The free-radical theory of aging was proposed more than 50 years ago. As one of the most
popular mechanisms explaining the aging process, it has been extensively studied in
several model organisms. However, the results remain controversial. The mitochondrial
version of free-radical theory of aging proposes that mitochondria are both the primary
sources of reactive oxygen species (ROS) and the primary targets of ROS-induced damage.
One critical ROS is hydrogen peroxide, which is naturally degraded by catalase in …