Conformational criteria for the enzymatic hydroxylation of proline in collagen

Abstract

With a view to understanding the conformational specificity of peptidyl proline hydroxylase, we have generated the secondary structure of the unhydroxylated collagen chain based on the available amino acid sequence data, using the procedure of Chou and Fasman. It is found that the probability of occurrence of a given chain segment, -Z-Pro-Gly-X- (where Z and X are amino acid residues) in the β-turn conformation, has a good correlation with the degree of hydroxylation of the proline residue in the segment by the enzyme. The enzyme, therefore, seems to recognize the β-turn as the conformational feature in the substrate. The hydroxylation of the proline residue results in the straightening of the β-turn regions giving rise to a rigid chain, The available data on the hydroxylation of natural and synthetic substrates by the enzyme, are explained in a unified fashion by our hypothesis.