title: Redox potential and peroxide reactivity of human peroxiredoxin 3.
abstract: Peroxiredoxins (Prxs) are a ubiquitous family of thiol peroxidases that protect cells from peroxides and have a putative role in redox signaling. In this study, we investigated the redox properties of human Prx 3, a typical 2-Cys Prx that is localized to the mitochondrial matrix. We found that Prx 3 displayed strong reactivity with H(2)O(2), with a competitive kinetic approach generating a second order rate constant of 2 x 10(7) M(-1) s(-1). This is considerably higher than typical thiols and similar to values for other mammalian 2-Cys Prxs. In contrast, Prx 3 reacted very slowly with the thiol alkylating agents iodoacetamide and N-ethylmaleimide. Using dithiothreitol redox buffers, we measured the redox potential of Prx 3 of -290 mV. This is similar to the redox potential of mitochondrial thioredoxin 2 and is consistent with optimal operation of Prx 3 in the mitochondrial matrix.
authors.affiliation: Free Radical Research Group and National Research Centre for Growth and Development, Department of Pathology, University of Otago, Christchurch, New Zealand.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Cox
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Peskin
authors.forename: Louise N
authors.initials: LN
authors.lastname: Paton
authors.forename: Christine C
authors.initials: CC
authors.lastname: Winterbourn
authors.forename: Mark B
authors.initials: MB
authors.lastname: Hampton
mesh_terms: D000478:Alkylation; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007700:Kinetics; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry*; D061105:Peroxiredoxin III; D054464:Peroxiredoxins / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D010545:Peroxides; D013438:Sulfhydryl Compounds; C516115:PRDX3 protein, human; D061105:Peroxiredoxin III; D054464:Peroxiredoxins