Fig. 3

The inhibition of the electron flow in complex III by litreol involves cytochrome b. Reduction in cytochromes b and c₁ was measured by spectrophotometry in submitochondrial particles and cytochrome c, as described in “Methods” section. The reaction was initiated by adding 0.17 mM NADH and was monitored at 563–577 nm for cytochrome b (a) and 550–535 nm for cytochrome c (b). The time of each cycle was 20 s, and the reading time was 0.5 s. NADH and litreol were added after 9 and 18 cycles, respectively, as indicated by the respective arrows; in total, 50 cycles were completed. The results are representative of four independent experiments. c, d Hanes-Woolf kinetics of the reduction of cyt c in the presence of litreol and antimycin A. Duroquinol and cyt c were used respectively as electron donor and electron acceptor. The results from the Hanes-Woolf analysis indicate that the inhibition was noncompetitive for cyt c