Characterization of the high mannose asparagine-linked oligosaccharides synthesized by Schistosoma mansoni adult male worms

Abstract

This report describes the structures of the high-mannose-type N-linked oligosaccharides in glycoproteins synthesized by Schistosoma mansoni adult male worms. Adult male schistosomes were incubated in vitro in media containing either [2- 3H]mannose, [6- 3H]glucosamine or [6- 3H]galactose to allow metabolic radiolabeling of the oligosaccharide moieties of newly synthesized glycoproteins. Glycopeptides were prepared from the radiolabeled glycoproteins by digestion with Pronase and fractionation by chromatography on concanavalin A-Sepharose. Eleven percent of [ 3H]mannose incorporated into the schistosome glycopeptides was recovered in high mannose-type Asn-linked oligosaccharides which bound to the immobilized lectin. Upon treatment of [ 3H]mannose-labeled glycopeptide with endo- β- N-acetylglucosaminidase H, the high mannose-type chains were released and their structures were determined by high performance liquid chromatography, methylation analysis, acetolysis and exoglycosidase digestion. The major species of high mannose-type chains synthesized by S. mansoni adult males have the composition Man 7GlcNAc 2, Man 8GlcNac 2 and Man 9GlcNA 2. Structural analyses indicate that these oligosaccharides are similar to high mannose-type chains synthesized by mammalian cells.