Aggregate rate of H2O2 [hydrogen peroxide] formation in aerobic E. coli and O2− [superoxide] formation rate

Range H2O2 formation rate 10–15 μM per second: O2− formation rate ~5 μM per second μM per second
Organism Bacteria Escherichia coli
Reference Imlay JA. The molecular mechanisms and physiological consequences of oxidative stress: lessons from a model bacterium. Nat Rev Microbiol. 2013 Jul11(7):443-54. doi: 10.1038/nrmicro3032. p.444 right column bottom paragraphPubMed ID23712352
Primary Source [14] Seaver, L. C. & Imlay, J. A. Are respiratory enzymes the primary sources of intracellular hydrogen peroxide? J. Biol. Chem. 279, 48742–48750 (2004). DOI: 10.1074/jbc.M408754200 [22] Imlay, J. A. & Fridovich, I. Assay of metabolic superoxide production in Escherichia coli. J. Biol. Chem. 266, 6957–6965 (1991).PubMed ID15361522, 1849898
Method Primary source [14] abstract: "To quantify H2O2 formation, [investigators] have generated strains of Escherichia coli that lack intracellular scavenging enzymes." Primary source [22] abstract: "Superoxide production has been measured in subcellular fractions of SOD [Superoxide dismutase]-deficient Escherichia coli provided with physiological reductants."
Comments P.444 right column bottom paragraph: "Only 0.1–1% of the electron flux through any particular enzyme is likely to be intercepted by O2. However, measurements of H2O2 efflux from scavenger-deficient cells indicate that the aggregate rate of H2O2 formation inside aerobic E. coli is 10–15 μM per second (primary Source 14). O2− formation is estimated to be about 5 μM per second, on the basis of in vitro studies [primary Source 22]. Because O2− and H2O2 react rapidly with vulnerable targets (see below), these rates are high enough to require the synthesis of ample scavenger enzymes (Box 2)."
Entered by Uri M
ID 112943