Metzincin family activation

The MMP enzyme family is part of the superfamily of metzincins. The metzincin superfamily is distinguished by a conserved zinc binding motif for the catalytic zinc and a Met-turn region [4]. The MMPs are unique in that they also contain a second structural zinc, however this zinc may be absent in the intact full-length enzyme [5]. The presence of one to four structural calcium ions has been detected in the MMPs that have been characterized to date. The importance of the zinc ions and at least one of the structural calcium ions to enzymatic activity has been proven [6]. 

Fig. 2. Structure and active site of clostridial neurotoxins. The upper panel shows the structure of CNTs, and the segments that show significant homology between the different serotypes are in black (Minton, 1995). The highest homology is shown by a short segment corresponding to the amino acid residues 216-244 in TeTx. This segment contains the zinc-binding motif of metallo-proteinases (zincins) and it is dissimilar to the consensus sequence of the metzincin metallo-proteinase family (Jiang and Bond, 1992)...

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