期刊
FREE RADICAL BIOLOGY AND MEDICINE
卷 50, 期 9, 页码 1032-1038出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.freeradbiomed.2011.02.020
关键词
Reactive cysteines; Hydrogen peroxide; Hydrogen peroxide sensors; Horseradish peroxidase; Peroxiredoxin kinetics; rPrdx6 kinetics; Free radicals
资金
- Fundacao de Amparo A Pesquisa do Estado de Sao Paulo (FAPESP)
- Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)
- Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)
Proteins containing reactive cysteine residues (protein-Cys) are receiving increased attention as mediators of hydrogen peroxide signaling. These proteins are mainly identified by mining the thiol proteomes of oxidized protein-Cys in cells and tissues. However, it is difficult to determine if oxidation occurs through a direct reaction with hydrogen peroxide or by thiol-disulfide exchange reactions. Kinetic studies with purified proteins provide invaluable information about the reactivity of protein-Cys residues with hydrogen peroxide. Previously, we showed that the characteristic UV-Vis spectrum of horseradish peroxidase compound I, produced from the oxidation of horseradish peroxidase by hydrogen peroxide, is a simple, reliable, and useful tool to determine the second-order rate constant of the reaction of reactive protein-Cys with hydrogen peroxide and peroxynitrite. Here, the method is fully described and extended to quantify reactive protein-Cys residues and micromolar concentrations of hydrogen peroxide. Members of the peroxiredoxin family were selected for the demonstration and validation of this methodology. In particular, we determined the pK(a) of the peroxidatic thiol of rPrx6 (5.2) and the second-order rate constant of its reactions with hydrogen peroxide ((3.4 +/- 0.2) x 10(7) M(-1) s(-1)) and peroxynitrite ((3.7 +/- 0.4) x 10(5) M(-1) s(-1)) at pH 7.4 and 25 degrees C. (C) 2011 Elsevier Inc. All rights reserved.
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