Молекулярная и электронная структуры фрагмента металлизированной ДНК-пары аденин-тимин с ионом цинка

Abstract

To study physical properties of fragments of metallic DNA (M-DNA), molecular and electronic structures and thermodynamic characteristics of the adenine-thymine pair with a Zn2+ ion (the ion was placed between nucleic acid bases) and of components forming this pair are calculated at the МР2/6–31 +G* level of theory. As well, the calculations were performed for adeni- ne-thymine-Zn2+-hydroxyl. It was revealed that the following bond lengths changed in investigated complexes: on the N3-C2-N1-C6-N10 fragment in the adenine, on С2-N3-C4-C5-C6-N1 fragment on the pyrimidine ring, and on C4-O8 in thymine, in comparison with neutral molecules. Charges on atoms changed at the same fragments. In the complexes calculated, the interaction energies of base pairs with Zn2+ are significantly higher than that of imino-proton with the AT pair or that of Zn2+ with its hydrate shell (6 water molecules). The HOMO and LUMO analyses of the ATZn+ triple complex and the AT pair showed the increase of sizes of the triple complex LUMO, which points to a possibility of the electron delocalization over the whole complex.