Biopolymers and Cell. 2010; 26 (5): 398-405
Is there adequate ionization mechanism of the spontaneous transitions? Quantum-chemical investigation
O. O. Brovarets’1, 2, R. O. Zhurakivsky1, D. M. Hovorun1, 2
1Institute of Molecular Biology and Genetics NAS of Ukraine; 150, Akademika Zabolotnogo Str., Kyiv, Ukraine, 03680
2Institute of Íigh Òechnologies, Taras Shevchenko National University of Kyiv; Pr. Akademika Hlushkova 2, korp.5, Kyiv, 03127, Ukraine
Aim. To investigate theoretically the adequacy of the ionization mechanism of the spontaneous transitions appearance, using simple molecular models – DNA base pairs, one of which is ionized, and electroneutral and ionized DNA-like conformers of canonical nucleosides. Methods. Non-empirical quantum chemistry, physicochemical kinetics and analysis of the electron density by means of Bader’s atoms in molecules (AIM) theory were used. Results. It is established at base pairs that the ionization mechanism of transitions origin doesn’t imply any advantages in comparison with other mechanisms described in literature. However, the protonation/deprotonation of base in any canonical nucleoside significantly perturbs DNA-like conformations of the latter. Conclusions. The ionization mechanism can’t explain entirely the nature of the spontaneous transitions.
Keywords: spontaneous transitions, ionization mechanism, mismatched DNA base pairs, hydrogen bonds, quantum-chemical calculations.