-7,
ISSN = 0009-2614,
Unique-ID = ISI:A1994NC82400015,
J. SPONER and P. HOBZA, "NONPLANAR GEOMETRIES OF DNA BASES - AB-INITIO 2ND-ORDER MOLLER-PLESSET
STUDY," JOURNAL OF PHYSICAL CHEMISTRY, vol. 98, iss. 12, pp. 3161-3164, 1994.
[Bibtex]
@article ISI:A1994NC78400019,
Author = SPONER, J and HOBZA, P,
Title = NONPLANAR GEOMETRIES OF DNA BASES - AB-INITIO 2ND-ORDER MOLLER-PLESSET
STUDY,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1994,
Volume = 98,
Number = 12,
Pages = 3161-3164,
Month = MAR 24,
Abstract = Interactions of DNA bases represent a crucial source of DNA
conformational variability. Oligonucleotide crystal studies revealed a
number of base-base interactions which seem to be stabilized by
nonplanar DNA base amino groups. Therefore, an accurate description of
the geometry and deformability of the DNA base amino groups is very
important. Here, the second-order Moller-Plesset (MP2)
6-31G*-optimized nonplanar geometries of adenine, cytosine, guanine,
thymine, and isocytosine are presented. The amino groups of the bases
exhibit significant Sp3 pyramidalization. The dihedral angles between
the cytosine and adenine rings and their amino group hydrogen atoms
range from 10 to 25-degrees, and the nonplanar cytosine and adenine are
0.4 kcal/mol more stable than the planar molecules. Dihedral angles
between the two guanine amino group hydrogen atoms and the guanine ring
are 43 and 12-degrees, and the nonplanar guanine is 1.6 kcal/mol more
stable than the planar molecule. Isocytosine exhibits amino group
properties similar to those of guanine. Selected DNA bases were also
optimized using larger basis sets of atomic orbitals: 6-31G**, DZP+,
and DZ(2d). The MP2/6-31G** calculations yield results very similar
to those of the MP2/6-31G* calculations, while the larger DZP+ and
DZ(2d) basis sets indicate an even greater amino group nonplanarity.,
DOI = 10.1021/j100063a019,
ISSN = 0022-3654,
Unique-ID = ISI:A1994NC78400019,
A. DORIGO, P. SCHLEYER, and P. HOBZA, "THE STRUCTURES OF LINC, NANC, AND KNC - POTENTIAL-ENERGY SURFACE FOR THE
ORBITING MOTION OF THE METAL CATION AROUND THE CN GROUP," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 15, iss. 3, pp. 322-332, 1994.
[Bibtex]
@article ISI:A1994MX62000006,
Author = DORIGO, A and SCHLEYER, PV and HOBZA, P,
Title = THE STRUCTURES OF LINC, NANC, AND KNC - POTENTIAL-ENERGY SURFACE FOR THE
ORBITING MOTION OF THE METAL CATION AROUND THE CN GROUP,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 1994,
Volume = 15,
Number = 3,
Pages = 322-332,
Month = MAR,
Abstract = Sets of XNC (X = Li, Na, and K) structures have been investigated using
a variety of theoretical methods and basis sets. Two linear and a
bridged structure correspond to an energy minimum for LiCN. For NaCN and
KCN, the linear isocyanide is a minimum at most levels of theory but
becomes a second-order stationary point when correlated levels and large
basis sets are used. Two transition structures are involved in the
interconversion of the bridged form and each linear isomer. The
isomerization of the bridged minimum to the linear XCN involves a
substantial barrier in each case, so that the satellite motion of the
metal is facile at one end but not at the other. Calculations with large
basis sets and with electron correlation, fourth-order Moller-Plesset
theory for KNC, and quadratic configuration interaction [QCISD(T)] for
LiNC and NaNC give qualitative and quantitative agreement with this
experiment. The sodium and potassium cyanide prefer bridged forms, in
contrast to the linear isocyanide LiNC. (C) 1994 by John Wiley and Sons,
Inc.,
DOI = 10.1002/jcc.540150307,
ISSN = 0192-8651,
Unique-ID = ISI:A1994MX62000006,
J. FLORIAN, V. HROUDA, and P. HOBZA, "PROTON-TRANSFER IN THE ADENINE-THYMINE BASE-PAIR," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 116, iss. 4, pp. 1457-1460, 1994.
[Bibtex]
@article ISI:A1994MZ28700034,
Author = FLORIAN, J and HROUDA, V and HOBZA, P,
Title = PROTON-TRANSFER IN THE ADENINE-THYMINE BASE-PAIR,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 1994,
Volume = 116,
Number = 4,
Pages = 1457-1460,
Month = FEB 23,
Abstract = The transition state for the double proton transfer in the Watson-Crick
type of adenine-thymine (AT) base pair was located by using the ab
initio HF MINI-1 full gradient optimization technique. Allowing the
geometry to relax in the calculation of the double proton transfer and
interaction energies results in a substantial lowering of the energetic
difference between AT and its imino-enol tautomer, A*T*. An energy
barrier of 9.7 kcal/mol was calculated for the lowest energy reaction
path from the canonical AT structure to the rare tautomeric A*T*
structure, whereas a barrier of only 0.2 kcal/mol occurred for the
reverse reaction. Although the relative energies may be affected by the
theoretical level used, it is evident that there exist two energy minima
which are separated by a low-lying transition state. Our results confirm
the stability of the genetic code. More specifically, the possibility
that proton transfer in the nucleic acid base pairs might be the cause
of spontaneous point mutations in DNA and aging phenomena is not
supported by the SCF/MINI-1 results for the isolated AT base pair. No
minima which correspond to the zwitterionic structures A(+)T(-) and
A(-)T(+) were found. The effect of basis set extension was studied by
including single-point SCF/MIDI-1 calculations. In addition, we suggest
a possible role of the remarkably large interaction enthalpy of the
A*T* base pair formed by imino-enol tautomers in RNA-ribozyme and
codon-anticodon interactions.,
DOI = 10.1021/ja00083a034,
ISSN = 0002-7863,
Unique-ID = ISI:A1994MZ28700034,
L-LYSINE-L-ALANINE-L-ALANINE TRIPEPTIDE WITH 4 MODELS OF B-DNA WITH
DIFFERENT COMPOSITIONS," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 11, iss. 4, pp. 869-880, 1994.
[Bibtex]
@article ISI:A1994MZ78400012,
Author = VONDRASEK, J and SPONAR, J and HOBZA, P,
Title = AN EMPIRICAL POTENTIAL STUDY OF THE INTERACTION OF
L-LYSINE-L-ALANINE-L-ALANINE TRIPEPTIDE WITH 4 MODELS OF B-DNA WITH
DIFFERENT COMPOSITIONS,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1994,
Volume = 11,
Number = 4,
Pages = 869-880,
Month = FEB,
Abstract = The empirical potential including the intra- and intermolecular energy
terms was used to study the interaction of L-Lysine-L-Alanine-L-Alanine
Tripeptide with four models of B-DNA with different compositions. On the
basis of a detailed search of the respective potential energy surface,
it was found that the peptide is preferentially bounded to the AT-rich
sequences. Analysis of the different energy contributions indicated that
the electrostatic term is responsible for this preference. The results
agree with the experimental data on the selectivity of some DNA -
binding proteins and polypeptides to AT - rich DNA.,
ISSN = 0739-1102,
Unique-ID = ISI:A1994MZ78400012,
- AN AB-INITIO QUANTUM-CHEMICAL ANALYSIS," JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM, vol. 110, iss. 1, pp. 35-40, 1994.
[Bibtex]
@article ISI:A1994MT81600005,
Author = SPONER, J and HOBZA, P,
Title = SEQUENCE-DEPENDENT INTRINSIC DEFORMABILITY OF THE DNA-BASE AMINO-GROUPS
- AN AB-INITIO QUANTUM-CHEMICAL ANALYSIS,
Journal = JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM,
Year = 1994,
Volume = 110,
Number = 1,
Pages = 35-40,
Month = JAN 27,
Abstract = An accurate description of the interactions between DNA bases is of
fundamental importance in the theoretical analysis of DNA structure,
flexibility and dynamics. These base-base interactions are significantly
influenced by the properties of the DNA base amino groups. In the
present paper we show that, in constrast to the empirical force fields,
ab initio calculations predict non-planar geometries for the DNA base
amino groups. We compare the amino group non-planarity of cytosine,
adenine, guanine, the guanine amino tautomer, 2-aminoadenine,
5-methylcytosine and the guanine formamidine hydrogen bonded complex, at
the HF/6-31G(NH*2) level of theory. In addition, the geometry of
cytosine is optimized at the MP2/6-31G*, MP2/6-31G(NH*2),
HF/6-31G*, HF/4-21G(NH2*) and HF/6-31G levels of theory to estimate
the role of electron correlation and polarization functions in the amino
group geometry. It is shown that the gradient geometry optimization with
inclusion of electron correlation significantly increases the
non-planarity of the cytosine amino group compared to the HF level of
calculations. The influence of non-planar DNA base amino groups on the
conformational variability of DNA is briefly discussed.,
ISSN = 0166-1280,
Unique-ID = ISI:A1994MT81600005,
J. SPONER and P. HOBZA, "BIFURCATED HYDROGEN-BONDS IN DNA CRYSTAL-STRUCTURES - AN AB-INITIO
QUANTUM-CHEMICAL STUDY," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 116, iss. 2, pp. 709-714, 1994.
[Bibtex]
@article ISI:A1994MV28300036,
Author = SPONER, J and HOBZA, P,
Title = BIFURCATED HYDROGEN-BONDS IN DNA CRYSTAL-STRUCTURES - AN AB-INITIO
QUANTUM-CHEMICAL STUDY,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 1994,
Volume = 116,
Number = 2,
Pages = 709-714,
Month = JAN 26,
Abstract = An ab initio quantum chemical analysis is performed on the intrinsic
deformability of the DNA base amino groups and their role in the base
stacking interactions and conformational variability observed in the DNA
crystal structures. The present calculations, made at the HF/6-31G (NH2)
and MP2/6-31G levels of theory, lead to results qualitatively different
from the previous empirical potential studies and demonstrate limited
applicability of the commonly used force fields. The amino groups of
isolated DNA bases are nonplanar, and the deviation of the amino group
hydrogens from the DNA base plane amounts to 0.1-0.5 angstrom. The
largest amino group nonplanarity is found for guanine. In the case of
cytosine containing complexes, modeling the isolated base pair, the
amino group geometry is determined primarily by the intermolecular
geometry of the hydrogen bonds. The flexibility of the amino groups
facilitates optimization of the interaction energy under condition of
nonplanar geometry of the complex. On the other hand, the DNA base amino
groups are significantly nonplanar, if they participate in the
interstrand bifurcated hydrogen bonds or in the interstrand contacts of
amino groups. Both phenomena are observed in many DNA crystal
structures. The nonplanar amino group geometry improves the interaction
energy. It is demonstrated that the widespread idea of the interstrand
repulsive amino group clashes in the DNA is not correct, because close
contact between two amino groups results in an attractive interaction
similar to that in the bifurcated hydrogen bonds. The only exception
represents the steps having crystallographically identical base pairs.
It is because attractive amino group interaction requires a highly
asymmetric arrangement of the two amino groups, while any geometry with
2-fold symmetry is repulsive. The ab initio calculations are
supplemented by an analysis of the contacts of amino groups in the
available B-DNA crystals to show that the close amino group contacts are
very frequent in the asymmetric steps. These close contacts are,
however, absent in the central steps of the crystal structures with
crystallographically identical strands. This finding agrees with the
nonempirical calculations and shows that conformational variability of
the symmetric steps is significantly restricted by the crystal packing
forces.,
DOI = 10.1021/ja00081a036,
ISSN = 0002-7863,
Unique-ID = ISI:A1994MV28300036,
1993
R. BURCL and P. HOBZA, "AB-INITIO STUDY ON THE METHANOL-WATER CATION-RADICAL POTENTIAL-ENERGY
SURFACE," THEORETICA CHIMICA ACTA, vol. 87, iss. 1-2, pp. 97-105, 1993.
