Biochemical study of cardiac valvular tissue. The isolation of glycoproteins and proteoglycans from salt-insoluble materials of bovine heart valve

Abstract

The chemical nature of the various kinds of glycoproteins as well as proteoglycans in bovine heart valve were investigated. Two glycoproteins were isolated by collagenase digestion from the salt-insoluble matrix; the chemical composition of the sugar moieties were different from each other and both were unique in their amino acid composition. The remaining collagenase-insoluble materials were solubilized with 8 m area followed by 0.1 m 2-mercaptoethanol in 8 m urea. Proteoglycans and glycoproteins were separated using both urea- and mercaptoethanol-soluble products treated with cetylpyridinium chloride (CPC). Two corresponding glycoprotein fractions from CPC supernatants were obtained; there was a considerable difference in the chemical composition of both sugar and protein moieties and these results were remarkably different from collagenase-soluble glycoproteins. On the other hand, the CPC complexes which were separated into 2 m CaCl 2 extractable materials were mainly proteoglycans and unextractable residues. The residual fractions were completely solubilized in 4 m guanidine hydrochloride solution. Both fractions consisted mainly of glycoproteins which had similar chemical compositions. In addition, despite the large variation in sugar contents, the amino acid composition of these glycoproteins was very similar to that of “structural glycoprotein,” and “acidic structural protein” isolated by other workers.