2.5. Standard assay for the determination of enzyme activities
with cell extract
The azo reductase assay mixture contained 50 mM phosphate buffer (pH
7.0), 2 mM NADH, 150M of Amaranth, Fast Red E, Ponceau S and 100l of
enzyme in 1 mL of reaction mixture [1]. This reaction mixture was pre-incubated
for 3 min followed by the addition of NADH and monitored for the decrease in
colour absorbance at room temperature (40 ◦C). One unit of enzyme activity
was defined as the amount of enzyme catalyzing the decolourization of 1mol
substrate per minute. The protein content of cell extracts was determined by
using Bovine serum albumin as the standard [1