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#hydrogen peroxide

7 public questions tagged with this topic.

Cell Organelles

Which enzyme in peroxisomes detoxifies H₂O₂?

Because peroxisomal oxidases produce stoichiometric hydrogen peroxide during oxidation of fatty acids, urate, D-amino acids and polyamines, cells require robust detoxification to prevent oxidative damage to proteins, lipids and DNA. Catalase is the signature antioxidant enzyme residing in peroxisomal matrix, often forming electron-dense crystalline core visible by electron microscopy in rat liver. It is a 240 kDa heme-containing homotetramer that disproportionates hydrogen peroxide into water and molecular oxygen with extremely high turnover number near ten million molecules per second, one of

Ref: Alberts et al., Molecular Biology of the Cell, 6th ed., Chapter 12: Peroxisomes and Catalase Function.

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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 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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