Water-Soluble Glycosphingolipids of Dog Gastric Mucosa. Characterization of a Branched Ceramide Heptasaccharide

Abstract

Two glycosphingolipids, the carbohydrate portion of which consisted of galactose, glucose and N-acetylgalactosamine, have been isolated from the aqueous phase of buffered tetrahydrofuran extract of dog gastric mucosa. The structures of these glycolipids were identified by partial acid hydrolysis, sequential degradation with specific glycosidases and methylation analysis. The structure of glycolipid I (GalNAcα1→3GalNAcβ1→3Galα1→4Galβ1→4Glc→ceramide) was found to be identical to that of Forssman hapten. The branched structure of glycolipid II, as determined by the combination of enzymatic degradation and comparison of the permethylation products of the enzyme-degraded compounds, is proposed to be: