Two sources of endogenous hydrogen peroxide in Escherichia coli.

ABSTRACT: Mechanisms of hydrogen peroxide generation in Escherichia coli were investigated using a strain lacking scavenging enzymes. Surprisingly, the deletion of many abundant flavoenzymes that are known to autoxidize in vitro did not substantially lessen overall H(2)O(2) formation. However, H(2)O(2) production diminished by 25-30% when NadB turnover was eliminated. The flavin-dependent desaturating dehydrogenase, NadB uses fumarate as an electron acceptor in anaerobic cells. Experiments showed that aerobic NadB turnover depends upon its oxidation by molecular oxygen, with H(2)O(2) as a product. This reaction appears to be mechanistically adventitious. In contrast, most desaturating dehydrogenases are associated with the respiratory chain and deliver electrons to fumarate anaerobically or oxygen a

SUBMITTER: Korshunov S 

PROVIDER: S-EPMC3049997 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature