Molecular dynamics simulation for β-1,3-D-glucan in aqueous solutions: Attachment of one side chain induces an entire structural change

β-1,3-D-glucans form a right-handed 6, triple helix in water, and some of them have side chains, generally, consisting of β-1,6-glucose. Since the side chains can provide hydrophilicity to the molecule, the conformation and other physical properties can be drastically changed by introducing the side chain. To understand the side chain effect from the molecular level, we attached one β-1,6 side chain to a β-1,3-D-glucan main chain consisting of 19 D-glucose units, and carried out molecular dynamics (MD) simulations in water. The calculation showed that the attachment of the side chain induced the change of helical pitch, hydrogen bonding type, and the bending of the main chain for β-1,3-D-glucan structure. The water molecules neighboring the side chain were bound with hydrogen bonds rather tightly and the mobility was more reduced than that of other water molecules.