Radical metabolism is partner to energy metabolism in mitochondria

It has been shown that cytochrome c plays a role in scavenging O(2)(-). and H(2)O(2) in mitochondria through two electron leak pathways of the respiratory chain. Based on the two electron leak pathways and the superoxide metabolic routes in nature, it is suggested that the concept of radical metabolism should be added as a partner to the energy metabolism of mitochondria. A total of four reactive pathways of superoxide anion have been identified, collected, and linked to electron leaks in the respiratory chain. A view is presented that envisions mitochondria working on ATP synthesis by means of transferring electrons inside the respiratory chain while at the same time working on ROS generation and elimination as electrons leak out of the chain.