The rate constant of charge flow through F0 (see Fig. 2 B) as a function of the pH and the isotope composition of the medium (H2O: ○, D2O: •). Medium contained 20 mM glycylglycine, 20 mM sodium phosphate, 20 mM 4-morpholinepropanesulfonic acid (MES), 20 mM glycine, 50 mM KCl, 2 mM K4[Fe(CN)6], 5 μM DMF, 2 mM KCN, 3 μM myxothiazol. The solid line was calculated by the kinetic model of F0 conductance as described in the text with the parameters listed in Table 2.