Molecular Dynamics Simulation of Sucrose in Aqueous and Dimethyl Sulfoxide Solution.

Abstract

Molecular dynamics simulations have been carried out to study the motion of a single sucrose molecule in two solvents, water and dimethyl sulfoxide at 300 K. Starting from a crystal structure of sucrose, no major conformational transitions are observed for the dihedral angles of the glycosidic linkage, nor are they observed for any of the hydroxymethyl groups in either of the solutions during 200 ps, the duration of the production part in both simulations. Hydroxyl groups usually show frequent transitions, except for those involved in hydrogen bonding between the two sugar residues in sucrose. Inter-residue hydrogen bonding is observed between O5g and H'6f for more than half of the simulation time and between Olf and H'2g for about half of the simulation time both in water and in dimethyl sulfoxide. Radial distribution functions were calculated between oxygens or hydroxyl protons of the solute and solvent oxygen atoms. Radial distribution functions typical of hydrogen bonding to solvent are observed for the hydroxyl groups of sucrose except for those involved in inter-residue hydrogen bonding, where coordination numbers are reduced. Translational diffusion constants were calculated from the simulations and were far sucrose 1.2 x 10(-5) cm(2) s(-1) in water and 0.13 x 10(-5) cm(2) s(-1) in dimethyl sulfoxide.