Biopolymers and cell. 2010; 26 (1): 72 - 76
How stable are the mutagenic tautomers of DNA bases?
O. O. Brovarets’1,2, D. M. Hovorun1
1Institute of Molecular Biology and Genetics NAS of Ukraine, 150, Academician Zabolotnogo Str., Kyiv, Ukraine, 03680
2National Taras Shevchenko University of Kyiv 64, Volodymyrska Str, Kyiv, Ukraine 01033
Aim. To determine the lifetime of the mutagenic tautomers of DNA base pairs through the investigation of the physicochemical mechanisms of their intramolecular proton transfer. Methods. Non-empirical quantum chemistry, the analysis of the electron density by means of Bader’s atom in molecules (AIM) theory and physicochemical kinetics were used. Results. Physicochemical character of the transition state of the intramolecular tautomerisation of DNA bases was investigated, the lifetime of mutagenic tautomers was calculated. Conclusions. The lifetime of the DNA bases mutagenic tautomers by 3–10 orders exceeds typical time of DNA replication in the cell (~103 s). This fact confirms that the postulate, on which the Watson-Crick tautomeric hypothesis of spontaneous transitions grounds, is adequate. The absence of intramolecular H-bonds in the canonical and mutagenic tautomeric forms determine their high stability.
Keywords: testosterone, ethyniltestosterone, quantum-chemical density functional theory, vibrational IR spectra.