Characterization of the metalloproteinase inhibitor produced by bovine articular chondrocyte cultures

Primary cultures of bovine articular chondrocytes release a latent metalloproteinase which is activated by incubation with organomercurials to degrade proteoglycans. All the enzyme present in the culture medium is latent and binds to columns of heparin-Sepharose. The yield of activity from the heparin-Sepharose columns (measured after organomercurial treatment) is approximately 300–1000% depending on the chondrocyte culture batch. Recombination of column fractions shows that the increase in activity is due to the separation of an inhibitor of the metalloproteinase by the chromatographic step. The metalloproteinase inhibitor has a molecular weight of approximately 35 000 (determined by Bio-Gel P-60 chromatography) and binds reversibly to columns of concavalin A-Sepharose. It is relatively heat stable (30 min at 60°C) and resistant to inactivation by trypsin (2 h, 37°C, 10 μg/ml trypsin). The inhibitor is active against rat uterine collagenase and gelatinase but does not affect bacterial metalloproteinases such as thermolysin and Clostridium histolyticum collagenase.