FIGURE 4.

Relationships between the steady-state reduction of cytochromes b₅₆₂ and b₅₆₆ in the absence and presence of ATP. Cytochrome b₅₆₆ was measured at 566–575 nm with correction for cytochrome b₅₆₂ by subtracting 50% of the signal at 561–569 nm. Cytochrome b₅₆₂ was measured at 561–569 nm. a, ATP absent, conditions as Fig. 1e. b, 2 mm ATP present, conditions as Fig. 3. Solid curves indicate the best fits of Equation 3, plotted with the relevant values of E_dif^m, see “Experimental Procedures.”