Figure 3. Steady-state kinetics of ATP hydrolysis by the optimized catalytic domain.

(A) The ATP hydrolysis is inhibited above 4 mM ATP concentration. (B) The hydrolysis of ATP by the enzyme shows a positive cooperativity up to 4 mM ATP concentration. The kinetics of hydrolysis was measured by following phosphate release in 10 mM Tris, pH = 7.6, 150 mM NaCl, and 1 mM Mg⁺² at 37°C as described under Materials and Methods. Total protein concentration was 9.6 µg. Error bars correspond to standard deviation of triplicate measurements.