Figure 5.

Proton pumping and NADH-DBQ activities in ubiquinone-rich and menaquinone-rich DKO membranes reconstituted with purified E. coli complex I. DKO membranes are devoid of complex I (NDH-1) and NDH-2. (A) 5 μL of reconstituted complex I (1 mg/mL) in 1 mL of reconstitution buffer (50 mM MOPS, pH 7.0, 50 mM KCl, 20 mM MgCl₂) containing 0.2 μM ACMA dye was used for the H+ pumping assay. (B) Initial acidification rate was calculated from the initial slope of fluorescence quenching of ACMA.