Brovarets O. Physico-chemical nature of the spontaneous and induced by the mutagens transitions and transversions

Novel physico-chemical models of spontaneous and induced by chemical mutagens, namely the analogues of nucleobases, transitions and transversions were elaborated and analyzed. These models can adequately explain the results of some molecular biolologic experiments. Physical model of the recognition of Watson-Crick base pairs by DNA-binding proteins from the major groove side was elaborated.This model allows the inhibition of biosynthesis of mispairs formed by both rare and canonical tauto-mers of DNA bases. It was shown at the level of base pairs that ionization mechanism of the genetic mu-tations can't be adequately explained from the physico-chemical point of view. We have investigated all possible purine-purine mispairs containing template base only in anti-configuration. It was established that only those of them which can easily adopt Watson-Crick shape, cause spontaneous transversions arising. The shift of tautomeric equilibrium of xanthine and hypoxanthine bases in the triple complexes Na+Xan/HypCH3COO- to high-energy tautomers, so-called "hidden struc-tures", was found.