Molecular dynamics simulations of glycosides in aqueous solution

Molecular dynamics simulations for aq solutions of methyl-alpha- and -beta-D-glucopyranoside, galactopyranoside and talopyranoside have been carried out. A single molecule surrounded by 252 SPC water molecules was used under periodic boundary conditions. Preference for the gr and gg orientations for the hydroxymethyl groups in solution has been confirmed. Examination of the extent and pattern of hydrogen bonding between water and the sugar molecule hydroxyl groups showed that the galactose and glucose derivatives were substantially better hydrogen-bond donors at OH-2 and OH-4 than the respective ones of talose. Intramolecular hydrogen bonding involving OH-2 and OH-4 of the talosides persisted for some 40% of the 100 ps simulation time in water. The remarkably long retention times (on reversed-phase HPLC in pure water) of the talosides relative to the galactosides and glucosides were rationalised in terms of differing extents of hydration, intramolecular hydrogen bonding, and compatibility with the structure of water.