A Comparative Study of the Glycosaminoglycan-Peptides Obtained After Degradation of Cartilage Proteoglycan by Different Proteinases, and Their use in the Characterization of Different Proteoglycans

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Abstract
Proteoglycan subunit was isolated from bovine nasal cartilage by extraction with 2 M CaCl2 and purified by CsCl-density gradient centrifugation. Proteolytic degradation of the proteoglycan by different commercially available proteinases was used to produce glycosaminoglycan-peptides of varying structures. Degradation products containing chondroitin sulfate were isolated by precipitation with cetylpyridinium chloride and their properties studied by Sepharose 4B chromatography, viscometry, agarose/polyacrylamide-gel electrophoresis, hexosamine analysis and amino acid analysis. The proteoglycan core protein may have short constant sequences at the points of attachment of the glycosaminoglycan chains and variable sequences between the chains. The length and composition of the variable sequences determine the susceptibility of each interchain-peptide to cleavage by a particular proteinase and account for the multiplicity of degradation products. These degradation products are characteristic of a particular core protein structure and can be used for comparing the structure of proteoglycans from different sources. This technique is illustrated by comparing the intact proteoglycan subunit and its proteolytic degradation products from bovine articular cartilage with their counterparts from bovine nasal cartilage. The smaller size of the proteoglycan subunits from articular cartilage was apparently due to degradation of a common core protein or to shorter chondroitin sulfate chains rather than to the synthesis of a different core protein.