title: [Quantum-chemical investigation of tautomerization ways of Watson-Crick DNA base pair guanine-cytosine].
abstract: A novel physico-chemical mechanism of the Watson-Crick DNA base pair Gua.Cyt tautomerization Gua.Cyt*<---->Gua.Cyt<---->Gua*.Cyt (mutagenic tautomers of bases are marked by asterisks) have been revealed and realized in a pathway of single proton transfer through two mutual isoenergetic transition states with Gibbs free energy of activation 30.4 and 30.6 kcal/mol and they are ion pairs stabilized by three (N2H...N3, N1H...N4- and O6+H...N4-) and five (N2H...O2, N1H...O2, N1H...N3, O6+H...N4- and 06+H...N4-) H-bonds accordingly. Stable base pairs Gua-Cyt* and Gua*.Cyt which dissociate comparably easy into monomers have acceptable relative Gibbs energies--12.9 and 14.3 kcal/mol--for the explanation of the nature of the spontaneous transitions of DNA replication. Results are obtained at the MP2/6-311++G(2df,pd)//B3LYP/6-31 1++G(d,p) level of theory in vacuum approach.
authors.forename: O O
authors.initials: OO
authors.lastname: Brovarets'
authors.forename: D M
authors.initials: DM
authors.lastname: Hovorun
mesh_terms: D001482:Base Composition / Q000235:genetics; D020029:Base Pairing / Q000235:genetics; D019295:Computational Biology / Q000379:methods*; D003596:Cytosine / Q000737:chemistry*; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004261:DNA Replication / Q000235:genetics; D004735:Energy Transfer; D006147:Guanine / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011789:Quantum Theory
chemical_list: D006147:Guanine; D003596:Cytosine; D004247:DNA