Figure 3.

Kinase activity of the purified KGUK from C. necator was measured at increasing concentrations of ATP, maintaining a constant excess of KG (1.25 mM) as the phosphate acceptor and 2.1 μg/mL of purified enzyme. ATP kinetics were carried out for kinetic constants calculation using a Mg²⁺ excess concentration of 5 mM (A). To evaluate the effect of higher concentrations of ATP on the enzyme activity, additional assays were performed increasing the Mg²⁺ concentration to 25 mM (B). When ATP concentrations over 5 mM were used, a strong decrease in the kinase activity was observed.