Electron-transferring flavoprotein and

Toogood HS, Leys D, Scrutton NS. Dynamics driving function new insights from electron transferring flavoproteins and partner complexes. FEBS J. 2007 274 5481-5504. 

Frerman FE, Goodman SI. Defects of the electron transfer flavoprotein and electron transfer flavopro-tein-ubiquinone oxidoreductase glutaric acidemia type II. In Scriver CR, Beaudet AL, Valle D, Sly WS, Childs B, Kinzler KW, et al, eds. The metabofic molecular bases of inherited disease, 8th ed. New York McGraw-Hill, 2001 2357-65. 

Hall C.L. Kamin H. (1975) The purification and some properties of electron transfer flavoprotein and general acyl-CoA dehydrogenase from pig liver mitochondria. J Biol Chem 250 3476-86. 

Figure 37.2 Cartoon depicting enzymes participating in mitochondrial P-oxidation and part of the respiratory chain. Acyl-CoA substrates derived from fatty acid and amino acid metabolism are oxidized by several flavin-containing acyl-CoA dehydrogenases (ACAD). Electrons obtained from this reaction are shuttled to the respiratory chain via the ETF/ETF QO hub (electron-transfer flavoprotein and electron-transfer flavoprotein ubiquinone oxidoreductase). ETF QO is able to transfer electrons to ubiquinone (Q) (such as respiratory complexes I and II) whose subsequent transfer down to complex IV will result in energy conservation and ATP production. See list of abbreviations for definitions.

Nagao, M., and Tanaka, K., 1992. FAD-dependent regulation of transcription, translation, post-translational processing, and post-processing stability of various mitochondrial acyl-CoA dehydrogenases and of electron transfer flavoprotein and the site of holoenzyme formation. The Journal of Biological Chemistry. 267 17925-17932. 

Ma, Y.C., Funk, M., Dunham, W.R. and Komuniecki, R. (1993) Purification and characterization of electron-transfer flavoprotein rhodoquinone oxidoreduc-tase from anaerobic mitochondria of anaerobic mitochondria of the adult parasitic nematode, Ascaris suum. Journal of Biological Chemistry 268, 20360-20365. 

Glutaric acidurias Type I Primary defect of glutarate oxidation Type II Defect of electron transfer flavoprotein Type I Severe basal ganglia/cerebellar disease with macrocephaly. Onset 1-2 years Type II Fulminant neurological syndrome of the neonate. Often with renal/hepatic cysts. Usually fatal Diet low in lysine and tryptophan Supplementation with coenzyme Q, riboflavin, carnitine... 

This enzyme [EC 1.3.99.13] catalyzes the reaction of a long-chain acyl-CoA with an electron-transferring fla-voprotein to produce a 2,3-dehydroacyl-CoA and the reduced electron-transferring flavoprotein. 

The oxidation of fatty acids is catalyzed by the FAD-containing acyl coenzyme A dehydrogenases which transfer reducing equivalents to the mitochondrial respiratory chain via a flavin-containing electron transfer flavoprotein (ETF) and subsequently via an ETF dehydrogenase (an Fe/S flavoprotein In addition to the mammalian... 

Fig. 5.2. Possible metabolic pathways in facultative anaerobic mitochondria. Shaded boxes show components of the electron-transport chain used during hypoxia, open boxes are components used during aerobiosis, and the hatched boxes (complex I and ATP-synthase) are components used under aerobic as well as anaerobic conditions. ASCT acetate succinate CoA-transferase, C cytochrome c, Cl, CIII and CIV complexes I, III and IV of the respiratory chain, CITR citrate, ECR enoyl-CoA reductase (such as present in Ascaris suum), ETF electron-transfer flavoprotein, ETF RQ OR electron-transfer flavoproteimrhodoquinone oxidoreductase, FRD fumarate reductase, FUM fumarate, MAE malate, OXAC oxaloacetate, PYR pyruvate, RQ rhodoquinone, SDH succinate dehydrogenase, SUCC succinate, Succ-CoA succinyl-CoA, TER trans-2-enoyl-CoA reductase (such as present in E. gracilis), UQ ubiquinone...

As described before, also the formation of branched-chain fatty acids by enoyl-CoA reductase activity is coupled to electron transport (Komuniecki and Harris 1995). In this case electrons are transported from NADH to rhodoquinone via complex I and subsequently to the electron-transfer flavoprotein (ETF) via ETF-reductase (Fig. 5.3). The soluble, non-membrane-bound ETF then transfers electrons to enoyl-CoA reductase, which uses the electrons for the condensation of two short-chain (C2-C3) acyl-CoA moieties for the formation of branched-chain fatty acids. 

Komuniecki R, McCrury J, Thissen J, Rubin N (1989) Electron-transfer flavoprotein from anaerobic Ascaris suum mitochondria and its role in NADH-dependent 2-methyl branched-chain enoyl-CoA reduction. Biochim Biophys Acta 975 127-131 Komuniecki R, Harris BG (1995) Carbohydrate and energy metabolism in helminths. In Marr JJ, Muller M (eds) Biochemistry and molecular biology of parasites. Academic, London, pp 49-66... 

Figure 18.5 The glycerol-3-phosphate shuttle. This shuttle is used to bring electrons from cytosolic NADH into mitochondria. The mitochondrial glycerol-3-phosphate dehydrogenase with its FAD prosthetic group is bound to the inner mitochondrial membrane. ETF is electron transfer flavoprotein, which extracts electrons from the FADH2 of mitochondrial glycerol-3-phosphate dehydrogenase and with it reduces ubiquinone (UQ).

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