Activity staining of glutathione peroxidase after electrophoresis on native and sodium dodecyl sulfate polyacrylamide gels

Glutathione peroxidase (GSH‐Px), from commercial bovine erythrocytes or ammonium sulfate fractionations (30–45%, 45–60%, 60–75% and 75–90% saturations) of ginger rhizome, was detected on polyacrylamide gels after native polyacrylamide gel electrophoresis (PAGE) or sodium dodecyl sulfate (SDS)‐PAGE. The gel was submerged in a 50 mM Tris‐HCl buffer (pH 7.9) containing 13 mM glutathione and 0.004% hydrogen peroxide with gentle shaking for 10–20 min. The GSH‐Px activity was stained with a solution containing 1.2 mM 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) and 1.6 mM phenazine methosulfate (PMS) for 10 min. The clear zone of GSH‐Px activity on a purple background was found in both native and SDS‐PAGE gels. This fast and sensitive method can be used in the process of enzyme purification and characterization of mammalian or plant cells.