Biopolym. Cell. 2010; 26(4):295-298.
Molecular Biophysics
Stability of mutagenic tautomers of uracil and its halogen derivatives: the results of quantum-mechanical investigation
1, 2Brovarets' O. O., 1, 3Hovorun D. M.
  1. Institute of Molecular Biology and Genetics, NAS of Ukraine
    150, Akademika Zabolotnoho Str., Kyiv, Ukraine, 03680
  2. Taras Shevchenko National University of Kyiv
    64/13, Volodymyrska Str., Kyiv, Ukraine, 01601
  3. Institute of High Technologies,
    Taras Shevchenko National University of Kyiv
    2, korp.5, Pr. Akademika Hlushkova, Kyiv, Ukraine, 03022

Abstract

Aim. To investigate by quantum-mechanical methods the uracil (Ura) intramolecular tautomerisation and effect of changing the thymine (Thy) methyl (Me) group with halogen on this process. Methods. Non-empirical quantum mechanics, analysis of the electron density by means of Bader’s atom in molecules (AIM) theory and physical-chemical kinetics were used. Results. It has been established for the first time that the substitution of halogen (Br, F, Cl) for thymine Me-group has practically no effect on the main physical-chemical characteristics of the intramolecular tautomerisation. At the same time, the energy of Ura tautomerisation increases by 3.08 kcal/mole in comparison with the corresponding value for Thy under standard conditions. Conclusions. Thus, 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 genom from the point of view of its adaptation reserve. A mutagenic action of the Ura halogen derivatives is not directly associated with their tautomerisation.
Keywords: DNA bases, uracil, mutagenic tautomers, uracil halogenation, lifetime, intramolecular tautomerisation, quantum-mechanical calculations

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