FIGURE 4.

Phospholipid vesicle concentration-dependent superoxide formation under constant amounts of cytochrome c and ubiquinol. The superoxide generation was measured by the reduction of superoxide dismutase-sensitive acetylated cytochrome c reduction as described under “Experimental Procedures.” Solution A contains 100 mm Na⁺/K⁺ phosphate buffer, pH 7.4, 10.0 μm acetylated cytochrome c, and different concentrations of asolectin vesicle. Solution B contains 0.5 mm Na⁺/K⁺ phosphate buffer, pH 4, 250 μm Q-H₂ in the presence or absence of 300 units/ml superoxide dismutase. Each data point represents an average of four experiments. Error bars indicate S.D.