THE POTENTIAL-ENERGY SURFACE OF METHYL O-(ALPHA-D-MANNOPYRANOSYL)-ALPHA-D-MANNOPYRANOSIDE IN AQUEOUS-SOLUTION - CONCLUSIONS DERIVED FROM OPTICAL-ROTATION

The optical rotation of methyl O-(alpha-D-mannopyranosyl)-alpha-D-mann opyranoside is calculated semiempirically as a function of the linkage dihedral angles phi (H1-C1-O1-C2') and psi (C1-O1-C2'-H2'). Although the rotation calculated for the global energy minimum conformation fou nd in several rigid-residue modeling calculations (phi,psi = -40 degre es,-20 degrees) is in good agreement with the observed solution rotati on, the observed rotation is also compatible with the limited flexibil ity inferred from more recent relaxed residue modeling calculations on a structurally related rhamnose disaccharide (C) 1994 John Wiley and Sons, Inc.