Fig. 2.

Rate of ATP synthesis and hydrolysis as a function of the transmembrane ΔpH. The initial rates and their errors obtained from Fig. 1, and additional measurements, were plotted as a function of ΔpH. Some error bars are not visible, because they are smaller than the size of the symbols. Each curve represents catalysis rates measured at a constant stoichiometric product, Q. The data were fitted, using their errors as weight, by a function that was the product of a linear function (describing the rate-force relation near equilibrium) and of a sigmoidal function (describing the ΔpH dependence of activation). The fitting functions were used to interpolate the point at which the rate is zero [ΔpH(eq)]. (Left) CF₀F₁ proteoliposomes. (Right) EF₀F₁ proteoliposomes.