Figure 1
Effect of NaCl concentration and pH of the growth medium on ATPase activity. Membrane vesicles were prepared from cells grown at different NaCl concentrations (A) at pH 7.6 (closed circle) or pH 9.0 (closed square), and at different pHs (B) at 0.5 M NaCl (open circle) or 2.0 M NaCl (open square). ATPase activity was assayed in the mixture containing 20 mM Tris-HCl pH 7.6, 5 mM MgCl2, 10 mM NaCl and membrane vesicles (30 μg protein). The reaction was started by the addition of 4 mM ATP (Tris salt). All data are the average of three independent experiments with vertical bars representing standard errors.