Biochemical characterisation of the recombinant peroxiredoxin (FhePrx) of the liver fluke, Fasciola hepatica

The parasitic helminth Fasciola hepatica secretes a 2-Cys peroxiredoxin (Prx) that may play important functions in host-parasite interaction. Recombinant peroxiredoxin (FhePrx) prevented metal-catalyzed oxidative nicking of plasmid DNA and detoxilied hydrogen peroxide when coupled with Escherichia coli thioredoxin and thioredoxin reductase (k(cat)/K-m = 5.2 x 10(5) M-1 s(-1)). Enzyme kinetic analysis revealed that the catalytic efficiency of FhePrx is similar to other 2-Cys peroxiredoxins; the enzyme displayed saturable enzyme Michaelis-Menten type kinetics with hydrogen peroxide, cumene hydroperoxide and t-butyl hydroperoxide, and is sensitive to concentrations of hydrogen peroxide above 0.5 mM. Like the 2-Cys peroxiredoxins from a related helminth, Schistosoma mansoni, steady-state kinetics indicate that FhePrx exhibits a saturable, single displacement-like reaction mechanism rather than non-saturable double displacement (ping-pong) enzyme substitution mechanism common to other peroxiredoxins. However, unlike the schistosome Prxs, FhePrx could not utilise reducing equivalents supplied by glutathione or glutathione reductase. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.