Peptidase M1, aminopeptidase (IPR012778)

Short name: Pept_M1_aminopeptidase

Overlapping homologous superfamilies


Family relationships



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 play an electrophillic role. Many metalloproteases 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 family is a subset of the members of the zinc metallopeptidases belonging to MEROPS peptidase family M1 (aminopeptidase N, clan MA), with a single member characterised in Streptomyces lividans: aminopeptidase G [PMID: 7765336]. The rest of the members of this family are identified as aminopeptidase N of the actinomycete-type. The spectrum of activity may differ somewhat from the aminopeptidase N clade of Escherichia coli and most other proteobacteria, which are well separated phylogenetically within the M1 family.

GO terms

Biological Process

GO:0006508 proteolysis

Molecular Function

GO:0004177 aminopeptidase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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