Conserved Site

Peptidase M24B, X-Pro dipeptidase/aminopeptidase P, conserved site (IPR001131)

Short name: Peptidase_M24B_aminopep-P_CS


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 [PMID: 7674922]. 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 [PMID: 7674922].

This entry represents the cataltyic core of a group of metallopeptidases belong to MEROPS peptidase family M24 (clan MG), subfamily M24B.

A number of different enzymes from various sources have the proline dipeptidase domain. Enzymes know to have this domain include the Xaa-Pro dipeptidase (EC: (prolidase) and the Xaa-Pro aminopeptidase (EC:

Xaa-Pro dipeptidase (EC: (prolidase) splits dipeptides with a prolyl residue in the carboxyl terminal position. Xaa-Pro aminopeptidase (EC: is the enzyme responsible for the release of any N-terminal amino acid adjacent to a proline residue.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns