Complex III can also release O 2 − into the intermembrane space. Complex I, II, and III release O 2 − into the mitochondrial matrix where SOD2 rapidly converts it into H 2O 2. These complexes generate O 2 − by the one-electron reduction of molecular O 2. The three best characterized sites are complex I, II and III within the mitochondrial respiratory chain, which is located in the inner mitochondrial membrane. There are eight sites in mitochondria that produce ROS. Where are ROS generated in the cell? The two main sources of ROS associated with cell signaling are mitochondria and the family of NADPH oxidases (NOXs) ( Figure 1). In the presence of ferrous or cuprous ions, H 2O 2 can become a hydroxyl radical, which is very reactive and causes oxidation of lipids, proteins and DNA, resulting in damage to the cell. Unlike O 2 −, H 2O 2 can readily diffuse through membranes, making it an ideal intracellular signaling molecule. The concentration of H 2O 2 associated with signaling is likely in the low nanomolar range. O 2 − is rapidly converted by superoxide dismutases (SODs) into H 2O 2, which can impinge on cellular signaling by interacting with thiols within proteins. O 2 − is produced during oxidative metabolism by the one-electron reduction of molecular O 2. Each ROS has different intrinsic chemical properties, which dictate its reactivity and preferred biological targets. ROS are more chemically reactive than O 2 and are able to trigger various biological events. ROS include the superoxide anion (O 2 −), hydrogen peroxide (H 2O 2), as well as hydroxyl radicals (OH What are ROS? Reactive oxygen species (ROS) are intracellular chemical species that contain oxygen (O 2) and are reactive towards lipids, proteins and DNA. Molecular Therapy Nucleic Acids ( partner).Molecular Therapy Methods & Clinical Development ( partner).Human Genetics and Genomics Advances ( partner).American Journal of Human Genetics ( partner).

Cellular ros