Catalase activity was determined by the method of Maehly and
Chance (1954), which monitors the disappearance of H2O2 by the
enzyme. The decrease in absorbance at 240 nm of a reaction mixture
containing 1 ml of 50 mM sodium phosphate buffer (pH 7.0),
0.5 ml of 0.5 mM H2O2, and 1 mL of crude protein extract, was calculated.
One unit of catalase activity is defined as the amount of
enzyme that decomposes 1 micromoles of H2O2 per minute per
milligram of protein under the conditions of the assay.