Structure Determination of Glycolipids Using Two Dimensional Proton NMR Spectroscopy: Globoside

Abstract

High resolution 1 and 2 dimensional proton nuclear magnetic resonance (2D-NMR) spectra of the glycosphingolipid globoside (the P blood group antigen) were obtained at 500 MHz and 40-50% in C in dimethylsulfoxide-d6-deuterium oxide (98:2 vol/vol). Analysis of a scalar coupling correlated spectrum (SECSY) allows assignment of resonances to residue types. Analysis of the oligosaccharide anomeric proton signals in the 3-6 ppm region of the 2D nuclear Overhauser effect (2D-NOE) spectrum of globoside reveals inter-residue couplings that allow identification of glycosidic linkage interactions and hence a primary structure. The diversity of linkage types in globoside demonstrates that oligosaccharide sequence determination via 2D-NMR spectroscopy may be considered a general approach, regardless of the type of anomeric linkage involved. Measurement of the intra-oligosaccharide and inter-oligosaccharide NOE-couplings allows an estimation of the glycosidic interproton distances for each glycosidic linkage. These distances are shown to be consistent with current views of preferred glycosidic bond conformations.