Glutathione peroxidase

The enzyme glutathione peroxidase ( PDB 1GP1, EC 1.11.1.9) is found in the erythrocytes of mammals, and helps prevent 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.