Neutral proteases of human granulocytes. IV. Interaction between human granulocyte collagenase and plasma protease inhibitors.

Purified human granulocyte collagenase was inactivated by serum through the formation of complexes with alpha 1-antitrypsin and alpha 2-macroglobulin. A molar combining ratio of 1:1 was observed for each inhibitor. The affinity of alpha 2-macroglobulin was about 10 times that of alpha 1-antitrypsin for granulocyte collagenase. The molar concentration of alpha 1-antitrypsin in the blood exceeds that of alpha 2-macroglobulin by about 12 times, so that the inhibitors may be equally important for defence against granulocyte collagenase.