The potential energy surface of methyl 2-O-(α-D-mannopyranosyl)-α-D-mannopyranoside in aqueous solution: Conclusions derived from optical rotation

The optical rotation of methyl 2-O -(α-D -mannopyranosyl)-α-D -mannopyranoside is calculated semiempirically as a function of the linkage dihedral angles ? (H1-C1-O1-C2′) and ψ (C1-O1-C2′-H2′). Although the rotation calculated for the global energy minimum conformation found in several rigid-residue modeling calculations (?,ψ = ?40°,?20°) is in good agreement with the observed solution rotation, the observed rotation is also compatible with the limited flexibility inferred from more recent relaxed residue modeling calculations on a structurally related rhamnose disaccharide © 1994 John Wiley & Sons, Inc.