3-DIMENSIONAL HETERONUCLEAR NMR TECHNIQUES FOR ASSIGNMENT AND CONFORMATIONAL-ANALYSIS USING EXCHANGEABLE PROTONS IN UNIFORMLY C-13-ENRICHEDOLIGOSACCHARIDES

We present heteronuclear three-dimensional gradient-NMR techniques for the resonance assignment of exchangeable (-OH and -NH) protons in uni formly C-13 isotopically enriched oligosaccharides and for the measure ment of H-1-H-1 nuclear Overhauser enhancements involving these proton s. These techniques are derived from conventional HOHAHA-HSQC and NOES Y(ROESY)-HSQC experiments, and are illustrated in application to a sam ple of uniformly C-13-enriched Gal beta 1-4GlcNAc and demonstrate that a total of 35 ROEs involving exchangeable protons can be detected and assigned. We present a quantitative analysis of these ROEs that can o nly be accommodated in a model of the solution behaviour of the oligos accharide that involves considerable internal motion.