Biopolymers and cell. 2010; 26 (4): 295 - 298
Stability of mutagenic tautomers of uracil and its halogen derivatives: the results of quantum-mechanical investigation
O. O. Brovarets’1, 2, D. M. Hovorun1, 3
1Institute of molecular biology and genetics NAS of Ukraine 150, Zabolotnogo Str, Kyiv Ukraine, 03680
2 National Taras Shevchenko University of Kyiv, 64, Volodymyrska Str, Kyiv, Ukraine, 01033
3Institute of High Technologies , 2, Academician Glushkov Avenue, Building 5, Kyiv, Ukraine, 03022
Aim. To investigate using the quantum-mechanical methods uracil (Ura) intramolecular tautomerisation and the effect of the thymine (Thy) methyl (Me) group substitution by the halogen on that process. Methods. Non-empirical quantum mechanic, analysis of the electron density by means of Bader’s atom in molecules (AIM) theory and physicochemical kinetics were used. Results. For the first time it has been established that the substitution of thymine Me-group for the halogen (Br, F, Cl) has practically no effect on the main physico-chemical characteristics of intramolecular tautomerisation. At the same time, the energy of Ura tautomerisation increases for 3,08 kcal/mol in comparison with corresponding value for Thy under standard conditions. Conclusions. So, Thy, unlike Ura, is obviously able, as a canonical DNA nucleotide base, to provide together with Ade, Gua and Cyt an acceptable mutability degree of the genome from the point of view of its adaptation reserve. Mutagenic action of the Ura halogen derivatives is not directly associated with their tautomerisation.
Key words: DNA bases, uracil, mutagenic tautomers, uracil halogenation, lifetime, intramolecular tautomerisation, quantum-mechanical calculations.