Catalase (CAT) activity
Catalase (CAT) activity was determined by monitoring the decomposition of H2O 2at 240 nm following the method of Aebi (1984). The reaction mixture contained 1.7mL 50 mmol/L sodium phosphate buffer (pH 7.0), 1 mL double distilled water and 0.2 mL tissue extract. The reaction was initiated by adding 0.1 mL 100 mmol/L H2O2.One unit of catalase was defined as the amount of enzyme which caused a 0.01 decrease of A240 per min at 25oC.