Studies on the role of proteases in the biochemical mechanisms of tissue injury.

A complex of inflammatory protease with an inhibitor was found to be present in the early phase of Arthus skin lesions in guinea pig. From the extract of inflamed lesions a complex was partially purified by chromatography on DEAE-Sephadex A-50 and GE-cellulose, in that order. The inhibitor was finally dissociated rom the protease complex by treating them with cysteine followed by Sephadex G-50 chromatography. Active protease was recovered as a single peak which also contained some inhibitor activity. The isolated inhibitor was capable of inactivating inflammatory protease as well as papain. It was electrophoretically homogenous and was identified as protein or polypeptide in the serum alpha-1-globulin fraction. The significant role of the inhibitor in regulating the acute phase of inflammatory process is emphasized.