Direct measurement of neutral collagenase activity in homogenates from baboon and human liver

Neutral collagenase (EC 3.4.24.7) has been detected in human liver biopsies, baboon liver for the first time. The reaction mixtures were composed of collagen in solution and total liver homogenate in 0.5 M Tris-HCl, pH 7.5 at 25 degree C/0.2 M NaCl/10 mM CaCl2/3 mM p-chloromercuribenzoic acid. Collagenase activity was found by directly subjecting the reaction mixtures to viscometric assay and the activity was confirmed to be due to neutral collagenase by identifying the products using disc gel electrophoresis. It proved necessary to use p-chloromercuribenzoic acid in order to reveal collagenase activity in total liver homogenates from these species. The p-chloromercuribenzoic acid served to inhibit thiol proteinases and all other signs of nonspecific collagenolysis on disc gel electrophoresis, and it was able to activate latent collagenase which trypsin could not.