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Literature summary for 1.3.8.1 extracted from
- Studies on the mechanism of electron bifurcation catalyzed by electron transferring flavoprotein (Etf) and butyryl-CoA dehydrogenase (Bcd) of Acidaminococcus fermentans (2014), J. Biol. Chem., 289, 5145-5157 .
Crystallization (Commentary)
| Crystallization (Comment) | Organism |
|---|---|
| purified enzyme, mixing of 15 mg/ml protein solution with 225% PEG 1500, 10% SPG buffer, pH 9.0, at 4°C, X-ray diffraction structure determination and analysis at 1.8 A resolution | Acidaminococcus fermentans |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| additional information | - |
additional information | the tight non-dissociating bifurcating Etf-Bcd complex of Closstridium difficile exhibits normal Michaelis-Menten kinetics for NADH | Acidaminococcus fermentans | |
| 0.145 | - |
NADH | pH and temperature not specified in the publication | Acidaminococcus fermentans |  |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| crotonyl-CoA + 2 NADH + 2 Fd- | Acidaminococcus fermentans | - |
butyryl-CoA + 2 NAD+ + 2 Fd2- | - |
? | |
| crotonyl-CoA + 2 NADH + 2 Fd- | Acidaminococcus fermentans VR4 | - |
butyryl-CoA + 2 NAD+ + 2 Fd2- | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Acidaminococcus fermentans | D2RIQ3 | - |
- |
| Acidaminococcus fermentans | D2RIQ3 and D2RL84 | D2RIQ3 i.e. flavoprotein alpha subunit, D2RL84 i.e. acyl-CoA dehydrogenase domain protein | - |
| Acidaminococcus fermentans ATCC 25085 | D2RIQ3 and D2RL84 | D2RIQ3 i.e. flavoprotein alpha subunit, D2RL84 i.e. acyl-CoA dehydrogenase domain protein | - |
| Acidaminococcus fermentans VR4 | D2RIQ3 | - |
- |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| native enzyme from strain VR4 cell supernatant by ultracentrifugation, ammonium sulfate fractionation, dialysis, anion exchange chromatography, and ultrafiltration, the the enzyme is mixed with excess of solid dithionite under anaerobic conditions to give the yellow form, and further purified by desalting gel filtration under anaerobic conditions | Acidaminococcus fermentans |
Reaction
| Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|
| a short-chain acyl-CoA + electron-transfer flavoprotein = a short-chain trans-2,3-dehydroacyl-CoA + reduced electron-transfer flavoprotein | bifurcating electron transferring flavoprotein (EtfAf) and butyryl-CoA dehydrogenase (BcdAf) of Acidaminococcus fermentans,which couple the exergonic reduction of crotonyl-CoA to butyryl-CoA to the endergonic reduction of ferredoxin both with NADH. EtfAf contains one FAD (alpha-FAD) in subunit alpha and a second FAD (beta-FAD) in subunit beta. The distance between the two isoalloxazine rings is 18 A. The EtfAf-NAD+ complex structure revealed beta-FAD as acceptor of the hydride of NADH. The formed beta-FADH- is considered as the bifurcating electron donor. As a result of a domain movement, alpha-FAD is able to approach beta-FADH- by about 4 A and to take up one electron yielding a stable anionic semiquinone, beta-FAD-, which donates this electron further to Dh-FAD of BcdAf after a second domain movement. The remaining nonstabilized neutral semiquinone, alpha-FADH-, immediately reduces ferredoxin. Repetition of this process affords a second reduced ferredoxin and Dh-FADH- that converts crotonyl-CoA to butyryl-CoA | Acidaminococcus fermentans |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| crotonyl-CoA + 2 NADH + 2 Fd- | - |
Acidaminococcus fermentans | butyryl-CoA + 2 NAD+ + 2 Fd2- | - |
? | |
| crotonyl-CoA + 2 NADH + 2 Fd- | - |
Acidaminococcus fermentans VR4 | butyryl-CoA + 2 NAD+ + 2 Fd2- | - |
? | |
| crotonyl-CoA + reduced ferredoxin | - |
Acidaminococcus fermentans | butanoyl-CoA + oxidized ferredoxin | - |
? | |
| crotonyl-CoA + reduced ferredoxin | - |
Acidaminococcus fermentans ATCC 25085 | butanoyl-CoA + oxidized ferredoxin | - |
? | |
| additional information | the bifurcating electron transferring flavoprotein Etf and butanoyl-CoA dehydrogenase Bcd couple the exergonic reduction of crotonyl-CoA to butanoyl-CoA to the endergonic reduction of ferredoxin both with NADH. In the Etf-NADH complex, beta-FAD is acceptor of the hydride of NADH. The formed beta-FADH- is the bifurcating electron donor. As a result of a domain movement, alpha-FAD- takes up one electron yielding a stable anionic semiquinone, which donates this electron further to dehydrogenase-FAD of Bcd. The remaining nonstabilized neutral semiquinone, immediately reduces ferredoxin | Acidaminococcus fermentans | ? | - |
? | |
| additional information | the bifurcating electron transferring flavoprotein Etf and butanoyl-CoA dehydrogenase Bcd couple the exergonic reduction of crotonyl-CoA to butanoyl-CoA to the endergonic reduction of ferredoxin both with NADH. In the Etf-NADH complex, beta-FAD is acceptor of the hydride of NADH. The formed beta-FADH- is the bifurcating electron donor. As a result of a domain movement, alpha-FAD- takes up one electron yielding a stable anionic semiquinone, which donates this electron further to dehydrogenase-FAD of Bcd. The remaining nonstabilized neutral semiquinone, immediately reduces ferredoxin | Acidaminococcus fermentans ATCC 25085 | ? | - |
? | |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| Acfer_0556 | - |
Acidaminococcus fermentans |
| Acfer_1477 | - |
Acidaminococcus fermentans |
| BCD | - |
Acidaminococcus fermentans |
| BcdAf | - |
Acidaminococcus fermentans |
| non-dissociating bifurcating Etf-Bcd complex | - |
Acidaminococcus fermentans |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| FAD | EtfAf contains one FAD (alpha-FAD) in subunit alpha and a second FAD (beta-FAD) in subunit beta. The completely occupied, non-covalently bound alpha-FAD is present in a stretched conformation similar to that found in other Etf family members | Acidaminococcus fermentans | |
| Ferredoxin | - |
Acidaminococcus fermentans | |
| additional information | cofactors binding structure analysis, overview | Acidaminococcus fermentans | |
| NADH | - |
Acidaminococcus fermentans | |
General Information
| General Information | Comment | Organism |
|---|---|---|
| additional information | modeling of structures of the EtfAf-ferredoxin and EtfAf-BcdAf enzyme complexes | Acidaminococcus fermentans |
| physiological function | the bifurcating electron transferring flavoprotein (EtfAf) and butyryl-CoA dehydrogenase (BcdAf) of Acidaminococcus fermentans couples the exergonic reduction of crotonyl-CoA to butyryl-CoA to the endergonic reduction of ferredoxin both with NADH. NADH reduces beta-FAD of Etf, which bifurcates one electron reduces the Dh-FAD (dehydrogenase FAD) of butyryl-CoA dehydrogenase, and the other goes to ferredoxin characterized by a low redox potential. Repetition of this process leads to a second reduced ferredoxin and butyryl-CoA upon hydride transfer from FADH- of butyryl-CoA dehydrogenase to crotonyl-CoA | Acidaminococcus fermentans |
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