Hydration at glycosidic linkages of malto- and cello-oligosaccharides in aqueous solution from molecular dynamics simulation: Effect of conformational flexibility

We have carried out molecular dynamics simulation of malto- and cello-oligosaccharides from monomer to hexamer in two thousand TIP3P water molecules. Malto- and cello-oligosaccharides are both composed of d-glucopyranoses, but have different conformational flexibility at their glycosidic linkages; the latter is more rigid than the former. The purpose of this paper is to investigate effect of the conformational flexibility at glycosidic linkages on hydration states in aqueous solution. We investigate the hydration state of water around the saccharides. The number of hydrating water molecules was approximately the same between malto- and cello-oligosaccharides. However, water molecules hydrogen-bonded with more than two sugar oxygen atoms were 1.3∼1.5 times greater in cello- than malto-oligosaccharides. In addition, the double hydrogen-bonded water is more abundant around glycosidic linkages in cello- than malto-oligosaccharides. The rigid glycosidic linkage of cello-oligosaccharide leads to more abundant water molecules bridging sugar oxygens at glycosidic linkages than malto-oligosaccharides.