Peroxiredoxin
| Peroxiredoxin | ||
|---|---|---|
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| Decamer of the AhpC from Salmonella typhimurium , a bacterial peroxiredoxin - according to PDB 1YEX | ||
| Enzyme classification | ||
| EC, category | 1.11.1.15 , oxidoreductase | |
| Response type | Redox reaction | |
| Substrate | R-OOH (+ Enzyme-Cys) | |
| Products | R-OH (+ enzyme-Cys-OH) | |
| Occurrence | ||
| Parent taxon | Creature | |
Peroxiredoxin (in detail according to IUBMB : thiol-containing-reductant: hydroperoxide oxidoreductase ) is an enzyme that occurs in all living things. In the reduced state , it catalyzes the reduction of hydroperoxides (R-OOH) to the corresponding alcohol (R-OH), whereby it is itself oxidized on a cysteine residue ; In a second step, the original state is restored through the simultaneous oxidation of a thiol , usually thioredoxin . Hydroperoxides are harmful by-products of oxygen breathing and are among the reactive oxygen species ; reduced peroxiredoxin therefore acts as an antioxidant . Six different peroxiredoxins are known in humans, which are encoded by the genes PRDX1 to PRDX6 , have between approximately 200 and 270 amino acids and can occur as monomers, dimers or oligomers.
Catalyzed reaction
First the hydroperoxide is reduced, with simultaneous oxidation of the peroxiredoxin. In detail, a special cysteine residue of peroxiredoxin results in a sulfenic acid , which combines with another cysteine residue (which is in the same polypeptide or the dimer partner) to form a Cys-SS-Cys disulfide bridge with elimination of water .
Later, peroxiredoxin is reduced back with thioredoxin, more precisely the disulfide is reduced to the dithiol. The necessary hydrogen atoms come from the dithiol of thioredoxin, which in turn has a disulfide bridge after oxidation.