title: Identification and partial purification of a dipeptidyl aminopeptidase from Streptococcus faecalis.
abstract: A dipeptidyl aminopeptidase was identified in Streptococcus faecalis JH2SS and was partially purified (approximately 245-fold) by HPLC. Gel filtration chromatography indicated an Mr of 140 000. The partially purified enzyme exhibited a requirement for Co2+. The pH optimum for the hydrolysis of L-Val-L-Ala-p-nitroanilide was approximately 9.5. The apparent Km for this substrate was 0.22 mM. The enzyme preferentially hydrolysed X-Ala-Y substrates, but also utilized X-Pro-Y substrates, and therefore is most closely related to the mammalian dipeptidyl aminopeptidase II (EC 3.4.14.-). The enzyme was inhibited by p-chloromercuribenzoate, but not by iodoacetate, N-ethylmaleimide or the serine protease inhibitor phenylmethylsulphonyl fluoride.
mesh_terms: D002413:Cations, Divalent; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D013293:Enterococcus faecalis / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D013379:Substrate Specificity
chemical_list: D002413:Cations, Divalent; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases