[Study of the kinetics and mechanism of ATP hydrolysis by soluble ATPase of the chloroplasts (CFl) in the presence of Mg2+ ions].

A kinetic study of ATP hydrolysis by soluble ATPase of chloroplasts (CF1) was made. At low concentrations of MgCl2 a linear increase of the reaction rate was observed during the increase in the ATP concentration up to 1 mM. At high concentrations of MgCl2 the dependence was of a more complicated nature. At MgCl2 concentrations lower than 0.1 mM the reaction approached second-order kinetics with respect to Mg2+; the increase in MgCl2 concentration resulted in a decrease of the reaction order. It is assumed that MgATP is the "true" substrate and MgADP the "true" inhibitor of the reaction. A reaction mechanism of ATP hydrolysis is postulated.