[Bibtex]
@article ISI:A1993MK52500009,
Author = BURCL, R and HOBZA, P,
Title = AB-INITIO STUDY ON THE METHANOL-WATER CATION-RADICAL POTENTIAL-ENERGY
SURFACE,
Journal = THEORETICA CHIMICA ACTA,
Year = 1993,
Volume = 87,
Number = 1-2,
Pages = 97-105,
Month = NOV,
Abstract = Potential energy surface for reaction of CH3OH+. and H2O was
investigated at MP2/3-21G*(O) and MP2/6-31G* levels. Six minima and
four saddle points were localized. The three deepest minima are of
H-bond type while the fourth one possesses the three-electron hemibond.,
DOI = 10.1007/BF01113532,
ISSN = 0040-5744,
Unique-ID = ISI:A1993MK52500009,
R. ZAHRADNIK, P. HOBZA, B. WICHTERLOVA, and J. CEJKA, "ISOMORPHOUS SUBSTITUTION OF SI FOR AL, GA, FE, IN AND B IN
MOLECULAR-SIEVES OF MFI STRUCTURE - A QUANTUM-CHEMICAL, AMMONIA
DESORPTION AND CATALYTIC ACTIVITY STUDY OF FRAMEWORK SI-OH-M ACID SITE
STRENGTH," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 58, iss. 10, pp. 2474-2488, 1993.
[Bibtex]
@article ISI:A1993MJ61000023,
Author = ZAHRADNIK, R and HOBZA, P and WICHTERLOVA, B and CEJKA, J,
Title = ISOMORPHOUS SUBSTITUTION OF SI FOR AL, GA, FE, IN AND B IN
MOLECULAR-SIEVES OF MFI STRUCTURE - A QUANTUM-CHEMICAL, AMMONIA
DESORPTION AND CATALYTIC ACTIVITY STUDY OF FRAMEWORK SI-OH-M ACID SITE
STRENGTH,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1993,
Volume = 58,
Number = 10,
Pages = 2474-2488,
Month = OCT,
Abstract = A theoretical and experimental study of metallosilicates with MFI
structure revealed the order Al > Ga > Fe > In > B in the acid Si-OH-M
framework site strength. Ab initio calculations of the energy and
geometry characteristics in a simple structural unit modelling the
isomorphous substitution were carried out for Al, Ga, In and B as
heteroatoms in silicates. Experimental data on toluene alkylation with
ethylene and temperature-programmed desorption of ammonia allowed to
distinguish the acid site strength of Al-, Fe- and In-silicates, thus,
completing the acidity sequence of metallosilicates synthesized so far.
Moreover, the study confirmed rather short-range effects resulting from
isomorphous substitution of a heteroatom into the molecular sieve
framework.,
DOI = 10.1135/cccc19932474,
ISSN = 0010-0765,
Unique-ID = ISI:A1993MJ61000023,
P. HOBZA, H. SELZLE, and E. SCHLAG, "PROPERTIES OF FLUOROBENZENE ... AR AND P-DIFLUOROBENZENE ... AR
COMPLEXES - AB-INITIO STUDY," JOURNAL OF CHEMICAL PHYSICS, vol. 99, iss. 4, pp. 2809-2811, 1993.
[Bibtex]
@article ISI:A1993LR05600053,
Author = HOBZA, P and SELZLE, HL and SCHLAG, EW,
Title = PROPERTIES OF FLUOROBENZENE ... AR AND P-DIFLUOROBENZENE ... AR
COMPLEXES - AB-INITIO STUDY,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1993,
Volume = 99,
Number = 4,
Pages = 2809-2811,
Month = AUG 15,
Abstract = The potential energy surfaces of fluorobenzene ... Ar and
p-difluorobenzene ... Ar were studied by ab initio calculations with
inclusion of second-order Moller-Plesset correlation energy. The optimal
structures of both complexes agree nicely with experimental data. The
theoretical stabilization enthalpy for the second complex (294 cm-1)
agrees well with the experimental data (190-242 cm-1). The fluorine
substitution of the benzene molecule does not influence the
characteristics of the respective complex. The dipole moment of both
complexes was calculated; in both cases the electron transfer from
fluorobenzene to Ar was found.,
DOI = 10.1063/1.465189,
ISSN = 0021-9606,
Unique-ID = ISI:A1993LR05600053,
P. HOBZA and R. ZAHRADNIK, "WORLD OF VAN-DER-WAALS SPECIES," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 58, iss. 7, pp. 1465-1475, 1993.
[Bibtex]
@article ISI:A1993LU96700001,
Author = HOBZA, P and ZAHRADNIK, R,
Title = WORLD OF VAN-DER-WAALS SPECIES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1993,
Volume = 58,
Number = 7,
Pages = 1465-1475,
Month = JUL,
Abstract = Van der Waals species (molecules, ions, radicals) attract the attention
of chemists, chemical physicists and molecular biologists. Study of
these systems presents a real challenge for both experimentalists and
theorists. The main features of the contemporary possibilities for
quantum chemical treatment are illustrated mostly on systems studied in
the authors' laboratory. Prospects in the area are briefly outlined.,
DOI = 10.1135/cccc19931465,
ISSN = 0010-0765,
Unique-ID = ISI:A1993LU96700001,
P. HOBZA, R. ZAHRADNIK, and D. SMITH, "REACTIONS BETWEEN H-3+ AND RARE-GAS ATOMS," CHEMICAL PHYSICS LETTERS, vol. 208, iss. 5-6, pp. 497-502, 1993.
[Bibtex]
@article ISI:A1993LH43900024,
Author = HOBZA, P and ZAHRADNIK, R and SMITH, D,
Title = REACTIONS BETWEEN H-3+ AND RARE-GAS ATOMS,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1993,
Volume = 208,
Number = 5-6,
Pages = 497-502,
Month = JUN 18,
Abstract = Quantum chemical calculations have been carried out for the reactions
between H-3+ and rare ps atoms X (X = He, Ne, Ar, Kr). These reactions,
which lead to protonated rare ps atoms, are all endoergic. This means
that protonated rare gas atoms are stronger acids than H-3+. The
reactions proceed via complexes of the H-3+.X type. While H-3+.He is
hardly stable, H-3+.Ar and H-3+. Kr are quite stable. Three equivalent
minima of H-3+.X (C2v symmetry structure in which X aims at the H atoms
in the H-3+ triangle) are separated by three saddle points (also C2v
symmetry; X aims at the middle of the H-H bond). The calculated barrier
height is negligible for the He and Ne complexes and amounts to 4.3 and
8.1 kcal/mol for the isomerization of H-3+.Ar and H-3+. Kr,
respectively. Satisfactory agreement is found between the calculated and
experimentally derived properties.,
DOI = 10.1016/0009-2614(93)87179-7,
ISSN = 0009-2614,
Unique-ID = ISI:A1993LH43900024,
P. HOBZA, H. SELZLE, and E. SCHLAG, "NEW STRUCTURE FOR THE MOST STABLE ISOMER OF THE BENZENE DIMER - A
QUANTUM-CHEMICAL STUDY," JOURNAL OF PHYSICAL CHEMISTRY, vol. 97, iss. 16, pp. 3937-3938, 1993.
[Bibtex]
@article ISI:A1993KY46600002,
Author = HOBZA, P and SELZLE, HL and SCHLAG, EW,
Title = NEW STRUCTURE FOR THE MOST STABLE ISOMER OF THE BENZENE DIMER - A
QUANTUM-CHEMICAL STUDY,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1993,
Volume = 97,
Number = 16,
Pages = 3937-3938,
Month = APR 22,
Abstract = New and surprising ab initio calculations suggest that the potential
curve between two benzene molecules is more complicated than hitherto
assumed. In fact, the calculations propose two minima on the potential
energy surface of the benzene dimer. The most stable one is found to be
the parallel-displaced structure so that the T-shaped structure is now
found to be at slightly higher energy. The intermolecular distance found
for the T-shaped structure agrees nicely with that predicted from new
experiments.,
DOI = 10.1021/j100118a002,
ISSN = 0022-3654,
Unique-ID = ISI:A1993KY46600002,
P. HOBZA, O. BLUDSKY, H. SELZLE, and E. SCHLAG, "GROUND-STATE POTENTIAL SURFACE FOR VANDERWAALS COMPLEXES - ABINITIO
2ND-ORDER MOLLER-PLESSET STUDY ON BENZENE...N-2 VANDERWAALS MOLECULE," JOURNAL OF CHEMICAL PHYSICS, vol. 98, iss. 8, pp. 6223-6226, 1993.
[Bibtex]
@article ISI:A1993KX94600022,
Author = HOBZA, P and BLUDSKY, O and SELZLE, HL and SCHLAG, EW,
Title = GROUND-STATE POTENTIAL SURFACE FOR VANDERWAALS COMPLEXES - ABINITIO
2ND-ORDER MOLLER-PLESSET STUDY ON BENZENE...N-2 VANDERWAALS MOLECULE,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1993,
Volume = 98,
Number = 8,
Pages = 6223-6226,
Month = APR 15,
Abstract = The potential energy surface of the benzene...N2 was investigated ab
initio using second-order Moller-Plesset (MP2) theory. The calculations
were performed with 6-31 + G*/[5s4p2d] and 6-31 + G*/[5s4p3d]
basis sets. Among five structures studied the sandwich structure (N2
lies in the plane parallel to the benzene ring) appeared to be most
stable. The calculated intermolecular distance (3.46 angstrom after
vibrational averaging) is in excellent agreement with recent high
resolution measurements. Calculated stabilization energy (591 cm-1) and
intermolecular vibrational frequencies (stretching, 57 cm-1; torsion, 73
cm-1) are compared with available experimental results.,
DOI = 10.1063/1.464815,
ISSN = 0021-9606,
Unique-ID = ISI:A1993KX94600022,
V. HROUDA, J. FLORIAN, and P. HOBZA, "STRUCTURE, ENERGETICS, AND HARMONIC VIBRATIONAL-SPECTRA OF THE
ADENINE-THYMINE AND ADENINE-ASTERISK-THYMINE-ASTERISK BASE-PAIRS -
GRADIENT NONEMPIRICAL AND SEMIEMPIRICAL STUDY," JOURNAL OF PHYSICAL CHEMISTRY, vol. 97, iss. 8, pp. 1542-1557, 1993.
[Bibtex]
@article ISI:A1993KP60300015,
Author = HROUDA, V and FLORIAN, J and HOBZA, P,
Title = STRUCTURE, ENERGETICS, AND HARMONIC VIBRATIONAL-SPECTRA OF THE
ADENINE-THYMINE AND ADENINE-ASTERISK-THYMINE-ASTERISK BASE-PAIRS -
GRADIENT NONEMPIRICAL AND SEMIEMPIRICAL STUDY,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1993,
Volume = 97,
Number = 8,
Pages = 1542-1557,
Month = FEB 25,
Abstract = The structure, interaction energies, and harmonic vibrational spectra of
adenine-thymine and adenine*-thymine* (imino-enol tautomers) base
pairs were studied by the ab initio and semiempirical methods. Gradient
optimization at the SCF/MINI-1 level has shown that the former complex
is only about 10 kcal/mol more stable than the latter. We have
demonstrated that single-point calculations with a larger basis set
performed for the reference geometry optimized in the minimal basis set
(SCF/MIDI-1//SCF/MINI-1) and those taking the correlation energy into
account can lead to unrealistic interaction energy values. Hence,
single-point calculations of this kind should be taken with great care
for AT and A*T* complexes. The results obtained by the semiempirical
PM3 method agree reasonably well with the ab initio values; this is not
true of the AM1 method. In addition to the interaction energy,
reorganization energy and basis set superposition error were also
determined; both the latter terms (which are positive) are important and
should not be neglected. The theoretical interaction enthalpy of the AT
formation agrees fairly well with the corresponding experimental value.
Knowledge of the harmonic vibrational spectra of isolated A, T, A*,
and T* bases and the AT and A*T* base pairs enabled us to
determine the frequency and intensity changes induced by the
Watson-Crick type of hydrogen bonding, tautomeric transitions, and
double proton transfer in the AT base pair.,
DOI = 10.1021/j100110a015,
ISSN = 0022-3654,
Unique-ID = ISI:A1993KP60300015,
L. CESPIVA, V. BONACICKOUTECKY, J. KOUTECKY, P. JENSEN, V. HROUDA, P. CARSKY, V. SPIRKO, and P. HOBZA, "ABINITIO CALCULATIONS OF THE ROTATION-VIBRATION SPECTRUM OF NA-3(+)," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 58, iss. 1, pp. 24-28, 1993.
[Bibtex]
@article ISI:A1993KU01700003,
Author = CESPIVA, L and BONACICKOUTECKY, V and KOUTECKY, J and JENSEN, P and
HROUDA, V and CARSKY, P and SPIRKO, V and HOBZA, P,
Title = ABINITIO CALCULATIONS OF THE ROTATION-VIBRATION SPECTRUM OF NA-3(+),
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1993,
Volume = 58,
Number = 1,
Pages = 24-28,
Month = JAN,
Abstract = SCF, 6C-SCF, MP4 and valence-electron full CI calculations were
performed in order to determine the potential surface of Na3+. A power
series in the variables y(i) = 1-exp(-aDELTAr(i)), where DELTAr(i) arc
bond length displacements from equilibrium, has been fitted through the
surface obtained and used in a variational rotation-vibration
calculation with a basis set of products of Morse-oscillator
eigenfunctions and symmetric top rotational wave functions. In contrast
to H-3+, Na3+ behaves as a very rigid molecule and docs not exhibit any
anomalous anharmonicity. With our best potential surface, MP4, the
predicted E' and A1' fundamental frequencies are 105.1 and 146.7 cm-1,
and the harmonic E' and A1' frequencies are 106.5 and 148.3 cm-1.,
DOI = 10.1135/cccc19930024,
ISSN = 0010-0765,
Unique-ID = ISI:A1993KU01700003,
1992
VANDERWAALS SPECIES," BERICHTE DER BUNSEN-GESELLSCHAFT-PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 96, iss. 9, pp. 1294-1298, 1992.
[Bibtex]
@article ISI:A1992JX36200043,
Author = HOBZA, P and ZAHRADNIK, R,
Title = ASSOCIATES, CLUSTERS, INTERMOLECULAR COMPLEXES, SUPRAMOLECULAR SYSTEMS -
VANDERWAALS SPECIES,
Journal = BERICHTE DER BUNSEN-GESELLSCHAFT-PHYSICAL CHEMISTRY CHEMICAL PHYSICS,
Year = 1992,
Volume = 96,
Number = 9,
Pages = 1294-1298,
Month = SEP,
Note = DISCUSSION MEETING OF THE
DEUTSCHE-BUNSEN-GESELLSCHAFT-FUR-PHYSIKALISCHE-CHEMIE : REACTIONS IN AND
WITH CLUSTERS, SCHLIERSEE, GERMANY, MAR 29-APR 01, 1992,
Organization = DEUT BUNSEN GESELL PHYS CHEM,
Abstract = This is an article summarizing theoretical studies carried out recently
in our laboratory on van der Waals (vdW) species. In contrast to
classical molecules, theoretical structure elucidation of vdW molecules
nearly always represents a challenge for computational chemists. Results
on molecule-molecule complexes (e.g., (H2)2, benzene and benzyne
complexes with rare gas atoms, benzene dimer, purine-pyrimidine
complexes) and ion-molecule complexes (e. g., H4+., radical cations of
dimers of alkyl halogenides and of alkylated and arylated water) are
reviewed. The importance of study of the intersystem vibrational degrees
and the role of molecular dynamics in the field of vdW systems in
outlined.,
ISSN = 0005-9021,
Unique-ID = ISI:A1992JX36200043,
O. BLUDSKY, V. SPIRKO, V. HROUDA, and P. HOBZA, "VIBRATIONAL DYNAMICS OF THE BENZENE...ARGON COMPLEX," CHEMICAL PHYSICS LETTERS, vol. 196, iss. 5, pp. 410-416, 1992.
[Bibtex]
@article ISI:A1992JH69200003,
Author = BLUDSKY, O and SPIRKO, V and HROUDA, V and HOBZA, P,
Title = VIBRATIONAL DYNAMICS OF THE BENZENE...ARGON COMPLEX,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1992,
Volume = 196,
Number = 5,
Pages = 410-416,
Month = AUG 21,
Abstract = A section of the potential energy surface of the benzene...argon complex
corresponding to the argon versus benzene intermolecular vibrational
modes has been determined by fitting the existing ab initio data with
the use of two different empirical potentials. From these potential
energy sections, using an approximate vibrational Hamiltonian, the
intermolecular vibrational energy levels have been evaluated and
compared with available spectral and previous theoretical data for
C6H6...Ar-40. The stretching fundamental frequency has been found to be
in excellent agreement with the literature data. The bending (nearly
degenerate) frequencies, however, have been predicted to be
significantly higher than those from literature. A reassignment of the
observed absorption based on our predictions has led to a complete
agreement between theory and experiment. We feel that this casts doubt
on the previous vibrational assignment of the observed transitions.,
DOI = 10.1016/0009-2614(92)85712-J,
ISSN = 0009-2614,
Unique-ID = ISI:A1992JH69200003,
P. HOBZA, O. BLUDSKY, H. SELZLE, and E. SCHLAG, "ABINITIO 2ND-ORDER AND 4TH-ORDER MOLLER-PLESSET STUDY ON STRUCTURE,
STABILIZATION ENERGY, AND STRETCHING VIBRATION OF BENZENE...X
(X=HE,NE,AR,KR,XE) VANDERWAALS MOLECULES," JOURNAL OF CHEMICAL PHYSICS, vol. 97, iss. 1, pp. 335-340, 1992.
[Bibtex]
@article ISI:A1992JA79200040,
Author = HOBZA, P and BLUDSKY, O and SELZLE, HL and SCHLAG, EW,
Title = ABINITIO 2ND-ORDER AND 4TH-ORDER MOLLER-PLESSET STUDY ON STRUCTURE,
STABILIZATION ENERGY, AND STRETCHING VIBRATION OF BENZENE...X
(X=HE,NE,AR,KR,XE) VANDERWAALS MOLECULES,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1992,
Volume = 97,
Number = 1,
Pages = 335-340,
Month = JUL 1,
Abstract = The C6v structure of benzene...X (X = He, Ne, Ar, Kr, Xe) complexes was
investigated with second-order Moller-Plesset (MP2) theory; for the
benzene ... He the whole potential-energy surface (PES) was also
studied. The stabilization energy of the benzene ... He was also
determined at the fourth-order Moller-Plesset (MP4) level; the
respective MP4 stabilization energy is almost identical with MP2
stabilization energy which is due to the compensation of MP3 and MP4
contributions. The ab initio MP2 intermolecular distances agree nicely
for all the complexes studied with the experimental value. While the
stabilization energy of benzene...He and benzene...Ne (67 cm-1; 99 cm-1)
is considerably smaller than that of benzene...Ar (429 cm-1), the
intersystem distance differs less (3.32 angstrom, 3.50 angstrom, 3.53
angstrom). The stabilization energies and intersystem distances for
benzene...Kr and benzene...Xe are 485 and 601 cm-1 and 3.71 and 3.89
angstrom, respectively. The PES of benzene...He differs from that of
benzene...Ar and can be characterized as more isotropic. The harmonic
and anharmonic stretching frequencies were determined for all the
complexes; anharmonicity plays a crucial role only for the benzene...He
complex. Theoretical and experimental stretching frequencies for
benzene...Ar and benzene...Kr agree very well.,
DOI = 10.1063/1.463578,
ISSN = 0021-9606,
Unique-ID = ISI:A1992JA79200040,
OBTAINABLE FROM ABINITIO CALCULATIONS," CROATICA CHEMICA ACTA, vol. 65, iss. 1, pp. 11-15, 1992.
[Bibtex]
@article ISI:A1992JF19500004,
Author = HOBZA, P,
Title = ON THE DIFFERENT CHARACTERISTICS OF MEDIUM-SIZED VANDERWAALS MOLECULES
OBTAINABLE FROM ABINITIO CALCULATIONS,
Journal = CROATICA CHEMICA ACTA,
Year = 1992,
Volume = 65,
Number = 1,
Pages = 11-15,
Month = JUN 15,
Abstract = Nonempirical ab initio calculations with inclusion of the correlation
energy are used to generate, directly or indirectly (via an analytical
form of the potential-energy surface), various properties of
medium-sized van der Waals molecules. As shown for benzene...Ar and the
benzene dimer, the calculated characteristics agree with the
experimental results. If the experimental values are lacking or if they
are uncertain, the theoretical characteristics can be used with
confidence.,
ISSN = 0011-1643,
Unique-ID = ISI:A1992JF19500004,
P. HOBZA, H. SELZLE, and E. SCHLAG, "HIGH-LEVEL ABINITIO CALCULATIONS ON ACETYLENE DIMER - A PROTOTYPE FOR
ESTIMATION OF THE ACCURACY OF THE BENZENE DIMER STABILIZATION ENERGY," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 57, iss. 6, pp. 1186-1190, 1992.
[Bibtex]
@article ISI:A1992JG39300004,
Author = HOBZA, P and SELZLE, HL and SCHLAG, EW,
Title = HIGH-LEVEL ABINITIO CALCULATIONS ON ACETYLENE DIMER - A PROTOTYPE FOR
ESTIMATION OF THE ACCURACY OF THE BENZENE DIMER STABILIZATION ENERGY,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1992,
Volume = 57,
Number = 6,
Pages = 1186-1190,
Month = JUN,
Abstract = High level ab initio calculations (up to MP4/DZ + (2df, 2p)) on
acetylene dimer permit the evaluation of a highly accurate stabilization
energy of the dimer (5.9 kJ/mol) and hence serves as a test case for the
error limit for lower level calculations. This error limit was employed
to estimate the stabilization energy and enthalpy in the benzene dimer
calculation. From this the theoretical value of formation enthalpy at 0
K (11.3 kJ/mol) is obtained which is larger than the corresponding
experimental value (6.7 +/- 2.1 kJ/mol).,
DOI = 10.1135/cccc19921186,
ISSN = 0010-0765,
Unique-ID = ISI:A1992JG39300004,
P. HOBZA and R. ZAHRADNIK, "AN ESSAY ON THE THEORY AND CALCULATIONS OF INTERMOLECULAR INTERACTIONS," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 42, iss. 4, pp. 581-590, 1992.
[Bibtex]
@article ISI:A1992HL97700004,
Author = HOBZA, P and ZAHRADNIK, R,
Title = AN ESSAY ON THE THEORY AND CALCULATIONS OF INTERMOLECULAR INTERACTIONS,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1992,
Volume = 42,
Number = 4,
Pages = 581-590,
Month = MAY 20,
DOI = 10.1002/qua.560420407,
ISSN = 0020-7608,
Unique-ID = ISI:A1992HL97700004,
1991
P. HOBZA, H. SELZLE, and E. SCHLAG, "ABINITIO CALCULATIONS ON THE STRUCTURE, STABILIZATION, AND DIPOLE-MOMENT
OF BENZENE ... AR COMPLEX," JOURNAL OF CHEMICAL PHYSICS, vol. 95, iss. 1, pp. 391-394, 1991.
[Bibtex]
@article ISI:A1991FT84700039,
Author = HOBZA, P and SELZLE, HL and SCHLAG, EW,
Title = ABINITIO CALCULATIONS ON THE STRUCTURE, STABILIZATION, AND DIPOLE-MOMENT
OF BENZENE ... AR COMPLEX,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1991,
Volume = 95,
Number = 1,
Pages = 391-394,
Month = JUL 1,
Abstract = The potential energy surface (PES) of the benzene... Ar complex was
investigated ab initio using the second-order Moller-Plesset theory
demonstrating the practical use of such calculations for these
complexes. Among five structures studied, the highest symmetry
C6-upsilon structure for the Ar appeared to be most stable
(stabilization energy: 429 cm-1; distance of molecular centers: 3.526
angstrom). The PES is much more isotropic than was found in previous
papers using an empirical potential. The calculated intermolecular
distance is in excellent agreement with recent high resolution
measurements-also the dipole moment is in excellent agreement with known
data.,
DOI = 10.1063/1.461440,
ISSN = 0021-9606,
Unique-ID = ISI:A1991FT84700039,
P. HOBZA, D. NACHTIGALLOVA, Z. HAVLAS, P. MALON, and J. SPONAR, "INTERACTION OF LYSINE-ALANINE-ALANINE TRIPEPTIDE WITH A FRAGMENT OF DNA
- AN EMPIRICAL POTENTIAL STUDY," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 12, iss. 1, pp. 9-16, 1991.
[Bibtex]
@article ISI:A1991EQ52200002,
Author = HOBZA, P and NACHTIGALLOVA, D and HAVLAS, Z and MALON, P and SPONAR, J,
Title = INTERACTION OF LYSINE-ALANINE-ALANINE TRIPEPTIDE WITH A FRAGMENT OF DNA
- AN EMPIRICAL POTENTIAL STUDY,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 1991,
Volume = 12,
Number = 1,
Pages = 9-16,
Month = JAN-FEB,
Abstract = Interaction of a rigid fragment of B-DNA (polyanionic as well as
screened by Na+ cations) with the flexible tripeptide Lys-Ala-Ala (in
both L and D configurations) were investigated with the aid of an
empirical potential. The potential consists of intramolecular (MM2
potential) and intermolecular (pair potential described in reference 1)
parts; hence total energy is formed by intra- and intermolecular
components. The results demonstrate that intramolecular relaxation of
the peptide results in a considerable decrease in total energy. While
energies of DNA complexes with L-Lys-L-Ala-L-Ala were comparable to
those with D-Lys-D-Ala-D-Ala the respective geometries exhibit
considerable differences.,
DOI = 10.1002/jcc.540120103,
ISSN = 0192-8651,
Unique-ID = ISI:A1991EQ52200002,
1990
P. HOBZA, H. SELZLE, and E. SCHLAG, "FLOPPY STRUCTURE OF THE BENZENE DIMER - ABINITIO CALCULATION ON THE
STRUCTURE AND DIPOLE-MOMENT," JOURNAL OF CHEMICAL PHYSICS, vol. 93, iss. 8, pp. 5893-5897, 1990.
[Bibtex]
@article ISI:A1990EE24800061,
Author = HOBZA, P and SELZLE, HL and SCHLAG, EW,
Title = FLOPPY STRUCTURE OF THE BENZENE DIMER - ABINITIO CALCULATION ON THE
STRUCTURE AND DIPOLE-MOMENT,
Journal = JOURNAL OF CHEMICAL PHYSICS,
Year = 1990,
Volume = 93,
Number = 8,
Pages = 5893-5897,
Month = OCT 15,
DOI = 10.1063/1.459587,
ISSN = 0021-9606,
Unique-ID = ISI:A1990EE24800061,
A. SANNIGRAHI, T. KAR, B. NIYOGI, P. HOBZA, and P. SCHLEYER, "THE LITHIUM BOND REEXAMINED," CHEMICAL REVIEWS, vol. 90, iss. 6, pp. 1061-1076, 1990.
[Bibtex]
@article ISI:A1990EC98100007,
Author = SANNIGRAHI, AB and KAR, T and NIYOGI, BG and HOBZA, P and SCHLEYER, PV,
Title = THE LITHIUM BOND REEXAMINED,
Journal = CHEMICAL REVIEWS,
Year = 1990,
Volume = 90,
Number = 6,
Pages = 1061-1076,
Month = SEP-OCT,
DOI = 10.1021/cr00104a007,
ISSN = 0009-2665,
Unique-ID = ISI:A1990EC98100007,
I. STIBOR, P. HOLY, P. HOBZA, and P. CARSKY, "MM2 STUDY OF 20-HYDROXY-4,7,13,16-TETRAOXA-1,10-DIAZABICYCLO [8,8,3]
HENEICOSANE AND ITS FORMATION CONTROLLED BY HYDROGEN-BONDING," JOURNAL OF COMPUTATIONAL CHEMISTRY, vol. 11, iss. 7, pp. 837-847, 1990.
[Bibtex]
@article ISI:A1990DP68400006,
Author = STIBOR, I and HOLY, P and HOBZA, P and CARSKY, P,
Title = MM2 STUDY OF 20-HYDROXY-4,7,13,16-TETRAOXA-1,10-DIAZABICYCLO [8,8,3]
HENEICOSANE AND ITS FORMATION CONTROLLED BY HYDROGEN-BONDING,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 1990,
Volume = 11,
Number = 7,
Pages = 837-847,
Month = AUG,
DOI = 10.1002/jcc.540110707,
ISSN = 0192-8651,
Unique-ID = ISI:A1990DP68400006,
INTRODUCTORY-REMARKS, ISOMERIZATIONS, AND INVERSION BARRIERS OF THE AH2,
AH3, AH4 AND RELATED SYSTEMS," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 55, iss. 4, pp. 869-889, 1990.
[Bibtex]
@article ISI:A1990DC79800001,
Author = ZAHRADNIK, R and HAVLAS, Z and HESS, BA and HOBZA, P,
Title = PROPERTIES AND REACTIVITY OF 1ST AND 2ND ROW HYDRIDES -
INTRODUCTORY-REMARKS, ISOMERIZATIONS, AND INVERSION BARRIERS OF THE AH2,
AH3, AH4 AND RELATED SYSTEMS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1990,
Volume = 55,
Number = 4,
Pages = 869-889,
Month = APR,
ISSN = 0010-0765,
Unique-ID = ISI:A1990DC79800001,
[Bibtex]
@article ISI:A1990CX94400022,
Author = HOBZA, P,
Title = CORRECTION,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1990,
Volume = 167,
Number = 4,
Pages = 378,
Month = MAR 30,
ISSN = 0009-2614,
Unique-ID = ISI:A1990CX94400022,
1989
[Bibtex]
@article ISI:A1989CB67400029,
Author = HOFMANN, HJ and HOBZA, P and CAMMI, R and TOMASI, J and ZAHRADNIK, R,
Title = METAL-ION INTERACTIONS WITH WATER AND AMMONIA,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1989,
Volume = 60,
Pages = 339-350,
Month = NOV,
ISSN = 0166-1280,
Unique-ID = ISI:A1989CB67400029,
P. HOBZA and Z. HAVLAS, "AN EMPIRICAL POTENTIAL FOR INTERACTIONS OF LARGE MOLECULES - APPLICATION
TO BINDING OF DIPEPTIDES TO DNA," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 36, iss. 3, pp. 287-298, 1989.
[Bibtex]
@article ISI:A1989AN61400011,
Author = HOBZA, P and HAVLAS, Z,
Title = AN EMPIRICAL POTENTIAL FOR INTERACTIONS OF LARGE MOLECULES - APPLICATION
TO BINDING OF DIPEPTIDES TO DNA,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1989,
Volume = 36,
Number = 3,
Pages = 287-298,
Month = SEP,
DOI = 10.1002/qua.560360312,
ISSN = 0020-7608,
Unique-ID = ISI:A1989AN61400011,
1988
ACETYLENE BENZENE ASSOCIATES," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 53, iss. 11A, pp. 2495-2502, 1988.
[Bibtex]
@article ISI:A1988R715900003,
Author = PETRUSOVA, H and HAVLAS, Z and HOBZA, P and ZAHRADNIK, R,
Title = A THEORETICAL-STUDY ON ACETYLENE DIMER, ACETYLENE-S-TETRAZINE AND
ACETYLENE BENZENE ASSOCIATES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1988,
Volume = 53,
Number = 11A,
Pages = 2495-2502,
Month = NOV,
ISSN = 0010-0765,
Unique-ID = ISI:A1988R715900003,
OF THE ELECTROSTATIC INTERACTION BETWEEN DNA BASES," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 48, pp. 177-184, 1988.
[Bibtex]
@article ISI:A1988R434100015,
Author = SZCZESNIAK, MM and SCHEINER, S and HOBZA, P,
Title = EFFECTS OF ELECTRON CORRELATION UPON MOLECULAR-INTERACTIONS - CORRECTION
OF THE ELECTROSTATIC INTERACTION BETWEEN DNA BASES,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1988,
Volume = 48,
Pages = 177-184,
Month = OCT,
ISSN = 0166-1280,
Unique-ID = ISI:A1988R434100015,
[Bibtex]
@article ISI:A1988Q980300007,
Author = HOBZA, P and SCHLEYER, PV,
Title = ON THE NATURE OF THE BONDING IN HE-BE-O, NE-BE-O, AR-BE-O MOLECULES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1988,
Volume = 53,
Number = 10,
Pages = 2230-2238,
Month = OCT,
ISSN = 0010-0765,
Unique-ID = ISI:A1988Q980300007,
P. HOBZA and R. ZAHRADNIK, "INTERMOLECULAR INTERACTIONS BETWEEN MEDIUM-SIZED SYSTEMS - NONEMPIRICAL
AND EMPIRICAL CALCULATIONS OF INTERACTION ENERGIES - SUCCESSES AND
FAILURES," CHEMICAL REVIEWS, vol. 88, iss. 6, pp. 871-897, 1988.
[Bibtex]
@article ISI:A1988Q393600005,
Author = HOBZA, P and ZAHRADNIK, R,
Title = INTERMOLECULAR INTERACTIONS BETWEEN MEDIUM-SIZED SYSTEMS - NONEMPIRICAL
AND EMPIRICAL CALCULATIONS OF INTERACTION ENERGIES - SUCCESSES AND
FAILURES,
Journal = CHEMICAL REVIEWS,
Year = 1988,
Volume = 88,
Number = 6,
Pages = 871-897,
Month = SEP-OCT,
DOI = 10.1021/cr00088a004,
ISSN = 0009-2665,
Unique-ID = ISI:A1988Q393600005,
THE METHYLATION OF GUANINE," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 53, iss. 9, pp. 1943-1945, 1988.
[Bibtex]
@article ISI:A1988Q415300007,
Author = HOBZA, P and SANDORFY, C,
Title = ON THE CHANGE OF THE ORDER OF STABILITY OF DNA-BASE PAIRS AS A RESULT OF
THE METHYLATION OF GUANINE,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1988,
Volume = 53,
Number = 9,
Pages = 1943-1945,
Month = SEP,
ISSN = 0010-0765,
Unique-ID = ISI:A1988Q415300007,
B. SCHNEIDER, P. HOBZA, and R. ZAHRADNIK, "POTENTIAL-ENERGY SURFACE OF THE (H-2)2 DIMER - AN MP2 STUDY," THEORETICA CHIMICA ACTA, vol. 73, iss. 2-3, pp. 201-206, 1988.
[Bibtex]
@article ISI:A1988M320300009,
Author = SCHNEIDER, B and HOBZA, P and ZAHRADNIK, R,
Title = POTENTIAL-ENERGY SURFACE OF THE (H-2)2 DIMER - AN MP2 STUDY,
Journal = THEORETICA CHIMICA ACTA,
Year = 1988,
Volume = 73,
Number = 2-3,
Pages = 201-206,
Month = FEB-MAR,
DOI = 10.1007/BF00528204,
ISSN = 0040-5744,
Unique-ID = ISI:A1988M320300009,
R. ZAHRADNIK and P. HOBZA, "ON THE ROLE OF VANDERWAALS INTERACTIONS IN ORGANIC-CHEMISTRY," PURE AND APPLIED CHEMISTRY, vol. 60, iss. 2, pp. 245-252, 1988.
[Bibtex]
@article ISI:A1988M254600014,
Author = ZAHRADNIK, R and HOBZA, P,
Title = ON THE ROLE OF VANDERWAALS INTERACTIONS IN ORGANIC-CHEMISTRY,
Journal = PURE AND APPLIED CHEMISTRY,
Year = 1988,
Volume = 60,
Number = 2,
Pages = 245-252,
Month = FEB,
DOI = 10.1351/pac198860020245,
ISSN = 0033-4545,
Unique-ID = ISI:A1988M254600014,
1987
SCHIFF-BASES," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 37, iss. 3-4, pp. 231-240, 1987.
[Bibtex]
@article ISI:A1987J495200004,
Author = FOUCRAULT, M and HOBZA, P and SANDORFY, C,
Title = QUANTUM CHEMICAL STUDY OF THE SITE OF PROTONATION IN CONJUGATED
SCHIFF-BASES,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1987,
Volume = 37,
Number = 3-4,
Pages = 231-240,
Month = JUL,
ISSN = 0166-1280,
Unique-ID = ISI:A1987J495200004,
PARA-BENZOQUINONE HYDROQUINONE, PYRIDINE PYRROLE AND PYRIDINE PHENOL
COMPLEXES," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 37, iss. 1-2, pp. 11-18, 1987.
[Bibtex]
@article ISI:A1987H927100002,
Author = FOUCRAULT, M and HOBZA, P and SANDORFY, C,
Title = NONEMPIRICAL CALCULATIONS ON HYDROGEN-BONDED AND STACKED STRUCTURES OF
PARA-BENZOQUINONE HYDROQUINONE, PYRIDINE PYRROLE AND PYRIDINE PHENOL
COMPLEXES,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1987,
Volume = 37,
Number = 1-2,
Pages = 11-18,
Month = JUN,
ISSN = 0166-1280,
Unique-ID = ISI:A1987H927100002,
J. SAUER, P. HOBZA, P. CARSKY, and R. ZAHRADNIK, "APPLICABILITY OF THE SUPERMOLECULE MP2 APPROACH TO INTERMOLECULAR
INTERACTIONS - HE-2 AND NE-2," CHEMICAL PHYSICS LETTERS, vol. 134, iss. 6, pp. 553-559, 1987.
[Bibtex]
@article ISI:A1987G946200011,
Author = SAUER, J and HOBZA, P and CARSKY, P and ZAHRADNIK, R,
Title = APPLICABILITY OF THE SUPERMOLECULE MP2 APPROACH TO INTERMOLECULAR
INTERACTIONS - HE-2 AND NE-2,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1987,
Volume = 134,
Number = 6,
Pages = 553-559,
Month = MAR 20,
DOI = 10.1016/0009-2614(87)87192-0,
ISSN = 0009-2614,
Unique-ID = ISI:A1987G946200011,
P. HOBZA, B. SCHNEIDER, J. SAUER, P. CARSKY, and R. ZAHRADNIK, "MP4 INTERACTION ENERGIES AND BASIS SET SUPERPOSITION ERRORS FOR THE
(H-2)2 DIMER," CHEMICAL PHYSICS LETTERS, vol. 134, iss. 5, pp. 418-422, 1987.
