Glutathione peroxidase
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GlutPeroxidase-1GP1.png
The enzyme glutathione peroxidase ( PDB 1GP1 (http://www.rcsb.org/pdb/cgi/explore.cgi?pid=60591045867525&pdbId=1GP1), EC 1.11.1.9 (http://www.expasy.org/cgi-bin/nicezyme.pl?1.11.1.9)) is a peroxidase found in the erythrocytes of mammals, which helps prevent lipid peroxidation of cell membranes by consuming free peroxide in the cell. The summary reaction the enzyme catalyzes is:
- 2GSH + H2O2 → GSSG + 2H2O
Where GSH represents reduced monomeric glutathione, and GSSG represents oxidized glutathione. Glutathione reductase then reduces the oxidized glutathione to complete the cycle:
- GSSG + NADPH + H+ → 2 GSH + NADP+
Glutathione peroxidase is a tetramer, and the bovine erythrocyte enzyme has a molecular weight of 84,000. It is a selenium containing enzyme with 4 selenocysteine amino acid residues that participate in the actual mechanism of this enzyme.