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 0-(alpha-D-mannopyranosyl)-alpha-D-mann opyranoside is calculated semiempirically as a function of the linkage dihedral angles phi (H1-C1-O1-C3') and psi (C1-O1-C3'-H3'). Compariso n with the observed optical rotation in aqueous solution indicates the existence of at least two conformers in solution, which implies a deg ree of linkage flexibility. The result is in agreement with some, but not all, calculated potential energy surfaces, and with recently publi shed nmr data. (C) 1994 John Wiley and Sons, Inc.