Figure 1: The dark cycles are the enzymes involved in ATP synthesis of mitochondria. Green color arrows show the way of electron transfer in the respiratory chain. Yellow color shows the Mitchell’s theory on the coupling mechanism of respiratory chain and ATPase. The red colored part shows the four electron leak pathways established in our lab. As the involvement of reductive route(O2 →O2 -. →H2O2 →H2O), the electron leakage is defined as the radical metabolism partner to ATP production. Oxygen consumed in the electron leakage is not used in ATP production but spent in the generation of reactive oxygen species (ROS) such as O2 -. H2O2 HOO·and ONOO-.