The isolation of two types of collagen from embryonic bovine epiphyseal cartilage.

Abstract

The nature of the collagen in embryonic and postnatal bovine epiphyseal cartilage was studied by amino acid analysis, extraction in denaturants, and extraction in denaturants after prior digestion of the cartilage with pepsin. Components of both Type I collagen and Type II collagen were isolated by molecular sieve filtration from the gelatin extracted from 4–5 month old embryonic bovine epiphyseal cartilage, and characterized by their behavior during ion exchange chromatography, amino acid composition and their content of hydroxylysine and glycosydically substituted hydroxylysine residues. Type I collagen accounted for about one-third of the total collagen content of epiphyseal cartilage. It was preferentially extracted in denaturant salts, whilst Type II collagen, essentially insoluble in denaturants, could be extracted from the cartilage only after prior digestion of the cartilage with pepsin. The marked preponderance of α components compared with higher molecular weight polymers in the extracted Type I gelatin suggested a paucity of intramolecular crosslinkages, and the lability of the intermolecular crosslinks to denaturants at neutral pH, suggests that the intermolecular, aldehyde-derived crosslinks of Type, I collagen in cartilage are similar to those in the Type I collagen of bone rather than those present in the Type I collagen of skin and other non-mineralized connective tissues. The marked differences in the solubility properties of Type I and Type II collagens of cartilage suggests that the stability and possibly the chemical nature of the intermolecular crosslinkages in Type II collagen, as well as the number of intramolecular crosslinkages, differs in the two types of collagen present in cartilage.