Glutathione Peroxidase Assay

The brain homogenate (0.3 mL) was mixed with 10 mM sodium azide (0.1 mL), 0.1 mL of H₂O₂ (0.1 mL), 0.1 M phosphate buffer of pH 7.4 (0.3 mL), and 2 mM reduced glutathione (0.2 mL). After incubation for 0.25 h at 37 °C, 5% TCA (0.5 mL) was added to stop the reaction. The mixture was centrifuged at 1500 rpm for 5 min followed by the removal of the upper layer. The 0.1 mL of the separated layer was reacted with 0.7 mL of DTNB and 0.2 mL of Phosphate buffer and absorbance was measured at 420 nm.