Oleg S. Sukhanov, O. Shishkin, L. Gorb
Feb 1, 2008
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Journal
Structural Chemistry
Abstract
Molecular structure of complexes of guanine with 12, 13, 16, and 17 water molecules were calculated using B3LYP/6-311G(d,p) level of theory. Interaction with water results in some deformation of geometrical parameters of guanine, which can be described as contribution of zwitter-ionic resonant form into the structure of DNA base. Saturation of water binding sites within guanine creates possibilities for the formation of the N···H–O hydrogen bond where the nitrogen atom of amino group acts as proton acceptor. The NBO analysis of guanine–water interactions reveals that hydrogen bonds involving the N(3) and N(7) atoms of guanine represent a case of mixed N···H–O/π···H–O hydrogen bonds where contribution of π-system into total energy of interaction varies from 3% to 41%. This contribution significantly depends on orientation of the hydrogen atom of water molecule with respect to plane of purine bicycle and influence of neighboring water molecules.Graphical Abstract