Resolution of TIMP-free and TIMP-complexed 70kDa progelatinase from culture medium of Rous sarcoma virus-transformed...

Chicken embryo fibroblasts (CEF) produce a 70kDa progelatinase, a member of the matrix metalloproteinase family, and secrete elevated levels of the enzyme upon transformation by Rous sarcoma virus (RSV). This enzyme can be purified by affinity chromatography complexed with a 21kDa tissue inhibitor of metalloproteinases (TIMP)-like molecule. Gel-filtration of the purified progelatinase suggests the presence of a mixed population of enzyme: a TIMP-complexed and a TIMP-free progelatinase. These two species were separated by Mono Q FPLC in the absence of denaturants. Quantitation of the purified progelatinase reveals that the transformed RSVCEF produce more TIMP-free enzyme than the normal CEF. Native PAGE analysis indicates that purified TIMP-free progelatinase is capable of binding to TIMP and generating a TIMP-complexed progelatinase. Treatment of the TIMP-free gelatinase with organomercurials results in a rapid conversion to the active 62kDa species and indicates that the TIMP-free progelatinase is more susceptible to activation than the TIMP-complexed progelatinase.