[Isolation and characterization of a metalloprotease associated with chicken epiphyseal cartilage matrix vesicles].

Matrix vesicles are present in the calcifying front and in the site of callus formation of fracture heeling. In calcifying process, matrix vesicles have important roles. The metalloprotease was isolated from matrix vesicles and subsequently characterized. Matrix vesicles obtained from chicken epiphysial cartilage by collagenase digestion and differential centrifugation were further purified by Sepharose CL2B gel filtration. The protease was solubilized from the vesicles and isolated by Sephadex G-150 gel filtration. Disc electrophoresis of the enzyme gave a single protein band. The matrix vesicle protease had a MW of 33,000 daltons, an optimal pH of 7.2, and was inhibited 100% by 0.1 mM EDTA and 0.2 mM o-Phenanthroline. alpha 2-Macroglobulin, ovalbumin, cysteine, penicillamine, ethane-1-hydroxy-1, 1-diphosphonate (EHDP) and pyrophosphate at higher concentrations were also inhibitory. The inhibition by o-phenanthroline was reversed by Co2+, Zn2+, Fe2+ and Cu2+. The protease released from the matrix vesicle at the calcifying front could degrade non-collagenous protein moieties which inhibit precipitation of minerals in the extra-vesicular matrix and thus facilitate mineralization.