ATP- and NADH-dependent ferredoxin reduction at inverted membrane vesicles. For measurement of ferredoxin reduction at 430 nm, membrane vesicles (50 μg) were incubated in 1 ml of 100 mm Tris (pH 7.5), 5 mm MgCl2, 2 mm NaCl, 30 μm ferredoxin, 2 mm DTE, and 2 μm resazurin in a nitrogen atmosphere. The reaction was started by the addition of 2 mm ATP. ETH2120 was added at a concentration of 10 μm. The data shown are representative of three experiments using independent inverted membrane vesicle preparations.