AN INVESTIGATION OF PRODUCTS OF AN ENZYMIC HYDROLYSIS OF COLLAGENS

Ichthyocol and insoluble, acid-soluble, and saltsoluble bovine collagen were digested enzymically with collagenase, papain, and a mixture of prolidase and leucine aminopeptidase. Analysis of the protein-free product showed that 70-80 % of the residues was present as free amino acids. The peptides present were isolated and their quantity and sequences were determined. Most of the peptides were tripeptides with the general sequence of Gly-Pro-X and X-Hyp-Gly as would be expected from the known specificities of the enzymes and the available sequence information concerning the collagen chains. The peptide, Gly-Pro-Hyp, was present to the extent of 40 and 32 moles per chain in the digests of bovine and ichthyocol collagen, respectively. Several peptides were found which have not been previously reported. A peptide having the tentatively determined sequence of Gly-(Gln, Hyp, ε-Lys) was also located. The quantity of each amino acid occurring in the peptides together with the quantity of each free amino acid accounted for essentially all of the residues when compared with acid hydrolysates of the enzymic hydrolysates. Except for two to three residues of glutamine in peptide sequences, all residues of glutamic acid and glutamine were liberated by the enzymes. Judging from the specificities of the pure enzymes, this should not occur if collagen contains γ-glutamyl linkages. © 1969, American Chemical Society. All rights reserved.