The carbohydrate moiety of human chorionic gonadotropin: lack of competition with HCG for testicular receptors and anti-HCG-serum.
A glycopeptide fraction has been prepared from human chorionic gonadotropin (HCG) by digesting the reduced, S-carboxymethylated hormone with pronase and fractionating the digest by gel exclusion chromatography. The glycopeptide fraction was estimated to contain (w/w) 29% sialic acid, 31% hexose, 23% hexosamine, and 17% amino acids and/or peptides; thus, the glycopeptide mixture is 83% carbohydrate compared to intact HCG which is about 30% carbohdyrate. There was no cross-reactivity of the glycopeptide fraction with an antiserum directed against HCG. Also, when corrected for minimal non-specific effects, the fraction failed to displace 125I-HCG from a rat testicular preparation even when tested at a 10,000-fold (w/w) excess. Thus, any model involving carbohydrate effects in gonadotropin action must include the protein moiety as a necessary component.
D001667:Binding, Competitive; D006063:Chorionic Gonadotropin / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D003429:Cross Reactions; D006020:Glycopeptides / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D007106:Immune Sera; D008297:Male; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013737:Testis
D006063:Chorionic Gonadotropin; D006020:Glycopeptides; D007106:Immune Sera; D011956:Receptors, Cell Surface