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#peroxidase

3 public questions tagged with this topic.

Microbial Physiology

Which bacterial enzyme neutralizes hydrogen peroxide?

Reactive oxygen species detoxification crucial for aerobic life. Hydrogen peroxide generated by flavoprotein oxidases and superoxide dismutase dismutation attacks iron sulfur clusters and via Fenton produces hydroxyl radical damaging DNA. Catalase provides efficient removal without reducing equivalents, dismutating two H2O2 to two water and one O2 through heme mediated cycle. Enzyme architecture tetrameric each subunit 60 kDa heme b, NADPH bound protecting against inactivation. Reaction proceeds two steps: oxidation of ferric heme to Compound I oxyferryl porphyrin cation radical by first H2O2,

Ref: Madigan et al., Brock Biology of Microorganisms, Chapter 6: Catalase neutralizes H2O2.

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Microbial Physiology

Which bacterial enzyme neutralizes hydrogen peroxide?

Hydrogen peroxide is unavoidable byproduct of flavoprotein oxidases such as NADH oxidase and autoxidation of menaquinones generating reactive oxygen stress capable of hydroxyl radical formation via Fenton reaction damaging iron-sulfur clusters and DNA. Aerobic bacteria depend on extremely efficient enzymatic detoxification. Catalase is tetrameric heme enzyme containing heme b active site where first H2O2 oxidizes ferric heme to Compound I ferryl oxo porphyrin radical, second H2O2 reduces Compound I releasing water and dioxygen. Catalytic rate is among highest known about ten million molecules

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 12: Catalase Function and Hydrogen Peroxide Neutralization.

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Microbial Physiology

Which enzyme neutralizes hydrogen peroxide (H₂O₂) in bacterial cells?

Hydrogen peroxide at even low micromolar concentrations of 1 to 2 micromolar causes inactivation of mononuclear iron enzymes and iron-sulfur dehydratases such as fumarase via Fenton chemistry generating highly reactive hydroxyl radicals that oxidize DNA generating 8-oxoguanine and protein carbonyls leading to mutagenesis. Bacteria deploy specialized scavenging enzymes for peroxide detoxification. Catalases are predominantly heme-containing tetrameric enzymes containing protoheme IX or heme b in each active site that dismutate two molecules of H2O2 into water and molecular oxygen with extremely

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 12: Catalase and Hydrogen Peroxide Detoxification.

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