Figure 6.

Inhibition of membrane ATPase activity from mutant and wild-type ATP synthase enzymes by fluoroaluminate, fluoroscandium, and azide. Membranes were preincubated for 60 min at room temperature with 1 mM MgADP, 10 mM NaF, and the indicated concentration of AlCl₃ (A) or ScCl₃ (B). Then aliquots were added to 1 mL of assay buffer, and ATPase activity was determined. Sodium azide was added directly to the membranes and incubated for 30 min before the assay (C) (for details, see Materials and Methods). Symbols: (★) wild type, (○) αT349A, (□) αT349D, (◇) αT349Q, (△) αT349R, (▽) βR182A, and (☆) αT349R/βR182A. All the data points are means of at least four different experiments using two or three independent membrane preparations of each mutant. The variation was ±10% between different experiments.