Figure 5.

Effect of varying ADP concentrations on the activity of AThTP-synthesizing enzyme at a fixed ThDP concentration of 0.1 mM and 10 mM Mg²⁺. The results are the mean ± SD for 3 to 6 experiments. The line was obtained by nonlinear regression assuming a sigmoid dose-response curve with an EC₅₀ of 0.08 mM. The inset shows a Hill plot obtained for ADP concentrations ranging from 0.04 to 0.6 mM. The Hill coefficient (n_H = 2.1) was calculated from the slope of the regression line over the linear portion of the graph (0.01 – 0.20 mM ADP).