Inhibition of human collagenase activity by a small molecular weight serum protein

Fractionation of human serum proteins by gel filtration in Sephadex G-200 revealed two regions of collagenase inhibition which corresponded to α2-macroglobulin and a smaller serum component which eluted after α1-antitrypsin. The smaller collagenase inhibitor, having a molecular weight of 40,000 was separated from α1-antitrypsin by chromatography in Sephadex DEAE A.50. It was found to inhibit human collagenases derived from skin, rheumatoid synovium, gastric mucosa and granulocytes, but not the neutral proteases trypsin and papain. Purified preparations of α1-antitrypsin inhibiting trypsin and papain had no effect on the collagenase activities. The small collagenase inhibitor may have importance as a regulatory factor in the control of collagenase activity in vivo.