Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8292090 | Archives of Biochemistry and Biophysics | 2007 | 12 Pages |
Abstract
Human peroxiredoxin 5 (PRDX5) catalyzes different peroxides reduction by enzymatic substitution mechanisms. Enzyme oxidation caused an increase in Trp84 fluorescence, allowing performing pre-steady state kinetic measurements. The technique was validated by comparing with data available from the literature or obtained herein by alternative approaches. PRDX5 reacted with organic hydroperoxides with rate constants in the 106-107Â Mâ1Â sâ1 range, similar to peroxynitrite-mediated PRDX5 oxidation, whereas its reaction with hydrogen peroxide was slower (105Â Mâ1Â sâ1). The method allowed determining the kinetics of intramolecular disulfide formation as well as thioredoxin 2-mediated reduction. The reactivities of PRDXs with peroxides were surprisingly high considering thiol pKa, indicating that other protein determinants are involved in PRDXs specialization. The order of reactivities between PRDX5 towards oxidizing substrates differ from other PRDXs studied, pointing to a selective action of PRDXs with respect to peroxide detoxification, helping to rationalize the multiple enzyme isoforms present even in the same cellular compartment.
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Authors
Madia Trujillo, André Clippe, Bruno Manta, Gerardo Ferrer-Sueta, Aude Smeets, Jean-Paul Declercq, Bernard Knoops, Rafael Radi,