Studies in immunochemistry. 21. The products of the degradation of blood-group-specific substances by ficin and papain

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Abstract
The specific blood-group mucopolysaccharides were incubated with crystalline ficin or papain and the products of proteolysis examined. The mucopolysaccharides were broken down essentially into 2 kinds of macromolecular''fragments and a small amount of diffusible peptide material. The larger of the decomposition products possessed a few per cent only of the serological activity of the original substance when the activity was measured by the hemagglutination-inhibition test. The smaller of the 2 fragments had considerably less activity than that of the larger one. The qualitative composition of the carbohydrate moiety of the decomposition products was identical with, and the quantitative composition close to, that of the original substance. The quantitative amino acid composition of the products of the proteolytic decomposition of the specific mucopolysaccharides showed they were not identical with those of the original substance, or with each other. The evidence suggests that the amino acids are not evenly distributed throughout the amino acid-containing moiety in the orignial specific mucopolysaccharides.