Electron-transferring-flavoprotein dehydrogenase

Electron-transferring-flavoprotein dehydrogenase
Ribbon diagram of electron-transferring-flavoprotein dehydrogenase with each functional domain differentially colored. Blue band is membrane area.
Identifiers
Symbol	ETFD
Alt. symbols	ETF-QO
Entrez	2110
HUGO	3483
OMIM	231675
PDB	2GMH
RefSeq	NM_004453
UniProt	Q16134
Other data
EC number	1.5.5.1
Locus	Chr. 4 q4q32.1

Electron-transferring-flavoprotein dehydrogenase (ETF dehydrogenase or electron transfer flavoprotein-ubiquinone oxidoreductase, EC 1.5.5.1) is an enzyme that transfers electrons from electron-transferring flavoprotein in the , to the ubiquinone pool in the . It is part of the electron transport chain. The enzyme is found in both prokaryotes and eukaryotes and contains a flavin and FE-S cluster. In humans, it is encoded by the ETFDH gene. Deficiency in ETF dehydrogenase causes the human genetic disease multiple acyl-CoA dehydrogenase deficiency.

ETQ-QO links the oxidation of fatty acids and some amino acids to oxidative phosphorylation in the mitochondria. Specifically, it catalyzes the transfer of electrons from electron transferring flavoprotein (ETF) to ubiquinone, reducing it to ubiquinol. The entire sequence of transfer reactions is as follows:

Acyl-CoA → Acyl-CoA dehydrogenase → ETF → ETF-QO → UQ → Complex III.

The overall reaction catalyzed by ETF-QO is as follows:

ETF-QO(red) + ubiquinone ↔ ETF-QO(ox) + ubiquinol

Enzymatic activity is usually assayed spectrophotometrically by reaction with octanoyl-CoA as the electron donor and ubiquinone-1 as the electron acceptor. The enzyme can also be assayed via disproportionation of ETF semiquinone. Both reactions are below: