Biopolymers and cell. 1997; 13 (2): 127 - 134

A structural isomerism of nucleotide bases: AMI calculation

D. M. Hovorun

The investigation on physico-chemical features of the structural isomerism of free canonical nucleotide bases by the semiempirical quantum-chemical AMI method has issued in two interesting from the point of view of their potential biological significance results. It was elucidated that only two complementary bases adenine and thymine are energetically the most stable structural isomers in their families, moreover, unlike the other bases the energetic gap between the lowest adenine structural isomer and the next one in the family (which have different ability to code ) is of the most high value (5.3 kkal/mol). Furthermore, it was established that the mechanism of mutual transformation of «enantiomers» — of isomers which include amino group changes from an inverse-planar to rotational under amino group transition to eight position of imidazolyc cycle. A wide range of biological problems appeares which we succeeded to explains basing on the results obtained, they concern molecular evolution and genome evolution as well.