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V I Poltev

Publications and source records attributed to V I Poltev.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

[Molecular mechanisms of 2-aminopurine and 2,6-diaminopurine induced mutations].

Molecular mechanisms of base pair substitutions induced by 2-aminopurine and 2,6-diaminopurine have been proposed by calculations of nonbonded interaction energy of this substances with nucleic acid bases. The calculation results suppose that the main pathways of the transitions are wobble pair formations of these analogues with cytosine. The possibility of the transversions as a result of incorporation of 2-aminopurine and 2,6-diaminopurine in DNA have been considered. The influence of nucleotide sequences and enzymes of nucleic acid synthesis on induced mutation frequencies have been discussed.

2-Aminopurine↗
PubMedDate not supplied

[Contribution of individual structural components to stabilization of the secondary structure of double-helical polynucleotides].

Contributions of individual structural components of the double-helical polynucleotide to the stabilization of its secondary structure have been studied. The energy of intramolecular interactions was calculated by the method of atom-atom potentials. Sections of the energy function were constructed according to the parameters determining mutual location of base pairs with the optimal conformation of ribose-phosphate backbone in the points close to A- and B-forms of DNA. A complicated nature of the contribution of different structural components of the polynucleotide to its stabilization was revealed by means of different parameters. Relationships between the change of conformational parameters corresponding to optimal values of energy for A- and B-families of nucleic acids were found.

DNA↗
PubMedDate not supplied

[Simulation of interactions in the co-planar nucleic acid base pairs using atom-atom potential functions].

Calculations of the energy of nucleic acid base interactions as a function of parameters determining mutual position of two bases in a plane have been performed. Atom-atom potential functions used include terms proportional to the first (electrostatic), sixth (or tenth for the atoms of hydrogen bond) and 12th power of interatomic distance. The calculations have shown the existence of 27 energy minima which correspond to the formation of co-planar pairs with two (or three for G : C pair) almost linear N--H...O and N--H...N hydrogen bonds. The positions of nitrogen bases bound by two hydrogen bonds in every crystal of nucleic acid components, in the complexes of polynucleotides and in tRNA are near to the positions in one of these minima. In addition for every pair there exist energy minima which correspond to the formation of one N--H...O or N--H...N and one C--H...O or C--H...N hydrogen bond. Energy behavior near minima have been investigated. The results of our calculations are in agreement with experimental data and with the calculations which employ quantum mechanical results.

Base Composition↗
PubMedDate not supplied

[Role of nonspecific complex formation in protein-nucleic acid recognition].

Combinatory mathematical model of equilibrium binding of recognising proteins to DNA has been considered. The expression for the ratio of specific and unspecific complex as the function of a number of nucleotides in DNA, a number of centers of recognition, concentration of recognising molecules and a code number have been obtained. The analysis of obtained expression for the repressor--operator system showed that binary code would preferable than quartic one. The specificity of binding corresponding to experimental results have been observed by the number of centers more than twenty, in the narrow interval of the energy value and by high limitation on the number of combinations of error centers.

Base Sequence↗
PubMedDate not supplied

[Possible conformations of nucleic acid fragments containing the base pair guanine:uracil].

By using classical potential functions, nonbound interaction energy calculations are carried out on the deoxydinucleoside phosphate complexes dUpdA:dUpdG and dUpdU:dGpdA. All dihedral and bond angles, except those of the nitrogen bases, are varied. On the basis of the calculations possible conformations of nucleic acid fragments containing G:U base pair are proposed. Dihedral angles of the conformations are close to those of regular Watson-Crick helices while interaction energies are 3-4 kcal/mole higher than that of A:U containing fragment conformations.

Base Composition↗
PubMedDate not supplied

[Molecular mechanisms of nucleic acid biosynthesis errors induced by alkylation of the nitrogen bases].

