Solution conformation of asparagine-linked oligosaccharides: .alpha.(1-2)-, .alpha.(1-3)-, .beta.(1-2)-, and .beta.(1-4)-linked units

Abstract

The solution conformation is presented for representatives of each of the major classes of asparaginyl oligosaccharides. In this report the conformation of .alpha.(1-3)-, .alpha.(1-2)-, .beta.(1-2)- and .beta.(1-4)-linked units is described. The conformational properties of these glycopeptides were determined by high-resolution 1H NMR in conjunction with potential energy calculations. The NMR parameters that were used in this analysis were chemical shifts and nuclear Overhauser enhancements. Potential energy calculations were used to evaluate the preferred conformers available for the different linkages in glycopeptides and to draw conclusions about the behavior in solution of these molecules. The linkage conformation of the Man.alpha.1-3 residues was not affected by substitution either at the 2-position by .alpha.Man or .beta.GlcNAc or at the 4-position by .beta.GlcNAc or by the presence of a bisecting GlcNAc on the adjacent .beta.Man residue.