THE ROLE OF HYDROGEN-BONDING IN CARBOHYDRATES - MOLECULAR-DYNAMICS SIMULATIONS OF MALTOSE IN AQUEOUS-SOLUTION

Molecular dynamics simulations of maltose in two different conformations in vacuum and aqueous (TIP3P) solution have been used to examine the types of hydrogen bonds made by this carbohydrate molecule. Maltose was found to be extensively hydrogen bonded to solvent molecules in aqueous solution, and these hydrogen bonds were found to have potential conformational consequences. The exchange of an intramolecular O2-O3' hydrogen bond found in the crystal structure for hydrogen bonds to solvent was observed to produce significant changes in the solvation of the sugar molecule. Solvation was found to increase root mean square conformational fluctuations, in contrast to the results found in a previous simulation of a mannose dimer in aqueous solution. A substantial fraction of the first hydration layer water molecules around the polyfunctional maltose solute was found to make simultaneous hydrogen bonds to more than one sugar hydroxyl group. The nature and extent of the conformational effects of solvation in model systems were found to be sensitive to the molecular mechanics force fields used.