Figure 7.
A, Inhibition of AGPase activity by phosphate. The activity of AGPase was measured using the forward reaction in the presence of varying concentrations of Pi at several fixed concentrations of 3-PGA: 1 mm (▴), 2.5 mm (•), 5 mm (▾), and 10 mm (♦). The Ki for Pi was determined from the X intercept at each 3-PGA concentration. B, Determination of the binding constant of Pi in the absence of 3-PGA. A plot of Ki versus 3-PGA concentration was used to determine the binding constant of Pi in the absence of 3-PGA.