Activation of NeuTTM PPPase by divalent cations. A, shown is dependence of PPPase activity on Mg2+ (○) and Mn2+ (●) total concentration. The incubation was carried out in the presence of 50 mm Na-CHES (Mg2+, pH 9.7) or Na-CAPS (Mn2+, pH 10.4) at 37 °C. B, shown is the effect of increasing concentrations of Co2+ (calculated free Co2+ concentration assuming Kd = 8 nm for the Co-PPPi complex) on the PPPase activity. Conditions of experiment: PPPi, 0.5 mm; Na-CHES, 50 mm, pH 9.5, 45 °C. Results are the mean ± S.D, n = 3.