Glycopeptides from the egg jelly coat of the toad Bufo vulgaris

Abstract

1. Glycopeptides isolated by exhaustive pronase digestion from the egg jelly coat of toad, Bufo vulgaris, were separated by DEAE-cellulose chromatography into two fractions. These fractions each gave a single band when they were subjected to electrophoresis on cellulose acetate strips. The glycopeptides behaved as a kind of "macroglycopeptide" on gel chromatography. 2. The glycopeptide fractions contained as sugar components galactosamine, glucosamine, galactose, fucose and N-acetylneuraminic acid. The amino acid composition was characterized by the presence of threonine and serine, which accounted for approximately 70% of the total amino acids. 3. Large amounts of galactosamine, threonine and serine were destroyed by treatment with alkali, indicating that the carbohydrate-peptide linkage in the glycopeptides is mostly an O-glycosidic bond between N-acetylgalactosamine and the hydroxy groups of threonine and serine.