Covalent structure of collagen: amino acid sequence of alpha 2-CB5 of chick skin collagen containing the animal collagenase cleavage site.

The amino acid sequence of the 112 residues from the amino terminus of alpha 2-CB5 from chick skin collagen was determined by automated sequential degradation of intact alpha 2-CB5 and several chymotryptic and tryptic peptides. This segment of the peptide includes the site of the action of animal collagenases. As compared to the sequence around the alpha 1 cleavage site, the alpha 2 sequence is notable for the remarkable constancy of the residues to the amino side and the relative abundance of hydrophobic residues to the carboxyl side of the cleavage site, suggesting that these features are important in the recognition by the enzyme. The sequence of this region of the alpha 2 chain is consistent with the Gly-X-Y triplet structure and the preference of certain residues for either the X or Y position in distribution. However, three of the six residues of leucine were found in the Y position rather than the X position. Leucine residues were found only once in the Y position in the alpha 1 (I) chain. This preference does not appear to hold in the alpha 2 chain.