Fig. 1. Relationship between the rates of ${\mathbf{O}}_{\mathbf{2}}^{\overline{·}}$ generation by cardiac submitochondrial particles from different species and the amounts of CoQ₉ (A) and CoQ₁₀ (B), extractable from heart mitochondria.

The rates of ${\text{O}}_2^{\overline{·}}$ generation were measured as superoxide dismutase-inhibitable reduction of acetylated ferricytochrome c, as reported previously (12, 22). The reaction mixture contained 10 μM acetylated ferricytochrome c, 6 μM rotenone, 1.2 μM antimycin A, and 20 μg of SMP protein. Nonlinear regression analysis for the sigmoid curve fits was performed using 4-parameter logistic function (SigmaPlot 2.0; Jandel Corp., San Rafael, CA).