Contains FMN. The enzyme participates in heme b biosynthesis. In the bacterium Escherichia coli it interacts with either ubiquinone or menaquinone, depending on whether the organism grows aerobically or anaerobically.
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The expected taxonomic range for this enzyme is: Bacteria, Archaea, Eukaryota
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SYSTEMATIC NAME
IUBMB Comments
protoporphyrinogen IX:quinone oxidoreductase
Contains FMN. The enzyme participates in heme b biosynthesis. In the bacterium Escherichia coli it interacts with either ubiquinone or menaquinone, depending on whether the organism grows aerobically or anaerobically.
potential electron acceptors, i.e. 2, 6-dichloroindophenol, phenazine methosulfate, menadione, and vitamin K1, respectively, directly oxidize the substrate in the absence of HemG
membrane associated enzyme with substrates protoporphyrinogen IX and triphenyltetrazolium chloride, pH and temperature not specified in the publication
the FMN enzyme protoporphyrinogen IX oxidase (HemG) of Escherichia coli abstracts six electrons from its substrate and transfers them via ubiquinone, cytochrome bo3 and cytochrome bd oxidase to oxygen. Under anaerobic conditions electrons are transferred via menaquinone, fumarate and nitrate reductase. Cytochrome bo3 , cytochrome bd, and nitrate reductase contribute to the proton motive force that drives ATP formation
Escherichia coli strain SASX38 lacks functional protoporphyrinogen IX dehydrogenase activity and is reported to be deficient in HemG. Sequence analysis of the SASX38 hemG gene reveals a deletion from nucleotide 152 to 470. This results in a predicted HemG protein that remains in frame but lacks 106 internal amino acids, including the long chain insert loop
four electron transport chains from HemG via diverse quinones to cytochrome bo3, cytochrome bd, nitrate reductase, and fumarate reductase were reconstituted in vitro from purified components, overview
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PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
native enzyme solubilized from membranes by anion exchange chromatography, recombinant His-tagged enzyme from Bacillus megaterium byy affinity chromatography and gel filtration. Removal of the fused His-tag via protease digestion does not change the catalytic properties
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History
1.3.5.3 protoporphyrinogen IX dehydrogenase (quinone)
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