Fig. 4.

Proton uptake in everted membrane vesicles dependent on coenzyme F₄₂₀H₂:Fe(III) oxidoreductase activity. The reaction mixtures (2.0 ml) contained 40 mM KSCN, 0.4 M sucrose, 10 mM dithiothreitol and Fe(III)-loaded vesicles (0.5 mg protein) from methanol-grown cells in 2 mM potassium phosphate buffer (pH 7.0) and the indicated final concentration of reduced coenzyme F₄₂₀ (F₄₂₀H₂). Additional reagents were added as indicated with final concentrations shown. a Effect of dicyclohexylcarbodiimide (DCCD). b Effect of carbonyl cyanide m-chlorophenyl hydrazine (CCCP). c Effect of increasing concentrations of F₄₂₀H₂. The difference between the starting baseline and the final baseline represents alkalinization of the medium dependent on additions