Glycosidic Torsional Motions in a Bicelle-associated Disaccharide from Residual Dipolar Couplings

An analysis of torsional motions about glycosidic bonds in a disaccharide is undertaken using residual dipolar coupling measurements and selective immobilization of the reducing end sugar to provide a suitable motional reference. The immobilization is accomplished by using the short chain of an alkyl glycoside to anchor the disaccharide to a bilayer medium aligned in magnetic field. Motions about the β-(1−4) linkage of the n-butyl-4-O-β−d-galactopyranosyl-α−d-mannopyranoside are shown to be substantial (±40°) and in good agreement with predictions of a fully solvated molecular dynamics simulation.