Biopolymers and cell. 2003; 19 (5): 463 - 466

Fixation of xanthine prototropic tautomers by methyl group does not practically change their relative energy: a DFT quantum-chemical investigation

M. O. Platonov, S. P. Samijlenko, D. M. Hovorun

The adequacy of determination of tautomeric equilibrium constants for isolated nucleotide bases using their corresponding methyl substituted derivatives has been confirmed with an example of prototropic tautomerism of xanthine. Non-empirical quantum chemical calculation at the B3LYP/6-31J++G(d, p) level of theory has been applied. The method limits are outlined especially for solutions in specific solvents.