Kinetic study of the reaction of glutathione peroxidase with peroxynitrite.
Glutathione peroxidases and their mimics, e.g., ebselen or diaryl tellurides, efficiently reduce peroxynitrite/peroxynitrous acid (ONOO-/ONOOH) to nitrite and protect against oxidation and nitration reactions. Here, we report the second-order rate constant for the reaction of the reduced form of glutathione peroxidase (GPx) with peroxynitrite as (8.0 +/- 0.8) x 10(6) M-1 s-1 (per GPx tetramer) at pH 7.4 and 25 degreesC. The rate constant for oxidized GPx is about 10 times lower, (0.7 +/- 0.2) x 10(6) M-1 s-1. On a selenium basis, the rate constant for reduced GPx is similar to that obtained previously for ebselen. The data support the conclusion that GPx can exhibit a biological function by acting as a peroxynitrite reductase.
Briviba
K
K
Institut für Physiologische Chemie I, Heinrich-Heine-Universität D usseldorf, Postfach 101007, D-40001 Düsseldorf, Germany.
Kissner
R
R
Koppenol
W H
WH
Sies
H
H
D005979:Glutathione Peroxidase / Q000737:chemistry*; D007202:Indicators and Reagents; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry*; D010084:Oxidation-Reduction
D007202:Indicators and Reagents; D009566:Nitrates; C039642:peroxynitric acid; D005979:Glutathione Peroxidase