Mk. Dowd et al., RELAXED-RESIDUE CONFORMATIONAL MAPPING OF THE 3 LINKAGE BONDS OF ISOMALTOSE AND GENTIOBIOSE WITH MM3(92), Biopolymers, 34(5), 1994, pp. 625-638
Isoenergy surfaces were calculated for the alpha- and beta-anomers of
isomaltose and gentiobiose, based on 46,656 conformers for each disacc
haride. Low-energy regions exist for each of the three staggered posit
ions about the C-5'-C-6' bonds, and known crystal structures lie in tw
o of these regions. As expected, the molecular partition function show
ed greater flexibility for these three-bond-linked disaccharides than
for comparable two-bond-linked structures. A model miniature crystal o
f gentiobiose accounts for most of the remaining structural difference
s between the modeled isolated molecule and the crystal structure. Bas
ed on models of isolated molecules of isomaltose and gentiobiose, the
predicted Boltzmann-weighted nmr coupling constants were satisfactory,
as were predicted optical rotations for gentiobiose. (C) 1994 John Wi
ley and Sons, Inc.