Frontiers Evidence that protein thiols are not primary targets of intracellular reactive oxygen species in growing Escherichia coli The redox rhythm gates immune induced cell death distinctly from the genetic clock PNAS Sigma Aldrich Glutathione Peroxidase from bovine erythrocytes, CAS 9013 66 5, lyophilized powder, 300 units mg protein 100 units Measurement of superoxide dismutase, catalase and glutathione peroxidase in cultured cells and tissue Nature Protocols