| Type: | Domain | Name: | Peptidase M11, gametolysin |
| Description: | Metalloproteases are the most diverse of the four main types of protease, with more than 50 families identified to date. In these enzymes, a divalent cation, usually zinc, activates the water molecule. The metal ion is held in place by amino acid ligands, usually three in number. The known metal ligands are His, Glu, Asp or Lys and at least one other residue is required for catalysis, which may play an electrophillic role. Of the known metalloproteases, around half 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 [].This group of metallopeptidases belong to the MEROPS peptidase family M11 (gametolysin family, clan MA(M)). The protein fold of the peptidase domain for members of this family resembles that of thermolysin, the type example for clan MA and the predicted active site residues for members of this family and thermolysin occur in the motif HEXXH [].The type example is gametolysin from the unicellular biflagellated alga, Chlamydomonas reinhardtiiGametolysin is a zinc-containing metallo-protease, which is responsible for the degradation of the cell wall. Homologues of gametolysin have also been reported in the simple multicellular organism, Volvox [, ]. | Short Name: | Peptidase_M11 |
