title: Radioimmunochemical evidence for a role of carbohydrate in antigenic determinant(s) on human liver alpha-L-fucosidase.
abstract: A competitive-binding radioimmunoassay method was employed to investigate the role of carbohydrate in antigenic determinant(s) of human liver alpha-L-fucosidase. Competition curves were used to quantify the concentrations of competitors needed to cause 30% inhibition of the precipitation of 125I-labelled alpha-L-fucosidase. The isoelectric forms of alpha-L-fucosidase, which are related by sialic acid residues, were separated preparatively and used as competitors in the radioimmunoassay. A pattern of increasing effectiveness as competitors with increasing acidity of the forms was found, suggesting that sialic acid may be involved in the antigenic determinant(s) of alpha-L-fucosidase. Specificity was exhibited when sugar and sugar derivatives were used as competitors in the radioimmunoassay: a 51-fold range of competitive ability was found, and sialic acids (N-acetylneuraminic acid and N-glycollylneuraminic acid) and colominic acid (a polymer of N-acetylneuraminic acid) were the best competitors. The results of our studies suggest that carbohydrate contributes to antigenic determinant(s) of alpha-L-fucosidase and that sialic acid is probably the major sugar involved.
mesh_terms: D001667:Binding, Competitive; D002241:Carbohydrates / Q000276:immunology*; D000939:Epitopes / Q000276:immunology*; D006801:Humans; D007525:Isoelectric Focusing; D008099:Liver / Q000201:enzymology*; D011863:Radioimmunoassay; D012794:Sialic Acids / Q000276:immunology; D005644:alpha-L-Fucosidase / Q000276:immunology*
chemical_list: D002241:Carbohydrates; D000939:Epitopes; D012794:Sialic Acids; D005644:alpha-L-Fucosidase