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Dipeptidyl peptidase I and III activities of adult schistosomes

Published online by Cambridge University Press:  01 March 1999

L. HOLA-JAMRISKA
Affiliation:
Molecular Parasitology Unit, and Australian Centre for International and Tropical Health and Nutrition, Queensland Institute of Medical Research, Post Office, Royal Brisbane Hospital, Queensland 4029, Australia School of Life Science, Queensland University of Technology, Gardens Point, Queensland 4001, Australia
J. P. DALTON
Affiliation:
Molecular Parasitology Unit, and Australian Centre for International and Tropical Health and Nutrition, Queensland Institute of Medical Research, Post Office, Royal Brisbane Hospital, Queensland 4029, Australia School of Biological Sciences, Dublin City University, Dublin 9, Republic of Ireland
J. AASKOV
Affiliation:
School of Life Science, Queensland University of Technology, Gardens Point, Queensland 4001, Australia
P. J. BRINDLEY
Affiliation:
Molecular Parasitology Unit, and Australian Centre for International and Tropical Health and Nutrition, Queensland Institute of Medical Research, Post Office, Royal Brisbane Hospital, Queensland 4029, Australia

Abstract

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.

Type
Research Article
Copyright
1999 Cambridge University Press

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