Carbohydrates of the Surface of the Normal Human Spermatozoon

Abstract

Autoproteolysis of human spermatozoa produces oligopeptides with oligosaccharide chains of the N-glycosidic-linked type that are released from the "surface exposed" parts of glycoproteins. The products eluted in the previous washing of the spermatozoa have the same composition and solubility characteristics as the oligopeptides from the digestion. This suggests that autoproteolysis is a constant process that normally occurs on the spermatozoa membrane. The cytochemical characterization and localization of the N-glycosidic-linked oligosaccharide receptors on the human spermatozoa membrane after digestion, in the presence or absence of seminal plasma, indicates that only part of the oligosaccharides are cleaved. Their distribution on the different zones of the spermatozoon changed as the probability of detecting these receptors in the intermediate segment increased after proteolysis; this indicates that in this zone the receptors are cryptic ones that become exposed by the action of the proteolytic enzymes. In the presence of seminal plasma most receptors on the acrosome are eliminated.

Proteolytic release and partial characterization of human sperm-surface glycopeptides

“…After 1-h incubation with pronase, the percentage of Trypan blue-positive sperm increased by 18%. Digestion of sperm for a prolonged time with no disintegration of cells was previously observed by Mazzini et al (6). Samples obtained from the above treatments were isolated and studied.…”

“…Sperm antigen preparations are difficult to deal with because of the somewhat rigid sperm cell membrane that resists the usual solubilization methods. For the isolation of glycopeptides we used autoproteolysis, a technique which has been previously demonstrated to be useful (6). Other types of proteolytic enzymatic degradation were also investigated, such as trypsin and papain which have a more defined action, and pronase which has a wide specificity of action, cleaving glycosylated proteins of the membrane surface (18).…”

“…Autoproteolysis of normal human sperm produces peptides with oligosaccharide chains of the N-glycoside-linked type that are released from the surface-exposed parts of the glycoproteins. Cytochemi-cal characterization and localization of the N-glycoside-linked oligosaccharide receptors indicated that some are cryptic ones that become exposed by the action of proteolytic enzymes, and most receptors on the acrosome are eliminated when digestion is carried out in the presence of seminal plasma (6).…”

“…Human sperm membrane from normal donors was examined and its macromolecular components were isolated and partially characterized (6). Autoproteolysis of normal human sperm produces peptides with oligosaccharide chains of the N-glycoside-linked type that are released from the surface-exposed parts of the glycoproteins.…”

“…Oligosaccharides are involved in the immunology of sperm and reproduction (1)(2)(3)(4)(5)(6)(7) and play a significant role in the spermoocyte interaction (8). Oligosaccharides constitute a singular source of biological relevant compounds for the knowledge of structural features of sperm cell membrane or any cell membrane.…”