FIGURE 4.

Biochemical properties of the purified MbbrA₁A_o-ATP synthase. Effect of ATP (A) and MgCl₂ (B) on ATPase activity. ATP hydrolysis assays were performed at pH 6.5 with 7.5 μg of purified MbbrA₁A_o in the presence of 125 mm NaCl using a colorimetric assay that measured the amount of inorganic phosphate liberated at 37 °C. C, effect of NaCl on ATPase activity at pH 6.5 (open circles) and pH 8.5 (closed circles). ATP hydrolysis was performed with 7.5 μg of purified A₁A_o-ATP synthase using the potassium salt of ATP. D, stability of the purified MbbrA₁A_o at 4 °C in 0.05% (w/v) DDM (closed squares) and MbbrA₁A_o in E. coli membrane vesicles (open circles).