FIG. 4.

Inhibition of the I. tartaricus ATPase by DCCD and protection from this inhibition by Na⁺ or Li⁺ ions. ATPase was incubated at 25°C in 50 mM potassium phosphate buffer, pH 7.0, with 200 μM DCCD and 2 mM NaCl (⧫), 20 mM LiCl (•), or 20 mM KCl (▴). The residual ATPase activity was determined with samples taken at the indicated times. DCCD was absent in the control (▪).