Biopolymers and cell. 1999; 15 (5): 422 - 431

Influence of methylalion and interactions with amino acid carboxylic group on UV spectra of purine nucleotide bases and nucleosides in dimethylsulfoxide. 1. Adenine

A. V. Stepanyugin, I. M. Kolomiets, S. P. Samijtenko

UV absorption spectra of adenine, adenosine and a number of their methyl derivatives were studied in DMSO. Essential changes in adenine UV spectra tinder methylation at positions I and 3, as well as in adenosine at position 1, reflect significant rebuilding of adenine purine ring. Ade and m Ade were shown to form complexes with deprotonated amino acid carboxylic group (carboxylate-ion) through two H-bonds involving amino group and the N7H imino group, the N9H •* N7H tautomeric transition is therewith initiated just by interaction with carboxylate-ion. Substantial changes in m Ade, m A and m Ade UV spectra under interactions with neutral amino acid carboxylic group are interpreted as a result of proton transfer from amino acid to bases.