150μL of the working mixture which comprises of
8 mL of 1× assay buffer was added to 228μL of the diluted enzyme
solution (6 units/L and 228μL of DTNB stock solution (1.5 mg/mL) to
each well and re-suspended. After incubation for 5 min at room
temperature, 50μL of the diluted NADPH solution was added and
then mixed to generate a yellow colour. The absorbance of reduced
glutathione was measured at 412 nm and calculated by subtracting
the final absorbance from the blank. The values of the glutathione
standard solutions were used to determine the standard curve and
theΔA412/min equivalent was calculated to 1 nmol of reduced glutathione per well. The activity of the enzyme was expressed as percentage
(%)