PREPARATION OF GLYCOPEPTIDES FROM BOVINE SUBMAXILLARY MUCIN BY CHEMICAL DEGRADATION

The disaccharide side chains (85% of them) of bovine submaxillary mucin were cleaved by alkali through a β-elimination reaction. The resulting peptide contained unsaturated amino acids at most of the original serine and threonine positions. Hydrolytic scission of the 2-aminopropenoic acid residues was carried out by heating at 100° for 1 hr at pH 2.2, but cleavage did not occur at 2-amino-3-butenoic acid residues. Gel filtration of this material resulted in the separation on Sephadex G-25 of a glycopeptide fraction which was shown to have a molecular weight of 3000. This glycopeptide accounted for 40% by weight of the original bovine submaxillary mucin and had a relative amino acid composition equivalent to bovine submaxillary mucin and alkali-treated bovine submaxillary mucin; it still contained one disaccharide side chain. This suggests the existence of repeating sequences of about 28 amino acids in bovine submaxillary mucin. © 1969, American Chemical Society. All rights reserved.