Immunodiffusion, immunoelectrophoresis, SDS-polyacrylamide gel electrophoresis, polyacrylamide gel electrophoresis, ultracentrifugation analysis, and gel permeation chromatography in chaotropic and detergent mediums showed that the human seminal plasma obtained and stored in the usual way is mainly composed by heterodispersed glycoproteins of low molecular weight. The glycoprotein components of the human seminal plasma which do not interact specifically with concanavalin A (con A) were separated by column chromatography on Con A-Sepharose according to nonspecific ion exchange and hydrophobic interactions with the protein. The carbohydrate composition of the glycoproteins and the existence of the N-acetylgalactosaminylserine (or threonine) linkage, as well as their aggregation properties show that they are mucin-type glycoproteins. They resulted "immunologically pure" although the carbohydrate chains show the structural heterodispersion usually found in mucins. The glycoproteins have a common structural pattern for the terminal nonreducing, determinant-bearing sequences of their oligosaccharide chains which, together with the low molecular weights and the known fact that mucus secretions of normal cells contain only one or two types of glycoproteins, suggest that they are fragments produced by endogenous proteolytic degradation of a native mucin.
Sperm-surface glycopeptides were obtained from intact sperm membranes after proteolytic release by different enzymatic treatments such as autoproteolysis, trypsin, papain and pronase. Glycopeptides were isolated, their properties and composition were examined, and their monosaccharide and amino acid constituents were characterized. The monosaccharides identified were fucose, mannose, galactose, N-acetylglucosamine, and N-acetylgalactosamine, which form part of more than one type of oligosaccharide units. Autoproteolytic treatment mainly provided O-glycosidic type oligosaccharides, while a mixture of O-and N-glycosidic oligosaccharides was obtained in variable proportions when treated with trypsin, papain or pronase. The highest degree of peptide cleavage was obtained with pronase. Despite the higher yields reached with trypsin, these glycopeptides contain the lowest percentage of oligosaccharide chains. Proteolytic treatment provides a simple, rapid procedure for the isolation of glycopeptides from the sperm surface.
Affinity chromatography on Concanavalin-A Sepharose, followed by gel filtration and hydrophobic interaction chromatography, permits the isolation of low molecular weight N-glycosidically linked oligomannosidic glycopeptides (MGp) from the autoproteolysis products of human seminal plasma. The monosaccharide composition of MGp showed only mannose, N-acetylglucosamine and a small amount of galactose. Structural studies were carried out by methylation analysis and chromium trioxide oxidation, and results were consistent with the structures accepted for high-mannose N-glycans. MGp was capable of inhibiting the sperm acrosomal exocytosis mediated by sperm-surface receptors. These data suggest that MGp act as a "decapacitation" factor preventing premature sperm exocytosis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.