[Bibtex]
@article ISI:A1987G806800006,
Author = HOBZA, P and SCHNEIDER, B and SAUER, J and CARSKY, P and ZAHRADNIK, R,
Title = MP4 INTERACTION ENERGIES AND BASIS SET SUPERPOSITION ERRORS FOR THE
(H-2)2 DIMER,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1987,
Volume = 134,
Number = 5,
Pages = 418-422,
Month = MAR 13,
DOI = 10.1016/0009-2614(87)87165-8,
ISSN = 0009-2614,
Unique-ID = ISI:A1987G806800006,
P. HOBZA and C. SANDORFY, "NONEMPIRICAL CALCULATIONS ON ALL THE 29 POSSIBLE DNA-BASE PAIRS," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 109, iss. 5, pp. 1302-1307, 1987.
[Bibtex]
@article ISI:A1987G225600003,
Author = HOBZA, P and SANDORFY, C,
Title = NONEMPIRICAL CALCULATIONS ON ALL THE 29 POSSIBLE DNA-BASE PAIRS,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 1987,
Volume = 109,
Number = 5,
Pages = 1302-1307,
Month = MAR 4,
DOI = 10.1021/ja00239a003,
ISSN = 0002-7863,
Unique-ID = ISI:A1987G225600003,
1986
[Bibtex]
@article ISI:A1986E256200008,
Author = SCHLEYER, PV and SAWARYN, A and REED, AE and HOBZA, P,
Title = THE REMARKABLE STRUCTURE OF LITHIUM CYANIDE ISOCYANIDE,
Journal = JOURNAL OF COMPUTATIONAL CHEMISTRY,
Year = 1986,
Volume = 7,
Number = 5,
Pages = 666-672,
Month = OCT,
ISSN = 0192-8651,
Unique-ID = ISI:A1986E256200008,
SCF AND MP2 LEVELS," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 31, iss. 3-4, pp. 377-385, 1986.
[Bibtex]
@article ISI:A1986D391900013,
Author = HOBZA, P and SCHNEIDER, B and CARSKY, P and ZAHRADNIK, R,
Title = THE SUPERPOSITION ERROR PROBLEM - THE (HF)2 AND (H2O)2 COMPLEXES AT THE
SCF AND MP2 LEVELS,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1986,
Volume = 31,
Number = 3-4,
Pages = 377-385,
Month = JUL,
ISSN = 0166-1280,
Unique-ID = ISI:A1986D391900013,
(HCN)2, (CH2O)2 AND (C2H4)2," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 31, iss. 3-4, pp. 387-399, 1986.
[Bibtex]
@article ISI:A1986D391900014,
Author = HOBZA, P and MEHLHORN, A and CARSKY, P and ZAHRADNIK, R,
Title = STACKING INTERACTIONS - ABINITIO SCF AND MP2 STUDY ON (H2O)2, (H2S)2,
(HCN)2, (CH2O)2 AND (C2H4)2,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1986,
Volume = 31,
Number = 3-4,
Pages = 387-399,
Month = JUL,
ISSN = 0166-1280,
Unique-ID = ISI:A1986D391900014,
R. ZAHRADNIK and P. HOBZA, "WEAK INTERMOLECULAR INTERACTIONS - STATICS AND DYNAMICS," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 29, iss. 4, pp. 663-676, 1986.
[Bibtex]
@article ISI:A1986A691100008,
Author = ZAHRADNIK, R and HOBZA, P,
Title = WEAK INTERMOLECULAR INTERACTIONS - STATICS AND DYNAMICS,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1986,
Volume = 29,
Number = 4,
Pages = 663-676,
Month = APR,
DOI = 10.1002/qua.560290409,
ISSN = 0020-7608,
Unique-ID = ISI:A1986A691100008,
1985
R. ZAHRADNIK, B. SCHNEIDER, P. HOBZA, Z. HAVLAS, and H. HUBER, "DISCRIMINATIVE INTERACTIONS BETWEEN CHIRAL MOLECULES - INTERNAL
DISCRIMINATION IN 1,2-DIFLUOROHYDRAZINE," CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE, vol. 63, iss. 7, pp. 1639-1641, 1985.
[Bibtex]
@article ISI:A1985ANW9500047,
Author = ZAHRADNIK, R and SCHNEIDER, B and HOBZA, P and HAVLAS, Z and HUBER, H,
Title = DISCRIMINATIVE INTERACTIONS BETWEEN CHIRAL MOLECULES - INTERNAL
DISCRIMINATION IN 1,2-DIFLUOROHYDRAZINE,
Journal = CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE,
Year = 1985,
Volume = 63,
Number = 7,
Pages = 1639-1641,
DOI = 10.1139/v85-275,
ISSN = 0008-4042,
Unique-ID = ISI:A1985ANW9500047,
NA+, MG-2+, CA2+ AND NH4+ CATIONS," JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, vol. 2, iss. 6, pp. 1245-1254, 1985.
[Bibtex]
@article ISI:A1985AMK5300014,
Author = HOBZA, P and SANDORFY, C,
Title = PERTURBATION OF HYDROGEN-BONDS IN THE ADENINE ... THYMINE BASE PAIR BY
NA+, MG-2+, CA2+ AND NH4+ CATIONS,
Journal = JOURNAL OF BIOMOLECULAR STRUCTURE \& DYNAMICS,
Year = 1985,
Volume = 2,
Number = 6,
Pages = 1245-1254,
ISSN = 0739-1102,
Unique-ID = ISI:A1985AMK5300014,
1984
M. SZCZESNIAK, P. HOBZA, Z. LATAJKA, H. RATAJCZAK, and K. SKOWRONEK, "THE METHYLATION EFFECT IN AMINE=HF HYDROGEN-BONDED SYSTEMS - QUANTUM
CHEMICAL AND STATISTICAL THERMODYNAMIC STUDY," JOURNAL OF PHYSICAL CHEMISTRY, vol. 88, iss. 24, pp. 5923-5927, 1984.
[Bibtex]
@article ISI:A1984TU20800035,
Author = SZCZESNIAK, MM and HOBZA, P and LATAJKA, Z and RATAJCZAK, H and
SKOWRONEK, K,
Title = THE METHYLATION EFFECT IN AMINE=HF HYDROGEN-BONDED SYSTEMS - QUANTUM
CHEMICAL AND STATISTICAL THERMODYNAMIC STUDY,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1984,
Volume = 88,
Number = 24,
Pages = 5923-5927,
DOI = 10.1021/j150668a035,
ISSN = 0022-3654,
Unique-ID = ISI:A1984TU20800035,
P. HOBZA and J. SAUER, "MINIMAL BASIS SET MINI-1 POWERFUL TOOL FOR CALCULATING OF
MOLECULAR-INTERACTIONS .1. NEUTRAL COMPLEXES," THEORETICA CHIMICA ACTA, vol. 65, iss. 4, pp. 279-290, 1984.
[Bibtex]
@article ISI:A1984TD88200007,
Author = HOBZA, P and SAUER, J,
Title = MINIMAL BASIS SET MINI-1 POWERFUL TOOL FOR CALCULATING OF
MOLECULAR-INTERACTIONS .1. NEUTRAL COMPLEXES,
Journal = THEORETICA CHIMICA ACTA,
Year = 1984,
Volume = 65,
Number = 4,
Pages = 279-290,
DOI = 10.1007/BF00548253,
ISSN = 0040-5744,
Unique-ID = ISI:A1984TD88200007,
J. SAUER and P. HOBZA, "THE MINIMAL BASIS SET MINI-1 POWERFUL TOOL FOR CALCULATING
INTERMOLECULAR INTERACTIONS .2. IONIC COMPLEXES," THEORETICA CHIMICA ACTA, vol. 65, iss. 4, pp. 291-302, 1984.
[Bibtex]
@article ISI:A1984TD88200008,
Author = SAUER, J and HOBZA, P,
Title = THE MINIMAL BASIS SET MINI-1 POWERFUL TOOL FOR CALCULATING
INTERMOLECULAR INTERACTIONS .2. IONIC COMPLEXES,
Journal = THEORETICA CHIMICA ACTA,
Year = 1984,
Volume = 65,
Number = 4,
Pages = 291-302,
DOI = 10.1007/BF00548254,
ISSN = 0040-5744,
Unique-ID = ISI:A1984TD88200008,
P. HOBZA and C. SANDORFY, "QUANTUM CHEMICAL AND STATISTICAL THERMODYNAMIC INVESTIGATIONS OF
ANESTHETIC ACTIVITY .3. THE INTERACTION BETWEEN CH4, CH3CL, CH2CL2,
CHCL3, CCL4, AND AN O-H...O HYDROGEN-BOND," CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE, vol. 62, iss. 3, pp. 606-609, 1984.
[Bibtex]
@article ISI:A1984SG38500033,
Author = HOBZA, P and SANDORFY, C,
Title = QUANTUM CHEMICAL AND STATISTICAL THERMODYNAMIC INVESTIGATIONS OF
ANESTHETIC ACTIVITY .3. THE INTERACTION BETWEEN CH4, CH3CL, CH2CL2,
CHCL3, CCL4, AND AN O-H...O HYDROGEN-BOND,
Journal = CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE,
Year = 1984,
Volume = 62,
Number = 3,
Pages = 606-609,
DOI = 10.1139/v84-102,
ISSN = 0008-4042,
Unique-ID = ISI:A1984SG38500033,
DEUTERATED CHLOROFORM," BRITISH JOURNAL OF ANAESTHESIA, vol. 56, iss. 12, pp. 1447-1448, 1984.
[Bibtex]
@article ISI:A1984TZ61200021,
Author = HOBZA, P and MERCIER, P and SANDORFY, C,
Title = HYDROGEN-BONDING IN MECHANISMS OF ANESTHESIA TESTED WITH CHLOROFORM AND
DEUTERATED CHLOROFORM,
Journal = BRITISH JOURNAL OF ANAESTHESIA,
Year = 1984,
Volume = 56,
Number = 12,
Pages = 1447-1448,
ISSN = 0007-0912,
Unique-ID = ISI:A1984TZ61200021,
P. HOBZA, R. ZAHRADNIK, and J. LADIK, "ORIGIN OF HIGH-EFFICIENCY AND SPECIFICITY OF BIOCHEMICAL REACTIONS," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 26, iss. 5, pp. 857-872, 1984.
[Bibtex]
@article ISI:A1984TR74400022,
Author = HOBZA, P and ZAHRADNIK, R and LADIK, J,
Title = ORIGIN OF HIGH-EFFICIENCY AND SPECIFICITY OF BIOCHEMICAL REACTIONS,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1984,
Volume = 26,
Number = 5,
Pages = 857-872,
DOI = 10.1002/qua.560260523,
ISSN = 0020-7608,
Unique-ID = ISI:A1984TR74400022,
P. HOBZA and C. SANDORFY, "A QUANTUM CHEMICAL STUDY OF THE EFFECT OF NA+ ON THE HYDROGEN-BONDS IN
THE ADENINE-THYMINE BASE-PAIR," BIOPHYSICAL CHEMISTRY, vol. 19, iss. 3, pp. 201-209, 1984.
[Bibtex]
@article ISI:A1984ST83300002,
Author = HOBZA, P and SANDORFY, C,
Title = A QUANTUM CHEMICAL STUDY OF THE EFFECT OF NA+ ON THE HYDROGEN-BONDS IN
THE ADENINE-THYMINE BASE-PAIR,
Journal = BIOPHYSICAL CHEMISTRY,
Year = 1984,
Volume = 19,
Number = 3,
Pages = 201-209,
DOI = 10.1016/0301-4622(84)87002-7,
ISSN = 0301-4622,
Unique-ID = ISI:A1984ST83300002,
HYDROGEN-BONDS," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 16, iss. FEB, pp. 251-256, 1984.
[Bibtex]
@article ISI:A1984SE09900032,
Author = SANDORFY, C and BUCHET, R and HOBZA, P and RUELLE, P,
Title = THEORETICAL AND EXPERIMENTAL STUDIES OF BIOLOGICALLY IMPORTANT
HYDROGEN-BONDS,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1984,
Volume = 16,
Number = FEB,
Pages = 251-256,
ISSN = 0166-1280,
Unique-ID = ISI:A1984SE09900032,
P. HOBZA and P. SCHLEYER, "ON THE NATURE OF LIH2," CHEMICAL PHYSICS LETTERS, vol. 105, iss. 6, pp. 630-634, 1984.
[Bibtex]
@article ISI:A1984SN70700013,
Author = HOBZA, P and SCHLEYER, PV,
Title = ON THE NATURE OF LIH2,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1984,
Volume = 105,
Number = 6,
Pages = 630-634,
DOI = 10.1016/0009-2614(84)85671-7,
ISSN = 0009-2614,
Unique-ID = ISI:A1984SN70700013,
1983
M. SZCZESNIAK and P. HOBZA, "SEARCH FOR A SIMPLIFIED PROCEDURE FOR THE EVALUATION OF THE GIBBS
FREE-ENERGY OF HYDROGEN-BOND FORMATION," JOURNAL OF PHYSICAL CHEMISTRY, vol. 87, iss. 14, pp. 2608-2614, 1983.
