T. Yu. Nikolaienko¹, L. A. Bulavin¹, D. M. Hovorun^1,2

¹Taras Shevchenko Kyiv National University, Ukraine;
²Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv;
е-mail: tim_mail@ukr.net

Exhaustive conformational analysis of the 5′-deoxyadenylic acid molecule, has been carried out by the quantum-mechanical density functional theory method at the MP2/6-311++G(d,p) // DFT B3LYP/6-31G(d,p) theory level. As many as 726 of its conformations have been revealed with the relative gas phase Gibbs energies under standard­ conditions from 0 to 12.1 kcal/mole. It has been shown, that the energetically most favorable conformation has north sugar puckering and syn- orien­tation of the nitrogenous base and is stabilized by intramolecular O_P1H_P1∙∙∙N₃ and O_3′H∙∙∙O_P hydrogen bonds. Four conformations have been shown to have their geometry similar to that of AI-DNA and four – of BI-DNA. One conformer of the 5′-deoxyadenylic acid molecule is similar to its sodium salt hexahydrate structure in crystalline state resolved by the X-ray diffraction method and taken from literature. It is shown that effective charges of C_4′ and C_5′ atoms are the most sensitive to the molecule conformation ones. The role of the intramolecular OH∙∙∙N hydrogen bonds in formation of the 5′-deoxyadenylic acid molecule structure has been demonstrated.