Dipeptidyl peptidase I and III activities of adult schistosomes.
Soluble extracts of adult Schistosoma japonicum and S. mansoni were examined for the presence of proteolytic activities ascribable to dipeptidyl peptidases (DPPs) at a range of pH from 4 to 11 using synthetic peptidyl substrates diagnostic of DPPs I, II, III and IV. Activity capable of cleaving the DPP I-specific substrates H-Gly-Arg-NHMec and H-Gly-Phe-NHMec which exhibited a pH optimum of 5.5 was observed in extracts of schistosomes. Female schistosomes exhibited greater DPP I activity than male schistosomes, while female S. japonicum showed substantially more activity than female S. mansoni. The specific activities against H-Gly-Arg-NHMec were 21.5 and 1.9 nmoles NHMec/min/mg protein for female and male S. japonicum and 8.5 and 1.9 nmoles NHMec/min/mg for female and male S. mansoni. The biochemical properties of schistosome DPP I were similar to mammalian DPP I (= cathepsin C) in that schistosome DPP I was only slowly inhibited by the cysteine protease inhibitor trans-epoxysuccinyl-1-leucylamido (4-guanidino)-butane, partly inhibited by the blocked diazomethyl ketones Z-Phe-Ala-CHN2 and Z-Phe-Phe-CHN2, but enhanced by halide ions. At pH 8.5, activity against the DPP III-specific substrate H-Arg-Arg-NHMec was evident in schistosome extracts, and this activity appeared to be due to a zinc metallo-exopeptidase because it was inhibited by 1,10-phenathroline and by EDTA. DPP II or DPP IV activity was not detected in the schistosome extracts.
Hola-Jamriska
L
L
Molecular Parasitology Unit, Royal Brisbane Hospital, Queensland, Australia.
Dalton
J P
JP
Aaskov
J
J
Brindley
P J
PJ
D000818:Animals; D020789:Cathepsin C; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D008297:Male; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism; D012549:Schistosoma japonicum / Q000201:enzymology*; D012550:Schistosoma mansoni / Q000201:enzymology*
D010455:Peptides; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D020789:Cathepsin C; C100152:dipeptidyl peptidase III