A reinvestigation towards the conformation of methyl α-d-mannopyranosyl-(1 → 6)-α-d-mannopyranoside by a combined ROE and molecular dynamics analysis

Conformational analysis of α-d-Man p-(1 → 6)-α-d-Man p1-OMe, by a combination of extensive molecular dynamics calculations in water and ROE buildup series, afforded two main minima, namely, gf/ψ = 95/−178 and gf/ψ = 140/−185. Transitions between these minima are observed, which have not previously been demonstrated using other approaches. In contrast to literature data for the glycosidic linkage, describing equal populations of both the gg and the gt rotamers, it was 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 equilibrium, in accordance with earlier reports.