The homogenate was centrifuged at
3070 g for 10 min. The supernatant was filtered through a Millipore
filter (0.22 mm). A volume of 1.0 mL of 100 mM potassium phosphate
buffer (pH 8.4) and 1.0 mL of the colorimetric reagent were
added to 100 mL of the supernatant.