Oxygen dependent electron transfer in the cytochrome bc1 complex

Abstract The effect of molecular oxygen on the electron transfer activity of the cytochrome bc 1 complex was investigated by determining the activity of the complex under the aerobic and anaerobic conditions. Molecular oxygen increases the activity of Rhodobacter sphaeroides bc 1 complex up to 82%, depending on the intactness of the complex. Since oxygen enhances the reduction rate of heme b L , but shows no effect on the reduction rate of heme b H , the effect of oxygen in the electron transfer sequence of the cytochrome bc 1 complex is at the step of heme b L reduction during bifurcated oxidation of ubiquinol.