A human cartilage metalloproteinase with elastolytic activity

A metalloproteinase with elastolytic properties found in human fetal and osteoarthritic cartilage could not be detected in normal adult cartilage. During extraction the enzyme appeared to be mostly associated with cartilage proteoglycans, from which it can be separated by ion exchange chromatography. This enzyme migrated during electrophoresis with an apparent molecular weight of 62,000 daltons and was found to be fully activated in the tissue under the study conditions. The enzyme showed a preference for substrates rich in non-polar amino acid residues and was capable of breaking down elastin and casein at neutral pH. The enzyme activity can be inhibited by chelating agents and specific affinity reagents, chloroketones, and is not inhibited by other proteinase inhibitors such as PMSF, aprotinin and alpha-1-antitrypsin. This enzyme may play a significant role in conditions demanding rapid cartilage matrix turnover and/or remodeling, such as normal embryonic development or osteoarthritis.