Hydroxyproline and thermal stability of collagen.

Abstract

GUSTAVSON1 has recently directed attention to the importance of hydroxyproline residues in determining the hydrothermal stability of a collagen. He examined collagen samples from two broad sources, namely, mammalian and teleost connective tissue, and his findings demonstrated a direct relationship between the hydroxyproline content of a collagen and its shrinkage temperature. He considers that hydroxyproline will form interchain hydrogen bonds between its hydroxyl group and the carbonyl oxygen of an adjacent peptide grouping and may also be involved in the formation of ester links between polypeptide chains, thus playing a very important part in determining the stability and general reactivity of a collagen fibre. The evidence for assigning such a function to the hydroxyproline residue has, however, been derived from a study of many animal species. Furthermore, there is a growing body of evidence2–4 which indicates that the reactivity of a collagen fibre depends on age and it still remains to be established whether variations in the hydroxyproline content can account for the differing degrees of reactivity with age, shown by collagen obtained from a single animal species.