Figure 8.

Changes in ΔpH of proteoliposome lumen detected with the ΔpH probe acridine orange. (A) Effect of ATP concentration and effectors (CCCP and permeant anion NO^-₃) on alkalization of proteoliposome lumen. 100 mM NaCl was initially present in the reaction mixture containing 0.5 M sorbitol, 10 mM Hepes-Tris buffer pH 7.6, 1 μM acridine orange and proteoliposomes (25 μg protein). After 15 min incubation of proteoliposomes in the mixture, the reaction was run by the addition of ATP at various concentrations and effectors (CCCP at 12 μM or KNO₃ at 100 mM) as shown by the arrows. (B) Effect of cations on alkalization of proteoliposome lumen. NaCl was initially present in the reaction mixture at the concentration of 8 mM. The reaction was run by the addition of ATP at 4 mM and cations (chloride salts) at 100 mM as shown by the arrows.