Reaction
The main reaction that glutathione peroxidase catalyzes is:
- 2GSH + H2O2 → GS–SG + 2H2O
where GSH represents reduced monomeric glutathione, and GS–SG represents glutathione disulfide. The mechanism involves oxidation of the selenol of a selenocysteine residue by hydrogen peroxide. This process gives the derivative with a selenenic acid (RSeOH) group. The selenenic acid is then converted back to the selenol by a two step process that begins with reaction with GSH to form the GS-SeR and water. A second GSH molecule reduces the GS-SeR intermediate back to the selenol, releasing GS-SG as the by-product. A simplified representation is shown below:
- RSeH + H2O2 → RSeOH + H2O
- RSeOH + GSH → GS-SeR + H2O
- GS-SeR + GSH → GS-SG + RSeH
Glutathione reductase then reduces the oxidized glutathione to complete the cycle:
- GS–SG + NADPH + H+ → 2 GSH + NADP+.
Read more about this topic: Glutathione Peroxidase
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