SOLUTION CONFORMATION OF LAMINARIBIOSIDE AND (1-]3)-BETA-D-GLUCAN FROM OPTICAL-ROTATION

A chiroptical method of conformational analysis is applied to linear (1 --> 3)-beta-D-glucans and the dimeric analogues beta- and alpha-laminaribioside. The method is based on a recently developed semiempirical calculational model for saccharide optical activity. We conclude that disaccharide conformational energy maps in the literature represent the effective potential energy surface in aqueous solution well. The positive optical rotation observed with long chains in dilute alkaline solution is not characteristic of any single-chain conformation, and must reflect chain association.