M. M. Ilchenko

Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv;
e-mail: m.m.ilchenko@imbg.org.ua

Geometric and electronic structure of D-glucosamine complexes with Ca²⁺ was studied with DFT (Density Functional Theory) method at B3LYP/6-31G(d) level of the theory. It was shown that in the most probable complex the cation interacts directly with oxygen atom of glucopyranose ring. The presence of six water molecules in the first hydration sphere of Ca²⁺ does not substantially affect the order of energetic favorability of complexes formed by different modes of cation coordination. Calculations within the frame of PCM model demonstrated that in aqueous solution the only stable complexes are those where Ca²⁺ interacts directly with glucopyranose ring oxygen. This interaction between the cation and glucosamine may be accompanied by deprotonation of О1Н hydroxyl group and simultaneous protonation of amino group.

Keywords: complexation, D-glucosamine, DFT method, hydrated environment, intermolecular interaction