STUDIES ON GLYCOSPHINGOLIPIDS OF FRESHWATER BIVALVES .5. STRUCTURE OF A NOVEL CERAMIDE OCTASACCHARIDE CONTAINING MANNOSE-6-PHOSPHATE FOUND IN THE BIVALVE, CORBICULA-SANDAI

A ceramide octasaccharide containing mannose-6-phosphate was isolated from the freshwater bivalve Corbicula sandai by solvent fractionation, followed by two types of silicic acid colunm chromatography, and finally QAE-Sephadex column chromatography. The structural analysis involved the following steps. (a) Gas-liquid chromatography of the component sugars, fatty acids, and long-chain bases. (b) Degradation with HCl and HF to elucidate the sugar sequence. (c) Permethylation analysis coupled with GC-MS to identify the positions of the glycosidic linkages between the sugar units. (d) Chromium trioxide oxidation to determine the anomeric configuration. (e) Smith degradation to determine the site of linkage of the ethanolamine residue.The structure of this novel glycolipid was determined to be: 4-O-MeGalp(β1→3)-GalNAcp(β1→3)Fucp(α1→4)GlcNAcp(β1→2)Manp(αl→3)[Xylp(α1→2)][2'-aminoethyl-phosphoryl(→6)]Manp It is very interesting that fucose was found to be internally linked in this sugar chain. To our knowledge, this is the first example of internal fucose in a glycolipid. The ceramide moiety consisted of normal saturated fatty acids, among which stearic acid was predominant, and contained C16- and C18-4-sphingenine as the major long-chain bases. © 1979 By The Journal Of Biochemistry.