Family M42


Summary Holotypes Alignment Tree Genomes Structure Literature

Summary for family M42

NamePeptidase family M42 (glutamyl aminopeptidase family)
Family type peptidaseM42.001 - glutamyl aminopeptidase (bacterium) (Lactococcus lactis), MEROPS Accession MER0002040 (peptidase unit: 1-355)
Content of familyPeptidase family M42 contains metalloaminopeptidases some of which also have acylaminoacylpeptidase activity.
History Identifier created: Handbook of Proteolytic Enzyme, Academic Press, London (1998)
Relevant recent reviews are those of Motoshima & Kaminogawa, 2004, Niven, 2004 and Tsunasawa, 2004.
Catalytic typeMetallo
Active site residuesH65 D67 D181 E213 E214 E,D236 H319 
Active siteThese peptidases are co-catalytic metallopeptidases, typically binding two atoms of zinc or cobalt. See above for the locations of the catalytic residues and metal ligands.
Activities and specificitiesSome of the enzymes exhibit typical aminopeptidase specificity, whereas others are also able to hydrolyse acylated N-terminal residues, the so-called 'N-terminal deblocking activity'. Characteristics commonly reported are exceptional thermal stability and a requirement for cobalt ions for maximal activity (Roncari et al., 1972; Ando et al., 1999; Onoe et al., 2002).
Molecular structureIndications of the three-dimensional molecular structure were obtained for M42.005 from Haloarcula marismortui by electron microscopy (Franzetti et al., 2002), and crystal structures have been solved for an unclassified member of the family from Bacillus subtilis (M42.UPW; PDB/1VHE) and for the aminopeptidase from Pyrococcus horikoshii (M42.003; Russo & Baumann 2004). The aminopeptidases exist as complexes of twelve identical subunits in which all the active sites are located in the interior of the molecule, and access of substrates is restricted by 10-Angstrom pores.
Basis of clan assignmentFor members of this family and family M28 predicted metal ligands occur in the same order in the sequence: H, D, E, D/E, H; and active site residues in the motifs HXD and EE
Distribution of family Bacteria details  
Archaea details  
Protozoa details  
Fungi details  
Plants -  
Animals details  
Viruses details  
Biological functionsGlutamyl aminopeptidase PepA (Lactococcus lactis) (M42.001) aids growth of the organism in milk (I"Anson et al., 1995).
Pharmaceutical and biotech relevanceThe deblocking aminopeptidase of Pyrococcus horikoshii (M42.003) is capable of hydrolysing N-terminal acylated amino acids as well as free N-terminal residues, which can be valuable in N-terminal protein sequencing (Tsunasawa, 1998).
Statistics for family M42Sequences:4126
Identifiers with PDB entries:8
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
glutamyl aminopeptidase (bacterium)M42.001Yes
aminopeptidase I (Bacillus-type)M42.002-
PhTET1 aminopeptidaseM42.003Yes
PhTET2 aminopeptidaseM42.004Yes
TET aminopeptidaseM42.005-
FrvX putative peptidaseM42.006Yes
TM1048-type putative peptidaseM42.007Yes
YpdE-type putative peptidaseM42.008Yes
PhTET3 aminopeptidaseM42.009Yes
CelM peptidaseM42.010-
SgcX protein (Escherichia coli)M42.A01-
yhfE g.p. (Bacillus subtilis)M42.A02-
family M42 non-peptidase homologuesnon-peptidase homologue-
family M42 unassigned peptidasesunassignedYes