[Bibtex]
@article ISI:A1983QZ08100028,
Author = SZCZESNIAK, MM and HOBZA, P,
Title = SEARCH FOR A SIMPLIFIED PROCEDURE FOR THE EVALUATION OF THE GIBBS
FREE-ENERGY OF HYDROGEN-BOND FORMATION,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1983,
Volume = 87,
Number = 14,
Pages = 2608-2614,
DOI = 10.1021/j100237a028,
ISSN = 0022-3654,
Unique-ID = ISI:A1983QZ08100028,
P. HOBZA and C. SANDORFY, "PERTURBATION OF HYDROGEN-BONDS IN THE ADENINE.THYMINE BASE PAIR BY NA+ -
A QUANTUM CHEMICAL STUDY," PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF
AMERICA-BIOLOGICAL SCIENCES, vol. 80, iss. 10, pp. 2859-2860, 1983.
[Bibtex]
@article ISI:A1983QR49600011,
Author = HOBZA, P and SANDORFY, C,
Title = PERTURBATION OF HYDROGEN-BONDS IN THE ADENINE.THYMINE BASE PAIR BY NA+ -
A QUANTUM CHEMICAL STUDY,
Journal = PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF
AMERICA-BIOLOGICAL SCIENCES,
Year = 1983,
Volume = 80,
Number = 10,
Pages = 2859-2860,
DOI = 10.1073/pnas.80.10.2859,
ISSN = 0027-8424,
Unique-ID = ISI:A1983QR49600011,
P. HOBZA and R. ZAHRADNIK, "VANDERWAALS MOLECULES - QUANTUM-CHEMISTRY, PHYSICAL-PROPERTIES, AND
REACTIVITY," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 23, iss. 1, pp. 325-338, 1983.
[Bibtex]
@article ISI:A1983PW98400025,
Author = HOBZA, P and ZAHRADNIK, R,
Title = VANDERWAALS MOLECULES - QUANTUM-CHEMISTRY, PHYSICAL-PROPERTIES, AND
REACTIVITY,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1983,
Volume = 23,
Number = 1,
Pages = 325-338,
DOI = 10.1002/qua.560230128,
ISSN = 0020-7608,
Unique-ID = ISI:A1983PW98400025,
[Bibtex]
@article ISI:A1983RA85800021,
Author = HUBER, H and HOBZA, P and ZAHRADNIK, R,
Title = ON THE APPLICABILITY OF THE FOGO PROCEDURE TO VANDERWAALS MOLECULES,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1983,
Volume = 12,
Number = AUG,
Pages = 245-257,
ISSN = 0166-1280,
Unique-ID = ISI:A1983RA85800021,
P. HOBZA, H. HOFMANN, and R. ZAHRADNIK, "INFLUENCE OF LOCAL ELECTRIC-FIELDS ON THE PROPERTIES AND REACTIVITY OF
HYDROGEN-BONDS - COMPLEXES BETWEEN (HF)2 AND (HCL)2 AND M LI+, NA+,
MG-2+," JOURNAL OF PHYSICAL CHEMISTRY, vol. 87, iss. 4, pp. 573-578, 1983.
[Bibtex]
@article ISI:A1983QC24700012,
Author = HOBZA, P and HOFMANN, HJ and ZAHRADNIK, R,
Title = INFLUENCE OF LOCAL ELECTRIC-FIELDS ON THE PROPERTIES AND REACTIVITY OF
HYDROGEN-BONDS - COMPLEXES BETWEEN (HF)2 AND (HCL)2 AND M LI+, NA+,
MG-2+,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1983,
Volume = 87,
Number = 4,
Pages = 573-578,
DOI = 10.1021/j100227a012,
ISSN = 0022-3654,
Unique-ID = ISI:A1983QC24700012,
1982
P. HOBZA, F. MULDER, and C. SANDORFY, "QUANTUM CHEMICAL AND STATISTICAL THERMODYNAMIC INVESTIGATIONS OF
ANESTHETIC ACTIVITY .2. THE INTERACTION BETWEEN CHLOROFORM, FLUOROFORM,
AND A N-H=O=C HYDROGEN-BOND," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 104, iss. 4, pp. 925-928, 1982.
[Bibtex]
@article ISI:A1982NC95400001,
Author = HOBZA, P and MULDER, F and SANDORFY, C,
Title = QUANTUM CHEMICAL AND STATISTICAL THERMODYNAMIC INVESTIGATIONS OF
ANESTHETIC ACTIVITY .2. THE INTERACTION BETWEEN CHLOROFORM, FLUOROFORM,
AND A N-H=O=C HYDROGEN-BOND,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 1982,
Volume = 104,
Number = 4,
Pages = 925-928,
DOI = 10.1021/ja00368a001,
ISSN = 0002-7863,
Unique-ID = ISI:A1982NC95400001,
[Bibtex]
@article ISI:A1982NG28300010,
Author = ZAHRADNIK, R and HOBZA, P and SAUER, J,
Title = SELECTED TOPICS IN BIOLOGICAL CATALYSIS,
Journal = CHEMICKE LISTY,
Year = 1982,
Volume = 76,
Number = 3,
Pages = 312-329,
ISSN = 0009-2770,
Unique-ID = ISI:A1982NG28300010,
BIOLOGICALLY IMPORTANT SYSTEMS," CHEMICKE LISTY, vol. 76, iss. 7, pp. 673-694, 1982.
[Bibtex]
@article ISI:A1982NY54000001,
Author = HOBZA, P and ZAHRADNIK, R,
Title = CALCULATION OF WEAK INTERMOLECULAR VANDERWAALS INTERACTIONS IN
BIOLOGICALLY IMPORTANT SYSTEMS,
Journal = CHEMICKE LISTY,
Year = 1982,
Volume = 76,
Number = 7,
Pages = 673-694,
ISSN = 0009-2770,
Unique-ID = ISI:A1982NY54000001,
1981
P. HOBZA, J. SAUER, C. MORGENEYER, J. HURYCH, and R. ZAHRADNIK, "BONDING ABILITY OF SURFACE SITES ON SILICA AND THEIR EFFECT ON
HYDROGEN-BONDS - A QUANTUM-CHEMICAL AND STATISTICAL THERMODYNAMIC
TREATMENT," JOURNAL OF PHYSICAL CHEMISTRY, vol. 85, iss. 26, pp. 4061-4067, 1981.
[Bibtex]
@article ISI:A1981MV53700022,
Author = HOBZA, P and SAUER, J and MORGENEYER, C and HURYCH, J and ZAHRADNIK, R,
Title = BONDING ABILITY OF SURFACE SITES ON SILICA AND THEIR EFFECT ON
HYDROGEN-BONDS - A QUANTUM-CHEMICAL AND STATISTICAL THERMODYNAMIC
TREATMENT,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1981,
Volume = 85,
Number = 26,
Pages = 4061-4067,
DOI = 10.1021/j150626a022,
ISSN = 0022-3654,
Unique-ID = ISI:A1981MV53700022,
P. HOBZA, M. SZCZESNIAK, and Z. LATAJKA, "HF-C1F - MINIMA ON THE 4-31G AND 4-31GSTAR ENERGY HYPERSURFACES AND
THERMODYNAMICS OF FORMATION," CHEMICAL PHYSICS LETTERS, vol. 82, iss. 3, pp. 469-472, 1981.
[Bibtex]
@article ISI:A1981MH69900021,
Author = HOBZA, P and SZCZESNIAK, MM and LATAJKA, Z,
Title = HF-C1F - MINIMA ON THE 4-31G AND 4-31GSTAR ENERGY HYPERSURFACES AND
THERMODYNAMICS OF FORMATION,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1981,
Volume = 82,
Number = 3,
Pages = 469-472,
DOI = 10.1016/0009-2614(81)85422-X,
ISSN = 0009-2614,
Unique-ID = ISI:A1981MH69900021,
P. HOBZA and R. ZAHRADNIK, "FORMATION OF HYDROGEN-BONDED VANDERWAALS MOLECULES - APPLICABILITY OF
3-21G INTERMOLECULAR INTERACTION ENERGIES," CHEMICAL PHYSICS LETTERS, vol. 82, iss. 3, pp. 473-477, 1981.
[Bibtex]
@article ISI:A1981MH69900022,
Author = HOBZA, P and ZAHRADNIK, R,
Title = FORMATION OF HYDROGEN-BONDED VANDERWAALS MOLECULES - APPLICABILITY OF
3-21G INTERMOLECULAR INTERACTION ENERGIES,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1981,
Volume = 82,
Number = 3,
Pages = 473-477,
DOI = 10.1016/0009-2614(81)85423-1,
ISSN = 0009-2614,
Unique-ID = ISI:A1981MH69900022,
DISPERSION ENERGY) OF THE STATIONARY-POINTS AND THERMODYNAMICS OF
FORMATION," THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE, vol. 2, iss. 3-4, pp. 241-247, 1981.
[Bibtex]
@article ISI:A1981MR92800003,
Author = HOBZA, P and HOFMANN, HJ and ZAHRADNIK, R,
Title = THE CO2 ... HF COMPLEX - A THEORETICAL-STUDY (4-31G,6-31G-STAR +
DISPERSION ENERGY) OF THE STATIONARY-POINTS AND THERMODYNAMICS OF
FORMATION,
Journal = THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE,
Year = 1981,
Volume = 2,
Number = 3-4,
Pages = 241-247,
ISSN = 0166-1280,
Unique-ID = ISI:A1981MR92800003,
P. HOBZA, F. MULDER, and C. SANDORFY, "QUANTUM CHEMICAL AND STATISTICAL THERMODYNAMIC INVESTIGATIONS OF
ANESTHETIC ACTIVITY .1. THE INTERACTION BETWEEN CHLOROFORM, FLUOROFORM,
CYCLOPROPANE, AND AN O-H=O HYDROGEN-BOND," JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 103, iss. 6, pp. 1360-1366, 1981.
[Bibtex]
@article ISI:A1981LH28600011,
Author = HOBZA, P and MULDER, F and SANDORFY, C,
Title = QUANTUM CHEMICAL AND STATISTICAL THERMODYNAMIC INVESTIGATIONS OF
ANESTHETIC ACTIVITY .1. THE INTERACTION BETWEEN CHLOROFORM, FLUOROFORM,
CYCLOPROPANE, AND AN O-H=O HYDROGEN-BOND,
Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY,
Year = 1981,
Volume = 103,
Number = 6,
Pages = 1360-1366,
DOI = 10.1021/ja00396a011,
ISSN = 0002-7863,
Unique-ID = ISI:A1981LH28600011,
1980
THERMODYNAMICS OF FORMATION AND REACTIVITY," TOPICS IN CURRENT CHEMISTRY, vol. 93, pp. 53-90, 1980.
[Bibtex]
@article ISI:A1980LJ55100002,
Author = HOBZA, P and ZAHRADNIK, R,
Title = VANDERWAALS SYSTEMS - MOLECULAR-ORBITALS, PHYSICAL-PROPERTIES,
THERMODYNAMICS OF FORMATION AND REACTIVITY,
Journal = TOPICS IN CURRENT CHEMISTRY,
Year = 1980,
Volume = 93,
Pages = 53-90,
ISSN = 0342-6793,
Unique-ID = ISI:A1980LJ55100002,
J. SAUER, P. HOBZA, and R. ZAHRADNIK, "QUANTUM CHEMICAL INVESTIGATION OF INTERACTION SITES IN ZEOLITES AND
SILICA," JOURNAL OF PHYSICAL CHEMISTRY, vol. 84, iss. 24, pp. 3318-3326, 1980.
[Bibtex]
@article ISI:A1980KS40900036,
Author = SAUER, J and HOBZA, P and ZAHRADNIK, R,
Title = QUANTUM CHEMICAL INVESTIGATION OF INTERACTION SITES IN ZEOLITES AND
SILICA,
Journal = JOURNAL OF PHYSICAL CHEMISTRY,
Year = 1980,
Volume = 84,
Number = 24,
Pages = 3318-3326,
DOI = 10.1021/j100461a036,
ISSN = 0022-3654,
Unique-ID = ISI:A1980KS40900036,
P. HOBZA, M. SZCZESNIAK, and Z. LATAJKA, "HF-HCL - STATIONARY-POINTS ON THE SCF ENERGY HYPERSURFACE AND
THERMODYNAMICS OF FORMATION," CHEMICAL PHYSICS LETTERS, vol. 74, iss. 2, pp. 248-251, 1980.
