| Primary Identifier | IPR001333 | Type | Family |
| Short Name | Peptidase_M32_Taq |
| description | This group of metallopeptidases belong to MEROPS peptidase family M32 (carboxypeptidase Taq family, clan MA(E)). The predicted active site residues for members of this family and thermolysin, the type example for clan MA, occur in the motif HEXXH. Carboxypeptidase Taq (TaqCP) is a zinc-containing thermostable metallopeptidase [, ]. It was originally discovered and purified from Thermus aquaticus; optimal enzymatic activity occurs at 80 Celsius []. This family also includes Pyrococcus furiosus thermostable carboxypeptidase (PfuCP) []and carboxypeptidase 1 from Bacillus subtilis []. Over 70 metallopeptidase families have been identified to date. In these enzymes a divalent cation which is usually zinc, but may be cobalt, manganese or copper, activates the water molecule. The metal ion is held in place by amino acid ligands, usually three in number. In some families of co-catalytic metallopeptidases, two metal ions are observed in crystal structures ligated by five amino acids, with one amino acid ligating both metal ions. The known metal ligands are His, Glu, Asp or Lys. At least one other residue is required for catalysis, which may playan electrophillic role. Many metalloproteases contain an HEXXH motif, which has been shown in crystallographic studies to form part of the metal-binding site []. The HEXXH motif is relatively common, but can be more stringently defined for metalloproteases as 'abXHEbbHbc', where 'a' is most often valine or threonine and forms part of the S1' subsite in thermolysin and neprilysin, 'b' is an uncharged residue, and 'c' a hydrophobic residue. Proline is never found in this site, possibly because it would break the helical structure adopted by this motif in metalloproteases []. |
