The reaction mixture consisted of 1.5 mL of 0.1875 mmol L1 EDTA-Na, 1 mL of 1.5 mmol L1 ascorbic acid, 50 mL of 0.3 mmol L1 H2O2, and 200 mL of enzyme extract. The reaction was initiated by adding H2O2 and the change of absorbance at 290 nm was recorded