title: Recent advances in structural analysis of gangliosides: primary and secondary structures.
abstract: High-field (500 MHz) proton NMR has been used to elucidate the primary and secondary structures of glycosphingolipids (GSLs). Using 2-D J-correlated spectroscopy (2-D SECSY) which establishes scalar couplings of protons, the monosaccharide composition, anomeric configuration and aglycon structures of a GSL can be established. 2-D nuclear Overhauser effect spectroscopy (2-D NOE) then establishes through-space intra- and inter-residue couplings of cross-relaxing protons. We have found that each anomeric proton is involved in NOE couplings with inter- and intra-residue protons. The inter-residue coupling, resulting from interaction of protons across the glycosidic linkage, establishes the n-1 sugar residue and specific glycosidation site to which the n-residue is linked. When such information is known for each residue and is combined, the sequence of the core oligosaccharide is obtained. The sialylation-induced glycosidation shift is then used to establish the site of sialic acid residue attachment in a ganglioside molecule. We have also observed that the anomeric proton inter-residue NOE couplings can be used to suggest the preferred conformation of an oligosaccharide. We have found that the oligosaccharide residue of globoside exists in a unique and rather rigid conformation which could be stabilized by hydrogen bonds and van der Waals interactions. Since GSLs are known to have a receptor role and are implicated in cell-cell recognition, enzyme-substrate interaction and antigen-antibody interaction, the determination of their conformation should be useful in understanding their biological functions.
mesh_terms: D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005678:G(M2) Ganglioside; D005732:Gangliosides; D005915:Globosides; D006027:Glycosides / Q000032:analysis; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D009844:Oligosaccharides / Q000032:analysis
chemical_list: D005732:Gangliosides; D005915:Globosides; D006027:Glycosides; D009844:Oligosaccharides; D005678:G(M2) Ganglioside