Purification, characterization and inhibition of human skin collagenase

Abstract

The neutral collagenase released into the culture medium by explants of human skin tissue was purified by ultrafiltration and column chromatography. The final enzyme preparation had a specific activity against thermally reconstituted collagen fibrils of 32 .mu.g of collagen degraded/min per mg of enzyme protein, representing a 266-fold increase over that of the culture medium. Electrophoresis in polyacrylamide disc gels showed it to migrate as a single protein band from which enzyme activity could be eluted. Chromatographic and polyacrylamide-gel-elution experiments provided no evidence for the existence of more than 1 active collagenase. The MW of the enzyme estimated from gel filtration and sodium dodecyl sulfate/polyacrylamide-gel electrophoresis was .apprx. 60,000. The purified collagenase, having a pH optimum of 7.5-8.5, did not hydrolyze the synthetic collagen peptide 4-phenylazobenzyloxycarbonyl-Pro-Leu-Gly-Pro-D-Arg-OH and had no non-specific proteinase activity when examined against non-collagenous proteins. It attacked undenatured collagen in solution at 25.degree. C, producing the 2 characteristic products TCA (3/4) and TCB (1/4). Collagen types I, II and III were all cleaved in a similar manner by the enzyme at 25.degree. C, but under similar conditions base- ment-membrane collagen appeared not to be susceptible to collagenase attack. At 37.degree. C the enzyme attacked gelatin, producing initially 3/4 and 1/4 fragments of the .alpha.-chains, which were degraded further at a lower rate. As judged by the release of soluble hydroxyproline peptides and EM, the purified enzyme degraded insoluble collagen derived from human skin at 37.degree. C, but at a rate much lower than that for reconstituted collagen fibrils. Inhibition of the skin collagenase was obtained with EDTA, 1,10-phenanthroline, cysteine, dithiothreitol and sodium aurothiomaleate. Cartilage proteoglycans did not inhibit the enzyme. The serum proteins .alpha.2-macroglobulin and .beta.1-anti-collagenase both inhibited the enzyme, but .alpha.1-anti-trypsin did not. The physicochemical and enzymic properties of the skin enzyme are discussed in relation to those of other human collagenases.