“…Dipeptidyl aminopeptidase (DAP or DPP; EC 3.4.14) catalyses the removal of dipeptides from the amino-termini of peptides and proteins. In microorganisms, we have reported the identification, purification and characterization of DAP BI (bacterial dipeptidyl aminopeptidase; Ogasawara, Ochiai et al, 1996;Ogasawara et al, 1998); DAP BII (Ogasawara, Kobayashi et al, 1996;Suzuki et al, 2014;Sakamoto et al, 2014); DAP BIII (Ogasawara, Kobayashi et al, 1996); DAP IV (in this paper, we designate bacterial DPP IV as DAP IV; Ogasawara, Ogawa et al, 1996;Ogasawara et al, 2005) and prolyloligopeptidase (POP; Ogasawara et al, unpublished work) from Pseudoxanthomonas mexicana WO24, which is a Gram-negative aerobic bacteria isolated from the wastewater of a bean-curd (tofu) factory. We have demonstrated that DAP BI, DAP BIII, DAP IV and POP belong to the POP family (Kanatani et al, 1991;Rawlings et al, 1991) and that they are classified into clan SC, family S9 in the MEROPS database (Rawlings et al, 2014), whereas DAP BII is classified into the clan PA, family S46 (Suzuki et al, 2014;Sakamoto et al, 2014).…”