May constitute a glutathione peroxidase-like protective system against oxidative stresses. Hydrogen peroxide, tert-butyl hydroperoxide and cumene, but not phosphatidylcholine hydroperoxide, can act as acceptors. 2 glutathione + H2O2 = glutathione disulfide + 2 H2O By selenium, particularly under autotrophic conditions. Belongs to the glutathione peroxidase family.