<Tr> <Th> PubMed </Th> <Td> articles </Td> </Tr> <Tr> <Th> NCBI </Th> <Td> proteins </Td> </Tr> <P> Superoxide dismutase (SOD, EC 1.15. 1.1) is an enzyme that alternately catalyzes the dismutation (or partitioning) of the superoxide (O) radical into either ordinary molecular oxygen (O) or hydrogen peroxide (H O). Superoxide is produced as a by - product of oxygen metabolism and, if not regulated, causes many types of cell damage . Hydrogen peroxide is also damaging and is degraded by other enzymes such as catalase . Thus, SOD is an important antioxidant defense in nearly all living cells exposed to oxygen . One exception is Lactobacillus plantarum and related lactobacilli, which use a different mechanism to prevent damage from reactive (O). </P> <P> SOD enzymes deal with the superoxide radical by either adding or removing an electron from the superoxide molecules it encounters, thus changing the O into one of two less damaging species: either molecular oxygen (O) or hydrogen peroxide (H O). This SOD - catalyzed dismutation of superoxide may be written, for Cu, Zn SOD, with the following reactions: </P>

Where is superoxide dismutase found in the body