All cells living in aerobic habitats contain soluble superoxide dismutase enzymes (SODs) disproportionating superoxide to molecular oxygen and hydrogen peroxide, which in turn is detoxified by catalases or peroxidases. Remarkably, this mechanism discovered half a century ago has remained the only identified protection against superoxide in biology.

Scientists at the department of biochemistry and biophysics, Stockholm University in collaboration with a group at Universität Bern, Switzerland, have now discovered a new mechanism for superoxide quenching in biology. A protein embedded in the cell membrane is capable of directly stripping an electron from superoxide, producing harmless oxygen. The electron is then funneled to ubiquinone, the carrier of electrons in the cell’s energy conversion machinery.


-It is very exciting to see a completely new biochemical pathway. It is also such an elegant mechanism; the energy is preserved by reducing the quinone pool and building membrane potential. Moreover no secondary reactive oxygen species, such as peroxide, is produced. We are now very interested to see if this mechanism is also active in humans and how it in that case influences the effects of superoxide in our cells says Martin Högbom, professor of structural biochemistry at Stockholm University.


The study: ”Scavenging of superoxide by a membrane bound superoxide oxidase” has been financed by the  Knut and Alice Wallenberg foundation, the Swedish foundation for strategic research and the Swedish research council


Scavenging of superoxide by a membrane bound superoxide oxidase

Nature Chemical Biology, DOI: 10.1038/s41589-018-0072-x.