FIGURE 3.

Generation of a proton gradient by complex I and the E183H^F variant. The proteins were reconstituted in proteoliposomes, and the ACMA fluorescence was monitored (28). The reaction of complex I (a) and the E183H^F variant (c) was started by adding either NADH (black curve) or NADPH (red curve) as indicated. The addition of NADPH to proteoliposomes containing complex I did not lead to the generation of a detectable proton gradient. As a control, either CCCP or piericidin A was added to the complex (b) before the reaction was started with the addition of NADH and to the variant (d) before the reaction was started with either NADH or NADPH.