The possible pathways of nucleic acid synthesis errors induced by alkylation of the nitrogen bases are considered. Using the atom-atom potential method, intermolecular interaction energy is calculated for coplanar pairs containing a normal base and N- or O-methylated analogue. By analysing the calculation results in terms of the conception of recognition centers of template enzymes the base pairs, which may occur in nucleic acid biosynthesis, were found. The preferential arising of G : C leads to A : T transitions is explained by formation of m6G : T pair. m6G : A and methylated pyrimidine : pyrimidine pair formation is supposed to be the pathways of transversions. All the data available concerning DNA and RNA synthesis on templates containing methylated analogues are explained by formation of wobble-pairs, pairs with one of the nucleotides in syn-conformation and pairs with one H-bond and a short C--H ... O or C--H ... N contact.

Alkylation↗
PubMedDate not supplied

[Nuclear magnetic resonance study of C--H...O type hydrogen bonds in analogs of nucleic acid base].

Concentration and temperature dependence of nuclear magnetic resonance spectra of 1,3-dimethyluracil (m2 1,3Ura) in organic solvents has been investigated. The results indicate m2 1,3Ura dimer formation via C(6)--H...O hydrogen bond. In addition to that the formation of C--H...O H-bonds between solvent molecules and m2 1,3Ura take place. delta H of C---H...O H-bond formation between chloroform and m2 1,3Ura dimers have the value of about -2.5 and -2.0 kcal/mol, respectively. Interaction energy calculations by atom-atom potential functions for different types of m2 1,3Ura dimers are in good agreement with experimental data. The possible role of C--H...O H-bonds in intermolecular interactions and biological functions of nucleic acids are discussed.

Chloroform↗
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[Simulation of DNA conformation possibilities by means of nonbonded interaction energy calculations of complementary dinucleoside phosphate complexes].

Nonbonded interaction energy calculations were performed for complementary deoxydinucleoside phosphate complexes dApdA with dUpdU and dUpdA with dUpdA. All dihedral and bond angles but nitrogen base angles were the variables in minimization of energy. Complex conformations resembling A- and B-family double-helical conformations were recieved as a result of calculations when intramolecular interaction energy approach minima. Dihedral angles of one molecule of the complex may differ from corresponding angles of another by several degrees. Energy optimal complex conformations in other space regions of conformation parameters were found. Biological consequences of possible dihedral and bond angle changes of double stranded nucleic acids at interactions with other molecules are discussed.

Chemical Phenomena↗
PubMedDate not supplied

[Molecular mechanisms of spontaneous transversions and transitions].

Molecular mechanisms of spontaneous base substitutions during template directed nucleic acid synthesis have been considered. For this purpose calculations of interaction energy in various coplanar base pairs with approximately such glycoside bond positions as for Watson--Crick base pairs have been carried out by means of atom-atom potential function method. A number of this energy local minima which could be realized in double helix during template synthesis have been found. The calculation results permit to present purine-purine pair formation with transition of one of nucleotides to syn-conformation as the main transversion pathway and formation of wobble pairs UG and AC as the transition pathway. A possible contribution of interactions between base pairs and enzyme to fidelity of template synthesis have been evaluated. Calculation results are in accord with experimental data on spontaneous mutation frequencies of errors in nucleic acid synthesis in vitro.

DNA↗
PubMedDate not supplied

[The possible role of rare tautomers of DNA bases in mutagenesis: study of the effect of hydration on tautomeric equilibrium by the Monte-Carlo method].

Monte Carlo simulation of hydration of keto and enol tautomers of 9-methylguanine (G) and 1-methyluracil (U) has been performed in relation to a possible role of tautomer transitions of DNA bases in mutagenesis. The comparison of the simulation results with published experimental data and results of quantum mechanical computations leads us to conclusion about difference in the origins of keto-form prevalence in water solutions of G and U. Such a reason for uracil (thymine) is a greater intrinsic stability of keto tautomer while the more preferable hydration of keto form of G is the reason of its predominance. As a consequence, during biosynthesis less hydrophylic environment (as compared to water solution) can be a reason for guanine transition into enol form and can result in mispair formation. Such a mutation mechanism is of a minor probability through thymine (uracil) tautomerization.

DNA↗