A REINVESTIGATION TOWARDS THE CONFORMATION OF METHYL HA-D-MANNOPYRANOSYL-(1-]6)-ALPHA-D-MANNOPYRANOSIDE BY A COMBINED ROE AND MOLECULAR-DYNAMICS ANALYSIS

Conformational analysis of alpha-D-Man-p-(1 --> 6)-alpha-D-Man p1-OMe, by a combination of extensive molecular dynamics calculations in wate r and ROE buildup series, afforded two main minima, namely, phi/psi = 95/ - 178 and phi/psi = 140/ - 185. Transitions between these minima a re observed, which have not previously been demonstrated using other a pproaches. In contrast to literature data for the glycosidic linkage, describing equal populations of both the gg and the gt rotamers, it wa s found that the gg conformer is present to ca. 96%. The non-reducing mannosyl unit showed approximately a 1:1 ratio for the gg:gt equilibri um, in accordance with earlier reports.