Cytosolic metallopeptidase that catalyzes the removal of unsubstituted N-terminal hydrophobic amino acids from various peptides (PubMed:6108111, PubMed:12675513). The presence of Zn(2+) ions is essential for the peptidase activity, and the association with other cofactors can modulate the substrate spectificity of the enzyme (By similarity). For instance, in the presence of Mn(2+), it displays a specific Cys-Gly hydrolyzing activity of Cys-Gly-S-conjugates (By similarity). Involved in the metabolism of glutathione and in the degradation of glutathione S-conjugates, which may play a role in the control of the cell redox status (PubMed:12675513). Release of an N-terminal amino acid, Xaa-|-Yaa-, in which Xaa is preferably Leu, but may be other amino acids including Pro although not Arg or Lys, and Yaa may be Pro. Amino acid amides and methyl esters are also readily hydrolyzed, but rates on arylamides are exceedingly low. an S-substituted L-cysteinylglycine + H2O = an S-substituted L-cysteine + glycine H2O + L-cysteinylglycine = glycine + L-cysteine H2O + S-benzyl-L-cysteinylglycine = glycine + S-benzyl-L-cysteine Release of N-terminal proline from a peptide. Binds two metal ions per subunit. Two metal binding sites with different affinities are located in the enzyme active site and can be occupied in vitro by different metals: site 1 is occupied by Zn(2+), Mn(2+), Mg(2+) or Co(2+), while the tight binding site 2 can be occupied by only Zn(2+) or Co(2+). One Zn(2+) ion is tightly bound to site 2 and essential for enzyme activity in vivo, while site 1 can be occupied by different metals to give different enzymatic activities. Mn(2+) is required for Cys-Gly hydrolysis activity. A third metal binding site may serve a structural role, possibly stabilizing part of the interface between the N-terminal and the catalytic domain. Bimane-S-cysteinylglycine-hydrolyzing activity is inhibited by o-phenanthroline or bestatin, and is activated by the addition of zinc chloride. Homohexamer. Belongs to the peptidase M17 family.