[Bibtex]
@article ISI:A1980KH90200010,
Author = HOBZA, P and SZCZESNIAK, MM and LATAJKA, Z,
Title = HF-HCL - STATIONARY-POINTS ON THE SCF ENERGY HYPERSURFACE AND
THERMODYNAMICS OF FORMATION,
Journal = CHEMICAL PHYSICS LETTERS,
Year = 1980,
Volume = 74,
Number = 2,
Pages = 248-251,
DOI = 10.1016/0009-2614(80)85151-7,
ISSN = 0009-2614,
Unique-ID = ISI:A1980KH90200010,
VANDERWAALS MOLECULES FORMED BY POLAR-MOLECULES," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 45, iss. 5, pp. 1323-1330, 1980.
[Bibtex]
@article ISI:A1980JW46400002,
Author = HOBZA, P and PANCIR, J and ZAHRADNIK, R,
Title = NATURE OF STATIONARY-POINTS ON CNDO-2 ENERGY HYPERSURFACES OF
VANDERWAALS MOLECULES FORMED BY POLAR-MOLECULES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1980,
Volume = 45,
Number = 5,
Pages = 1323-1330,
ISSN = 0010-0765,
Unique-ID = ISI:A1980JW46400002,
[Bibtex]
@article ISI:A1980KZ39200007,
Author = URBAN, M and HRIVNAKOVA, S and HOBZA, P,
Title = ABINITIO STUDY OF THE (BH)2 DIMER,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1980,
Volume = 45,
Number = 12,
Pages = 3270-3282,
ISSN = 0010-0765,
Unique-ID = ISI:A1980KZ39200007,
1979
P. HOBZA, P. CARSKY, and R. ZAHRADNIK, "CLUSTERS OF HYDROGEN MOLECULES - ABINITIO SCF CALCULATIONS CORRECTED
SEMI-EMPIRICALLY FOR CORRELATION ENERGIES," THEORETICA CHIMICA ACTA, vol. 53, iss. 1, pp. 1-7, 1979.
[Bibtex]
@article ISI:A1979HS88200001,
Author = HOBZA, P and CARSKY, P and ZAHRADNIK, R,
Title = CLUSTERS OF HYDROGEN MOLECULES - ABINITIO SCF CALCULATIONS CORRECTED
SEMI-EMPIRICALLY FOR CORRELATION ENERGIES,
Journal = THEORETICA CHIMICA ACTA,
Year = 1979,
Volume = 53,
Number = 1,
Pages = 1-7,
DOI = 10.1007/BF00547603,
ISSN = 0040-5744,
Unique-ID = ISI:A1979HS88200001,
AND THE ROLE OF ENTROPY IN THE DIMER FORMATION," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 44, iss. 12, pp. 3458-3463, 1979.
[Bibtex]
@article ISI:A1979JB27600006,
Author = HOBZA, P and CARSKY, P and ZAHRADNIK, R,
Title = DIMER (HCI)2 - STATIONARY-POINTS ON THE SCF 4-31G ENERGY HYPERSURFACE
AND THE ROLE OF ENTROPY IN THE DIMER FORMATION,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1979,
Volume = 44,
Number = 12,
Pages = 3458-3463,
ISSN = 0010-0765,
Unique-ID = ISI:A1979JB27600006,
P. HOBZA, P. CARSKY, and R. ZAHRADNIK, "ROLE OF ENTROPY IN FORMATION OF VANDERWAALS COMPLEXES," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 16, iss. 2, pp. 257-260, 1979.
[Bibtex]
@article ISI:A1979HJ53300005,
Author = HOBZA, P and CARSKY, P and ZAHRADNIK, R,
Title = ROLE OF ENTROPY IN FORMATION OF VANDERWAALS COMPLEXES,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1979,
Volume = 16,
Number = 2,
Pages = 257-260,
DOI = 10.1002/qua.560160206,
ISSN = 0020-7608,
Unique-ID = ISI:A1979HJ53300005,
R. LOCHMANN and P. HOBZA, "PCILO CALCULATIONS ON TRUE VANDERWAALS COMPLEXES," INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, vol. 15, iss. 1, pp. 73-81, 1979.
[Bibtex]
@article ISI:A1979GF71800007,
Author = LOCHMANN, R and HOBZA, P,
Title = PCILO CALCULATIONS ON TRUE VANDERWAALS COMPLEXES,
Journal = INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY,
Year = 1979,
Volume = 15,
Number = 1,
Pages = 73-81,
DOI = 10.1002/qua.560150108,
ISSN = 0020-7608,
Unique-ID = ISI:A1979GF71800007,
1978
METHYL-DERIVATIVES THEREOF," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 43, iss. 5, pp. 1366-1374, 1978.
[Bibtex]
@article ISI:A1978FD12900020,
Author = THANG, ND and HOBZA, P and PANCIR, J and ZAHRADNIK, R,
Title = SEMI-EMPIRICAL ENERGY HYPERSURFACE OF FORMALDEHYDE-WATER COMPLEX AND
METHYL-DERIVATIVES THEREOF,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1978,
Volume = 43,
Number = 5,
Pages = 1366-1374,
ISSN = 0010-0765,
Unique-ID = ISI:A1978FD12900020,
STRUCTURES OF PROTONATED BENZENE," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 43, iss. 11, pp. 3020-3023, 1978.
[Bibtex]
@article ISI:A1978FY36800024,
Author = HEIDRICH, D and HOBZA, P and CARSKY, P and ZAHRADNIK, R,
Title = EFFECT OF CORRELATION ENERGY ON STABILITY OF CLASSICAL AND NON-CLASSICAL
STRUCTURES OF PROTONATED BENZENE,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1978,
Volume = 43,
Number = 11,
Pages = 3020-3023,
ISSN = 0010-0765,
Unique-ID = ISI:A1978FY36800024,
COMPLEXES AND ENERGIES OF REACTION," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 43, iss. 3, pp. 676-680, 1978.
[Bibtex]
@article ISI:A1978EU61600002,
Author = HOBZA, P and CARSKY, P and ZAHRADNIK, R,
Title = SEMI-EMPIRICAL EPCE-F2SIGMA CORRELATION ENERGIES FOR VANDERWAALS
COMPLEXES AND ENERGIES OF REACTION,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1978,
Volume = 43,
Number = 3,
Pages = 676-680,
ISSN = 0010-0765,
Unique-ID = ISI:A1978EU61600002,
P. HOBZA and J. HURYCH, "QUANTUM CHEMICAL STUDY OF PROPERTIES AND REACTIVITY OF QUARTZ DUST .1.
ELECTRONIC-STRUCTURE OF ALPHA-QUARTZ," ENVIRONMENTAL RESEARCH, vol. 15, iss. 3, pp. 432-442, 1978.
[Bibtex]
@article ISI:A1978FF43100011,
Author = HOBZA, P and HURYCH, J,
Title = QUANTUM CHEMICAL STUDY OF PROPERTIES AND REACTIVITY OF QUARTZ DUST .1.
ELECTRONIC-STRUCTURE OF ALPHA-QUARTZ,
Journal = ENVIRONMENTAL RESEARCH,
Year = 1978,
Volume = 15,
Number = 3,
Pages = 432-442,
DOI = 10.1016/0013-9351(78)90124-X,
ISSN = 0013-9351,
Unique-ID = ISI:A1978FF43100011,
INTER-MOLECULAR POTENTIAL," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 43, iss. 5, pp. 1356-1365, 1978.
[Bibtex]
@article ISI:A1978FD12900019,
Author = HAVLAS, Z and HOBZA, P and ZAHRADNIK, R,
Title = WEAK INTER-MOLECULAR INTERACTIONS .8. ATTEMPT TO CONSTRUCT A HYBRID
INTER-MOLECULAR POTENTIAL,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1978,
Volume = 43,
Number = 5,
Pages = 1356-1365,
ISSN = 0010-0765,
Unique-ID = ISI:A1978FD12900019,
CALCULATIONS," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 43, iss. 3, pp. 665-675, 1978.
[Bibtex]
@article ISI:A1978EU61600001,
Author = HOBZA, P and BOCEK, K and HOFMANN, HJ and SLANINA, Z and ZAHRADNIK, R,
Title = GAS-PHASE AND LIQUID-PHASE HYDRATION OF METHANOL - ENTHALPY AND ENTROPY
CALCULATIONS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1978,
Volume = 43,
Number = 3,
Pages = 665-675,
ISSN = 0010-0765,
Unique-ID = ISI:A1978EU61600001,
1977
P. HOBZA and R. ZAHRADNIK, "ELECTRONIC-STRUCTURE OF ESTABLISHED AND POTENTIAL OXIDIZING-AGENTS IN
BIOLOGICAL-SYSTEMS," JOURNAL OF THEORETICAL BIOLOGY, vol. 66, iss. 3, pp. 461-474, 1977.
[Bibtex]
@article ISI:A1977DM20700004,
Author = HOBZA, P and ZAHRADNIK, R,
Title = ELECTRONIC-STRUCTURE OF ESTABLISHED AND POTENTIAL OXIDIZING-AGENTS IN
BIOLOGICAL-SYSTEMS,
Journal = JOURNAL OF THEORETICAL BIOLOGY,
Year = 1977,
Volume = 66,
Number = 3,
Pages = 461-474,
DOI = 10.1016/0022-5193(77)90296-X,
ISSN = 0022-5193,
Unique-ID = ISI:A1977DM20700004,
EFFECTS ON PROPERTIES OF MOLECULES - SOLVATION ENERGY AND PHYSICAL
CHARACTERISTIC," CHEMICKE LISTY, vol. 71, iss. 8, pp. 807-821, 1977.
[Bibtex]
@article ISI:A1977DQ20800002,
Author = HOBZA, P and ZAHRADNIK, R,
Title = SELECTED CHAPTERS FROM APPLIED QUANTUM CHEMISTRY .27. ENVIRONMENTAL
EFFECTS ON PROPERTIES OF MOLECULES - SOLVATION ENERGY AND PHYSICAL
CHARACTERISTIC,
Journal = CHEMICKE LISTY,
Year = 1977,
Volume = 71,
Number = 8,
Pages = 807-821,
ISSN = 0009-2770,
Unique-ID = ISI:A1977DQ20800002,
1976
COMPLEXES BASED ON ANALYSIS OF INTERMOLECULAR FORCES," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 41, iss. 4, pp. 1111-1120, 1976.
[Bibtex]
@article ISI:A1976BQ08800019,
Author = HOBZA, P and ZAHRADNIK, R,
Title = WEAK INTERMOLECULAR INTERACTIONS .6. ESTIMATES OF GEOMETRY OF MOLECULAR
COMPLEXES BASED ON ANALYSIS OF INTERMOLECULAR FORCES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1976,
Volume = 41,
Number = 4,
Pages = 1111-1120,
ISSN = 0010-0765,
Unique-ID = ISI:A1976BQ08800019,
INTERACTION ENERGIES OF CLUSTERS OF MOLECULES - CORRELATION WITH HEATS
OF VAPORIZATION," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 41, iss. 6, pp. 1727-1739, 1976.
[Bibtex]
@article ISI:A1976BW48100014,
Author = HOBZA, P and STRUZINSKY, R and DUCTHANG, N and ZAHRADNIK, R,
Title = WEAK INTERMOLECULAR INTERACTIONS .7. EMPIRICAL CALCULATIONS ON
INTERACTION ENERGIES OF CLUSTERS OF MOLECULES - CORRELATION WITH HEATS
OF VAPORIZATION,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1976,
Volume = 41,
Number = 6,
Pages = 1727-1739,
ISSN = 0010-0765,
Unique-ID = ISI:A1976BW48100014,
1975
[Bibtex]
@article ISI:A1975W188700022,
Author = ZAHRADNIK, R and HOBZA, P and SLANINA, Z,
Title = CALCULATIONS OF HENRY CONSTANTS AND PARTITION-COEFFICIENTS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1975,
Volume = 40,
Number = 3,
Pages = 799-808,
ISSN = 0010-0765,
Unique-ID = ISI:A1975W188700022,
IDENTICAL NONPOLAR SYSTEMS," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 40, iss. 3, pp. 809-814, 1975.
