FIGURE 3.

Inhibition of membrane-bound wild type and mutant ATP synthase by NBD-Cl. The membranes were preincubated for 60 min at room temperature with varied concentration of NBD-Cl, and then aliquots added to 1 ml of assay buffer and ATPase activity were determined. The details are given under “Materials and Methods.” •, wild type; ○, αS347A; □, αS347Q; ▵, αG351Q. Each data point represents an average of at least four experiments, using two independent membrane preparations of each mutant. The results agreed within ±10%.