Oxygen dependent electron transfer in the cytochrome bc1 complex

The effect of molecular oxygen on the electron transfer activity of the cytochrome bc1 complex was investigated by determining the activity of the complex under the aerobic and anaerobic conditions. Molecular oxygen increases the activity of Rhodobacter sphaeroides bc1 complex up to 82%, depending on the intactness of the complex. Since oxygen enhances the reduction rate of heme bL, but shows no effect on the reduction rate of heme bH, the effect of oxygen in the electron transfer sequence of the cytochrome bc1 complex is at the step of heme bL reduction during bifurcated oxidation of ubiquinol.

► The cytochrome bc1 catalyzes the electron transfer from ubiquinol to cytochrome c.
► The activity of cytochrome bc1 increases in the presence of molecular oxgyen.
► The electron transfer catalyzed by the cytochrome bc1 is oxygen dependent.
► The effect of oxygen is dependent on the intactness of the complex.
► The effect of oxygen is at the step of heme bL reduction.