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- Name help_outline menaquinone-8 Identifier CHEBI:44027 (CAS: 523-38-6) help_outline Charge 0 Formula C51H72O2 InChIKeyhelp_outline LXKDFTDVRVLXFY-WQWYCSGDSA-N SMILEShelp_outline CC(C)=CCC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC1=C(C)C(=O)c2ccccc2C1=O 2D coordinates Mol file for the small molecule Search links Involved in 18 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline protoporphyrinogen IX Identifier CHEBI:57307 Charge -2 Formula C34H38N4O4 InChIKeyhelp_outline UHSGPDMIQQYNAX-UHFFFAOYSA-L SMILEShelp_outline Cc1c2Cc3[nH]c(Cc4[nH]c(Cc5[nH]c(Cc([nH]2)c1CCC([O-])=O)c(CCC([O-])=O)c5C)c(C=C)c4C)c(C=C)c3C 2D coordinates Mol file for the small molecule Search links Involved in 8 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline menaquinol-8 Identifier CHEBI:61684 Charge 0 Formula C51H74O2 InChIKeyhelp_outline OIEZRVBFVPGODT-WQWYCSGDSA-N SMILEShelp_outline CC(C)=CCC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC\C(C)=C\CC\C(C)=C\Cc1c(C)c(O)c2ccccc2c1O 2D coordinates Mol file for the small molecule Search links Involved in 19 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline protoporphyrin IX Identifier CHEBI:57306 (Beilstein: 3897489,9313467) help_outline Charge -2 Formula C34H32N4O4 InChIKeyhelp_outline KSFOVUSSGSKXFI-UJJXFSCMSA-L SMILEShelp_outline Cc1c(CCC([O-])=O)c2cc3[nH]c(cc4nc(cc5[nH]c(cc1n2)c(C)c5C=C)c(C)c4C=C)c(C)c3CCC([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 9 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:30575 | RHEA:30576 | RHEA:30577 | RHEA:30578 | |
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Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Nitrate, fumarate, and oxygen as electron acceptors for a late step in microbial heme synthesis.
Jacobs N.J., Jacobs J.M.
Nitrate can serve as anaerobic electron acceptor for the oxidation of protoporphyrinogen to protoporphyrin in cell-free extracts of Escherichia coli grown anaerobically in the presence of nitrate. Two kinds of experiments indicated this: anaerobic protoporphyrin formation from protoporphyrinogen, ... >> More
Nitrate can serve as anaerobic electron acceptor for the oxidation of protoporphyrinogen to protoporphyrin in cell-free extracts of Escherichia coli grown anaerobically in the presence of nitrate. Two kinds of experiments indicated this: anaerobic protoporphyrin formation from protoporphyrinogen, followed spectrophotometrically, was markedly stimulated by addition of nitrate; and anaerobic protoheme formation from protoporphyrinogen, determined by extraction procedures, was markedly stimulated by addition of nitrate. In contrast, anaerobic protoheme formation from protoporphyrin was not dependent upon addition of nitrate. This was the first demonstration of the ability of nitrate to serve as electron acceptor for this late step of heme synthesis. Previous studies with mammalian and yeast mitochondria had indicated an obligatory requirement for molecular oxygen at this step. In confirmation of our previous preliminary report, fumarate was also shown to be an electron acceptor for anaerobic protoporphyrinogen oxidation in extracts of E. coli grown anaerobically on fumarate. For the first time, anaerobic protoheme formation from protoporphyrinogen, but not from protoporphyrin, was shown to be dependent upon the addition of fumarate. The importance of these findings is 2-fold. First, they establish that enzymatic protoporphyrinogen oxidation can occur in the absence of molecular oxygen, in contrast to previous observations using mammalian and yeast mitochondria. Secondly, these findings help explain the ability of some facultative and anaerobic bacteria to form very large amounts of heme compounds, such as cytochrome pigments, when grown anaerobically in the presence of nitrate or fumarate. In fact, denitrifying bacteria are known to form more cytochromes when grown anaerobically than during aerobic growth. An unexpected finding was that extracts of another bacterium, Staphylococcus epidermidis, exhibited very little ability to oxidize protoporphyrinogen to protoporphyrin as compared to E. coli extracts. This finding suggests some fundamental differences in these two organisms in this key step in heme synthesis. It is known that these two facultative organisms also differ in that E. coli synthesizes cytochrome during both aerobic and anaerobic growth, while Staphylococcus only synthesizes cytochromes when grown aerobically. << Less
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Heme biosynthesis is coupled to electron transport chains for energy generation.
Moebius K., Arias-Cartin R., Breckau D., Haennig A.L., Riedmann K., Biedendieck R., Schroeder S., Becher D., Magalon A., Moser J., Jahn M., Jahn D.
Cellular energy generation uses membrane-localized electron transfer chains for ATP synthesis. Formed ATP in turn is consumed for the biosynthesis of cellular building blocks. In contrast, heme cofactor biosynthesis was found driving ATP generation via electron transport after initial ATP consumpt ... >> More
Cellular energy generation uses membrane-localized electron transfer chains for ATP synthesis. Formed ATP in turn is consumed for the biosynthesis of cellular building blocks. In contrast, heme cofactor biosynthesis was found driving ATP generation via electron transport after initial ATP consumption. The FMN enzyme protoporphyrinogen IX oxidase (HemG) of Escherichia coli abstracts six electrons from its substrate and transfers them via ubiquinone, cytochrome bo(3) (Cyo) and cytochrome bd (Cyd) oxidase to oxygen. Under anaerobic conditions electrons are transferred via menaquinone, fumarate (Frd) and nitrate reductase (Nar). Cyo, Cyd and Nar contribute to the proton motive force that drives ATP formation. Four electron transport chains from HemG via diverse quinones to Cyo, Cyd, Nar, and Frd were reconstituted in vitro from purified components. Characterization of E. coli mutants deficient in nar, frd, cyo, cyd provided in vivo evidence for a detailed model of heme biosynthesis coupled energy generation. << Less
Proc. Natl. Acad. Sci. U.S.A. 107:10436-10441(2010) [PubMed] [EuropePMC]
This publication is cited by 3 other entries.
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Evidence for involvement of the electron transport system at a late step of anaerobic microbial heme synthesis.
Jacobs N.J., Jacobs J.M.
The penultimate step in heme biosynthesis, the oxidation of protoporphyrinogen to protoporphyrin, can be anaerobically coupled to the reduction of fumarate in extracts of anaerobically-grown Escherichia coli. This coupling is approximately 90% inhibied by 2-heptyl-4-hydroxy quinoline-N-oxide (HQNO ... >> More
The penultimate step in heme biosynthesis, the oxidation of protoporphyrinogen to protoporphyrin, can be anaerobically coupled to the reduction of fumarate in extracts of anaerobically-grown Escherichia coli. This coupling is approximately 90% inhibied by 2-heptyl-4-hydroxy quinoline-N-oxide (HQNO), a known inhibitor of the electron transport chain. This observation suggests that the mechanism of the anaerobic oxidation of protoporphyrinogen in E. coli involves a coupling into the anaerobic electron transport system. In contrast, the aerobic oxidation of protoporphyrinogen, which occurs in mammalian and yeast mitochondria, is known to be linked directly to oxygen without the mediation of an electron transport system. << Less