Metalloproteinase

Metalloproteinases (or metalloproteases) constitute a family of enzymes from the group of proteases, classified by the nature of the most prominent functional group in their active site. These are proteolytic enzymes whose catalytic mechanism involves a metal. Most metalloproteases are zinc-dependent, but some use cobalt. The metal ion is coordinated to the protein via three ligands. The ligands co-ordinating the metal ion can vary with histidine, glutamate, aspartate, lysine and arginine. The fourth coordination position is taken up by a labile water molecule.

There are two subgroups of metalloproteinases:
 * exopeptidases: metalloexopeptidases (EC number: 3.4.17).
 * endopeptidases: metalloendopeptidases (3.4.24). Well known metalloendopeptidases include ADAM proteins and matrix metalloproteinases.

Treatment with chelating agents such as EDTA leads to complete inactivation. EDTA is a metal chelator which removes zinc, which is essential for activity. They are also inhibited by the chelator orthophenanthroline.