Properties of a collagenase inhibitor partially purified from cultures of smooth muscle cells

An inhibitor of mammalian collagenase has been partially purified from the spent medium of smooth muscle cells grown in culture. The inhibitor is a glycoprotein with an apparent molecular weight of 25 000. It is stable to heat, acid, and mercurials, but it destroyed by trypsin treatment and by reductive alkylation. The inhibitor interacts with active mammalian collagenase and this interaction results in the loss of enzymatic activity. This presumptive collagenase-inhibitor complex is stable to the treatment with mercurials and to trypsin. These latter observations suggest that this inhibitor is different from other collagenase inhibitors that are thought to be responsible for the latency of the enzyme.