Short Spacer or Metzincins Family

Proteins which have the consensus HexxHxxgxxH, where the separation between the first and third (histidine) zinc ligands is nine residues. When the primary sequence in regions other than the zinc binding motif are considered, these proteases to be grouped into four [4, 5,33] classes (Fig. 2). Since most of the zinc proteases are multimodular proteins, with indi- 

The overall structure of these metalloproteins is characterized by a deep active site cleft that divides the molecule into two domains, with the catalytically active zinc located at the bottom of the active site in the center of the molecule (Fig. 3). The structures of protein-inhibitor complexes [15,17,19-26] representing different families, indicate that the PI residue [37] is the principal recognition element for these enzymes (Fig. 5). Inhibitors bound to members of the matrixin family [17,19-23,25] adopt an extended conformation (Fig. 6), with the side chain at the P2 subsite directed away from the enz5mie on the opposite side of the inhibitor backbone to the PI specificity pocket. In addition to the zinc ligands, there are essential enzyme-inhibitor interactions between backbone atoms of the protein and complementary atoms of the inhibitor 1. 

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