Glutathione peroxidase which may protect the cell from oxidative damage. 2 glutathione + H2O2 = glutathione disulfide + 2 H2O Inhibited by Cu(2+), SDS and DTT. Activity is slightly increased by Fe(2+), Mn(2+), triton X-100 and EDTA. Optimum pH is 6. Optimum temperature is 40 degrees Celsius. Belongs to the glutathione peroxidase family.