[Bibtex]
@article ISI:A1975W188700023,
Author = HOBZA, P and ZAHRADNIK, R,
Title = SEMIEMPIRICAL VARIATION CALCULATIONS ON INTERACTION ENERGY OF 2
IDENTICAL NONPOLAR SYSTEMS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1975,
Volume = 40,
Number = 3,
Pages = 809-814,
ISSN = 0010-0765,
Unique-ID = ISI:A1975W188700023,
P. CARSKY, R. ZAHRADNIK, and P. HOBZA, "SEMIEMPIRICAL ESTIMATES OF CORRELATION ENERGY IN SMALL CLUSTERS OF
HYDROGEN-ATOMS," THEORETICA CHIMICA ACTA, vol. 40, iss. 4, pp. 287-295, 1975.
[Bibtex]
@article ISI:A1975BE62800003,
Author = CARSKY, P and ZAHRADNIK, R and HOBZA, P,
Title = SEMIEMPIRICAL ESTIMATES OF CORRELATION ENERGY IN SMALL CLUSTERS OF
HYDROGEN-ATOMS,
Journal = THEORETICA CHIMICA ACTA,
Year = 1975,
Volume = 40,
Number = 4,
Pages = 287-295,
DOI = 10.1007/BF00668334,
ISSN = 0040-5744,
Unique-ID = ISI:A1975BE62800003,
M. URBAN and P. HOBZA, "WEAK INTERMOLECULAR INTERACTION .3. AB-INITIO SCF CALCULATION OF
INTERACTION ENERGY AND ITS COMPONENTS NEAR VAN WAALS MINIMUM," THEORETICA CHIMICA ACTA, vol. 36, iss. 3, pp. 207-214, 1975.
[Bibtex]
@article ISI:A1975V434000005,
Author = URBAN, M and HOBZA, P,
Title = WEAK INTERMOLECULAR INTERACTION .3. AB-INITIO SCF CALCULATION OF
INTERACTION ENERGY AND ITS COMPONENTS NEAR VAN WAALS MINIMUM,
Journal = THEORETICA CHIMICA ACTA,
Year = 1975,
Volume = 36,
Number = 3,
Pages = 207-214,
DOI = 10.1007/BF00572560,
ISSN = 0040-5744,
Unique-ID = ISI:A1975V434000005,
M. URBAN and P. HOBZA, "WEAK INTERMOLECULAR INTERACTION .4. APPLICATION OF FUNCTION COUNTERPOISE
METHOD TO CALCULATION OF INTERACTION ENERGY AND ITS COMPONENTS," THEORETICA CHIMICA ACTA, vol. 36, iss. 3, pp. 215-220, 1975.
[Bibtex]
@article ISI:A1975V434000006,
Author = URBAN, M and HOBZA, P,
Title = WEAK INTERMOLECULAR INTERACTION .4. APPLICATION OF FUNCTION COUNTERPOISE
METHOD TO CALCULATION OF INTERACTION ENERGY AND ITS COMPONENTS,
Journal = THEORETICA CHIMICA ACTA,
Year = 1975,
Volume = 36,
Number = 3,
Pages = 215-220,
DOI = 10.1007/BF00572561,
ISSN = 0040-5744,
Unique-ID = ISI:A1975V434000006,
STUDIES," CHEMICKE LISTY, vol. 69, iss. 9, pp. 897-914, 1975.
[Bibtex]
@article ISI:A1975AS32600001,
Author = ZAHRADNIK, R and HOBZA, P and SLANINA, Z and CARSKY, P,
Title = HYDROGEN AND ITS AGGREGATES - REVIEW OF RESULTS OF QUANTUM CHEMICAL
STUDIES,
Journal = CHEMICKE LISTY,
Year = 1975,
Volume = 69,
Number = 9,
Pages = 897-914,
ISSN = 0009-2770,
Unique-ID = ISI:A1975AS32600001,
COLLISION COMPLEXES AND ITS SEMIEMPIRICAL CALCULATIONS," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 40, iss. 6, pp. 1801-1810, 1975.
[Bibtex]
@article ISI:A1975AH57300018,
Author = HORAK, M and HILGARD, S and HOBZA, P,
Title = STUDIES OF SOLUTE-SOLVENT INTERACTIONS .7. STABILIZATION ENERGY OF
COLLISION COMPLEXES AND ITS SEMIEMPIRICAL CALCULATIONS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1975,
Volume = 40,
Number = 6,
Pages = 1801-1810,
ISSN = 0010-0765,
Unique-ID = ISI:A1975AH57300018,
1974
INTERACTIONS BETWEEN NONPOLAR MOLECULE NONPOLAR MOLECULE AND POLAR
MOLECULE POLAR MOLECULE," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 39, iss. 10, pp. 2866-2876, 1974.
[Bibtex]
@article ISI:A1974U571700019,
Author = HOBZA, P and ZAHRADNI.R,
Title = WEAK INTERMOLECULAR INTERACTIONS .2. PERTURBATION TREATMENT OF
INTERACTIONS BETWEEN NONPOLAR MOLECULE NONPOLAR MOLECULE AND POLAR
MOLECULE POLAR MOLECULE,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1974,
Volume = 39,
Number = 10,
Pages = 2866-2876,
ISSN = 0010-0765,
Unique-ID = ISI:A1974U571700019,
IN CHEMISTRY," CHEMICKE LISTY, vol. 68, iss. 7, pp. 673-695, 1974.
[Bibtex]
@article ISI:A1974T704500001,
Author = HOBZA, P and ZAHRADNI.R,
Title = SELECTED CHAPTERS FROM APPLIED QUANTUM CHEMISTRY .10. WEAK INTERACTIONS
IN CHEMISTRY,
Journal = CHEMICKE LISTY,
Year = 1974,
Volume = 68,
Number = 7,
Pages = 673-695,
ISSN = 0009-2770,
Unique-ID = ISI:A1974T704500001,
DIMERIZATION OF HOMONUCLEAR BIATOMIC MOLECULES," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 39, iss. 1, pp. 228-235, 1974.
[Bibtex]
@article ISI:A1974R992200030,
Author = SLANINA, Z and HOBZA, P and ZAHRADNI.R,
Title = CALCULATION OF ABSOLUTE VALUES OF EQUILIBRIUM AND RATE CONSTANTS .2.
DIMERIZATION OF HOMONUCLEAR BIATOMIC MOLECULES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1974,
Volume = 39,
Number = 1,
Pages = 228-235,
ISSN = 0010-0765,
Unique-ID = ISI:A1974R992200030,
[Bibtex]
@article ISI:A1974U571700018,
Author = HOBZA, P and ZAHRADNI.R,
Title = WEAK INTERMOLECULAR INTERACTIONS - INTRODUCTORY-REMARKS AND METHODS USED,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1974,
Volume = 39,
Number = 10,
Pages = 2857-2865,
ISSN = 0010-0765,
Unique-ID = ISI:A1974U571700018,
1973
P. HOBZA, J. HURYCH, and ZAHRADNI.R, "QUANTUM CHEMICAL STUDY OF MECHANISM OF COLLAGEN PROLINE HYDROXYLATION," BIOCHIMICA ET BIOPHYSICA ACTA, vol. 304, iss. 2, pp. 466-472, 1973.
[Bibtex]
@article ISI:A1973P638100028,
Author = HOBZA, P and HURYCH, J and ZAHRADNI.R,
Title = QUANTUM CHEMICAL STUDY OF MECHANISM OF COLLAGEN PROLINE HYDROXYLATION,
Journal = BIOCHIMICA ET BIOPHYSICA ACTA,
Year = 1973,
Volume = 304,
Number = 2,
Pages = 466-472,
DOI = 10.1016/0304-4165(73)90266-3,
ISSN = 0006-3002,
Unique-ID = ISI:A1973P638100028,
SEMIEMPIRICAL OPEN-SHELL PPP-LIKE CALCULATIONS," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 38, iss. 5, pp. 1459-1462, 1973.
[Bibtex]
@article ISI:A1973P774400025,
Author = NYKL, I and FOJTIK, A and HOBZA, P and CARSKY, P and ZAHRADNI.R and
SHIDA, T,
Title = ELECTRONIC-SPECTRA OF AZULENE MONONEGATIVE AND MONOPOSITIVE IONS AND
SEMIEMPIRICAL OPEN-SHELL PPP-LIKE CALCULATIONS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1973,
Volume = 38,
Number = 5,
Pages = 1459-1462,
ISSN = 0010-0765,
Unique-ID = ISI:A1973P774400025,
PENTALENO[6,6A,1,2-DEF]HEPTALENE AND 2-PHENYLCYCLOPENT[CD]AZULENE
AND SEMIEMPIRICAL OPEN-SHELL PPP-LIKE CALCULATIONS," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 38, iss. 5, pp. 1463-1465, 1973.
[Bibtex]
@article ISI:A1973P774400026,
Author = NYKL, I and REJHOLEC, V and HOBZA, P and CARSKY, P and ZAHRADNI.R and
HAFNER, K,
Title = CONJUGATED RADICALS .17. ELECTRONIC-SPECTRA OF RADICAL IONS DERIVED FROM
PENTALENO[6,6A,1,2-DEF]HEPTALENE AND 2-PHENYLCYCLOPENT[CD]AZULENE
AND SEMIEMPIRICAL OPEN-SHELL PPP-LIKE CALCULATIONS,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1973,
Volume = 38,
Number = 5,
Pages = 1463-1465,
ISSN = 0010-0765,
Unique-ID = ISI:A1973P774400026,
REMARK ON APPLICABILITY OF LCI-CNDO METHOD TO QUINONES AND SEMIQUINONES," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 38, iss. 3, pp. 641-644, 1973.
[Bibtex]
@article ISI:A1973P256200003,
Author = HOBZA, P and CARSKY, P and ZAHRADNI.R,
Title = CONJUGATED RADICALS .16. ELECTRONIC-SPECTRA OF ORTHO-SEMIQUINONES AND A
REMARK ON APPLICABILITY OF LCI-CNDO METHOD TO QUINONES AND SEMIQUINONES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1973,
Volume = 38,
Number = 3,
Pages = 641-644,
ISSN = 0010-0765,
Unique-ID = ISI:A1973P256200003,
ELECTRONIC-SPECTRA," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 38, iss. 4, pp. 994-997, 1973.
[Bibtex]
@article ISI:A1973P508900006,
Author = HOBZA, P and NYKL, I and UHLIR, K,
Title = ELECTROCHEMICAL EQUIPMENT FOR GENERATION OF RADICALS AND RECORDING
ELECTRONIC-SPECTRA,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1973,
Volume = 38,
Number = 4,
Pages = 994-997,
ISSN = 0010-0765,
Unique-ID = ISI:A1973P508900006,
1972
CALCULATIONS ON RADICAL ANIONS OF ACENAPHTHYLENE, FLUORANTHENE AND
ACEHEPTYLENE," COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS, vol. 37, iss. 6, pp. 1983-&, 1972.
[Bibtex]
@article ISI:A1972M880700028,
Author = ZAHRADNI.R and CARSKY, P and REJHOLEC, V and HAFNER, K and HOBZA, P,
Title = CONJUGATED RADICALS .14. ELECTRONIC-SPECTRA AND SEMIEMPIRICAL
CALCULATIONS ON RADICAL ANIONS OF ACENAPHTHYLENE, FLUORANTHENE AND
ACEHEPTYLENE,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1972,
Volume = 37,
Number = 6,
Pages = 1983-\&,
ISSN = 0010-0765,
Unique-ID = ISI:A1972M880700028,
1971
ZAHRADNI.R, P. HOBZA, and J. HURYCH, "MOLECULAR-ORBITAL STUDY OF HYDROXYLATION OF COLLAGENOUS PROLINE AND
LYSINE," BIOCHIMICA ET BIOPHYSICA ACTA, vol. 251, iss. 3, pp. 314-&, 1971.
[Bibtex]
@article ISI:A1971L287700004,
Author = ZAHRADNI.R and HOBZA, P and HURYCH, J,
Title = MOLECULAR-ORBITAL STUDY OF HYDROXYLATION OF COLLAGENOUS PROLINE AND
LYSINE,
Journal = BIOCHIMICA ET BIOPHYSICA ACTA,
Year = 1971,
Volume = 251,
Number = 3,
Pages = 314-\&,
DOI = 10.1016/0005-2795(71)90117-6,
ISSN = 0006-3002,
Unique-ID = ISI:A1971L287700004,
[Bibtex]
@article ISI:A1971J210800021,
Author = CARSKY, P and HOBZA, P and ZAHRADNI.R,
Title = CONJUGATED RADICALS .11. PARA SEMIQUINONES,
Journal = COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS,
Year = 1971,
Volume = 36,
Number = 3,
Pages = 1291-\&,
ISSN = 0010-0765,
Unique-ID = ISI:A1971J210800021,