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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of structural chemistry 30 (1989), S. 605-612 
    ISSN: 1573-8779
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions By finding a F-structure corresponding to a certain instantaneous configuration (I-structure), it becomes possible to examine pairs of molecules and determine which of them form hydrogen bonds, even in the case of pairs of molecules for which it would otherwise be difficult to say whether or not they participate in hydrogen bonding. In the F-structure obtained for water, less than 10% of the hydroxyl groups do not participate in hydrogen bonds, and three-quarters of the molecules are tetrahedrally coordinated. The hydrogen bond criterion based on binding F-structures (i. e., on a search for the closest local mininum in the potential energy) that is used in modeling by the Monte Carlo method can be likened in some degree to a previously proposed dynamic criterion applied in molecular-dynamic modeling [26]. Both criteria take into account not only the instantaneous state, but also the “fate” of a particular pair at the closest moment of time (molecular dynamics) or after a lowering of the temperature (Monte Carlo). Of course, in order to reveal the fundamental relationships in liquid structure, it is necessary to obtain a representative set of F-structures [30], which requires major expenditures of machine time.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 35 (1989), S. 91-102 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational properties of some nucleotide sequences result in their ability to bind specifically some ligands or tobe recognized by specific proteins. In order to investigate the dependence of conformational behavior of the DNA duplex on nucleotide sequence, we analyzed the interaction energy of nucleic acid bases as a function of conformational parameters and base sequence. Extended regions of minimum energy values were found for different sequences. Although these regions (valleys) largely overlap, each one shows specificity for a particular sequence. This suggests that a specific pathway of changes in conformational parameters exists for each sequence. the changes may be accompanied by considerable shifts (2-3 Å) of the atom positions and an only slight variation (1-2 kcal/mol) of energy. Even small shifts in other directions can cause a drastic energy increase. For some nucleotide sequences, the energetically preferable conformations are the B-like ones (e.g., ApA, TpA), whereas for others the A-like ones are preferable (e.g., GpG, ApT). IN general, Pyr-Pur sequences have a tendency to a larger τ and smaller H and D than Pur-Pyr sequences. A large body of experimental data on nucleic acid structure in fibers and in solutions can be explained by results obtained.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 42 (1992), S. 1499-1514 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results of the Monte Carlo Metropolis simulation of water structure and of the hydration of nucleic acid fragments, complementary base pairs and mispairs, base pair stacks, and duplex fragments have been summarized. Systematic investigations suggest some general conclusions: (1) the hydration shell structure of the major and minor grooves of the duplex depends significantly on DNA conformation (or stack configuration) and nucleotide sequence, while global hydration characteristics (average energy, the number of water-water and water-base H-bonds) are only slightly dependent on these factors, (2) hydration economy takes place in the B-A transition due to an increase of the number of water molecules forming hydrogen bonds with two or more atoms of bases (water bridging), and (3) the hydration of the duplex could contribute to nucleic acid functioning via water-bridged mispair formation and stabilization of specific conformations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-9171
    Keywords: hydration ; computer simulation ; Monte Carlo ; potential functions ; intermolecular interactions ; nucleic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Three systems of potential functions (PF) which are used in simulations of hydration of bioorganic molecules have been compared: Poltev and Malenkov (PM), Weiner and Kollman (WK) (used in the widespread AMBER program), and OPLS (optimized potentials for liquid simulations) of Jorgensen (J). The values of interaction energies of individual water molecules with single molecules of nucleic bases calculatedvia PM potentials are in somewhat better accord with mass spectrometric data than those calculatedvia WK PF. OPLS give much smaller energy values for all compounds considered; therefore they were not used in further computations. Monte Carlo simulation of hydration of 9-methyladenine, 1-methyluracil, and 1-methylthymine in systems with 300 water molecules and periodic boundary conditions have been performed. Simulations with PM potentials give better agreement with the experimental data on hydration energies than those with WK PF that allows to prefer PM PF for simulation of hydration of nucleic acids.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydration shell of several conformations of the polynucleotides poly(dA) · poly(dT), poly (dA) · poly (dU), and poly (dA-dl) · poly (dT-dC) has been simulated using the Monte Carlo method (Metropolis sampling). Calculations have shown that the structure of the hydration shell of the minor groove greatly depends on its width. In conformations with a narrowed minor groove, the first layer of the hydration shell of this groove has only one molecule per nucleotide pair that forms H bonds with purine N3 of one pair and pyrimidine O2 of the next pair. The second layer of the hydration shell of such conformations contains molecules that form H bonds between two adjacent molecules of the first layer. The probability of formation of hydration spine is about 20% while the bridges of the first layer are formed with a probability of about 70%.In the first layer of the minor groove of the B-DNA conformation with wide minor groove there are approximately two water molecules per base pair that form H bonds with purine N3 or pyrimidine O2 and with the sugar ring oxygen of the adjacent nucleotide. The probability of simultaneous H bonding of a water molecule with N3 (or O2) and O of sugar ring is about 30%.The results of simulation suggest that hydration spine proposed for the narrowed minor groove of oligonucleotide crystals [H. R. Drew, and R. E. Dickerson (1981) Journal of Molecular Biology, Vol. 151, pp. 535-556] can be formed in fibers of poly (dA) · poly (dT), poly (dA) · poly (dU), and poly (dA-dl) · poly (dT-dC) as well as in DNA fragments of these sequences in solution. The role of the hydration shell of the minor groove of DNA double helix in stabilization of certain B-family conformations is discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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