Determination of glycopeptide primary structure by 360-MHz proton magnetic resonance spectroscopy.

A detailed analysis of the proton magnetic resonance spectral parameters for the anomeric and C2 hydrogen resonances of 63 different glycopeptides and oligosaccharides of known structure reveals a general method for the determination of the primary structure of glycopeptides for most currently known classes of structures. In particular, a two-dimensional display formed by plotting mannosyl C1-H vs. C2-H chemical shifts demonstrates that these pairs of values are sensitive to long-range perturbation by remote substitution by hexoses as well as to direct substitution effects. A total of 41 Cl-H/C2-H chemical shift clusters have been defined which characterize unique structural microenvironments. On the basis, the sequence and branching pattern for most structures can be derived. Corroborative evidence is obtained from an examination of the chemical shifts of the galactosyl and N-acetylglucosaminyl anomeric hydrogens as well as other features of the spectrum.