Cleaves the N-terminal amino acid of tripeptides. Release of the N-terminal residue from a tripeptide. Binds 2 Zn(2+) ions per subunit. To a lesser extent, can also use Co(2+) or Mn(2+) instead of Zn(2+). Activity is strongly inhibited in vitro by chelating agents such as EDTA and 1,10-phenanthroline as do the reducing agent dithiothreitol and the oxidizing agent N-bromosuccinimid. Phenylmethylsulfonyl fluoride, a serine protease inhibitor has no influence on the enzyme activity. On the other hand, bestatin, an aminopeptidase inhibitor strongly inhibits the enzyme activity and leupeptin, a modified tripeptide, slightly inhibits it. kcat is 163 sec(-1) with AAA tripeptide as substrate. kcat is 616 sec(-1) with GAA tripeptide as substrate. kcat is 713 sec(-1) with AGA tripeptide as substrate. kcat is 730 sec(-1) with AAG tripeptide as substrate. kcat is 507 sec(-1) with GGA tripeptide as substrate. kcat is 573 sec(-1) with AGG tripeptide as substrate. kcat is 1093 sec(-1) with GAG tripeptide as substrate. kcat is 502 sec(-1) with GGG tripeptide as substrate. kcat is 292 sec(-1) with YGG tripeptide as substrate. kcat is 197 sec(-1) with LGG tripeptide as substrate. kcat is 262 sec(-1) with FGG tripeptide as substrate. kcat is 270 sec(-1) with SGG tripeptide as substrate. kcat is 31.2 sec(-1) with AibGG tripeptide as substrate. kcat is 453 sec(-1) with GGF tripeptide as substrate. kcat is 806 sec(-1) with GAY tripeptide as substrate. Optimum pH is around 8. The enzyme is stable in a pH range of 9-10. Optimum temperature is around 44 degrees Celsius. The enzyme is stable up to 50 degrees Celsius. Homodimer. Belongs to the peptidase M20B family.