Coenzyme Q

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high-resolution terminology - matching measurements at high-resolution

Coenzyme Q


Coenzyme Q or ubiquinone (2,3-dimethoxy-5-methyl-6-polyprenyl-1,4-benzoquinone) was discovered in 1957 by the group of Crane. It is a lipid composed of a benzoquinone ring with an isoprenoid side chain, two methoxy groups and one methyl group. The length of the isoprenoid chain varies depending on the species; for example, six isoprenoid units (CoQ6) is the most commonly found CoQ in Saccharomyces cerevisiae, eight units in Escherichia coli (CoQ8), nine units in Caenorhabditis elegans and rodents (CoQ9), ten units in humans (CoQ10), and some species have more than one CoQ form, e.g. human and rodent mitochondria contain different proportions of CoQ9 and CoQ10. These redox compounds exist in three different forms: quinone (oxidized), quinol (reduced), and an intermediate semiquinone.

More details » Q-junction

Abbreviation: Q, CoQ

Reference: Komlódi T, Cardoso LHD, Doerrier C, Moore AL, Rich PR, Gnaiger E (2021) Coupling and pathway control of coenzyme Q redox state and respiration in isolated mitochondria. Bioenerg Commun 2021.3.


Different forms are used to write coenzyme Q-10 in the literature: CoQ10 or CoQ10 or CoQ-10.
CoQ10 refers to all protonation states and the three redox states. It is useful to specify redox states by distinguishing CoQ10 (all species) from the oxidized ubiquinone-10 (UQ10), the reduced ubiquinol-10 (UQ10H2), and the free radical ubisemiquinone (USQ10•−). Song and Buettner (2011) use Q/SQ•−/H2Q for the quinone/semiquinone/hydroquinone triad. Whereas H2Q fits the term hydroquinone, the most commonly used term is (ubi)quinol with the corresponding acronyms QH2 and UQH2.
The redox states of plant plastoquinone-9 can be distinguished as PQ9 and PQ9H2. Hauvaux (2020) uses PQ-9 for the total pool of plastoquinone-9.
Name State Abbreviation Example
coenzyme Q all protonation and redox states CoQ CoQ10
ubiquinone oxidized UQ UQ10
ubiquinol reduced UQH2 UQ10H2
ubisemiquinone free radical USQ•− USQ10•−

Coenzyme Q pools

Q-pool Symbol Definition
coenzyme Q CoQ total CoQ in the cell, in mt-preparations, or added experimentally
mitochondrial CoQ mtCoQ total CoQ in mitochondria; mtCoQ = Qra + mtCoQia
inactive mtCoQ mtCoQia insensitive to changes in mitochondrial respiratory states; partially oxidized under anoxia and partially reduced in aerobic mt-preparations incubated without fuel substrates
ETS-reactive Q Qra ≝ Q fully reduced under anoxia, fully oxidized in aerobic mt-preparations incubated without external and internal fuel substrates and/or addition of inhibitors upstream of Q; Q = Qfree + QSC
free Q Qfree free pool of ETS-reactive Q according to the fluid-state model (random-collision model)
supercomplexed Q QSC pool of Qra bound to supercomplexes according to the solid-state model, not equilibrated with Qfree
Reference: Komlódi T, Cardoso LHD, Doerrier C, Moore AL, Rich PR, Gnaiger E (2021) Coupling and pathway control of coenzyme Q redox state and respiration in isolated mitochondria. Bioenerg Commun 2021.3.

Application in HRR

See: Coenzyme Q2

Keywords and references


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MitoPedia: mitObesity drugs


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AspirinAspirin is a widely applied drug that requires dosage adjusted to individual body mass. It is a non-selective COX inhibitor and exerts an effect on long-chain fatty acid transport into mitochondria.
CurcuminCurcumin has been shown to possess significant anti-inflammatory, anti-oxidant, anti-carcinogenic, anti-mutagenic, anti-coagulant and anti-infective effects. The protective effects of curcumin on rat heart mitochondrial injuries induced by in vitro anoxia–reoxygenation were evaluated by Xu et al 2013. It was found that curcumin added before anoxia or immediately prior to reoxygenation exhibited remarkable protective effects against anoxia–reoxygenation induced oxidative damage to mitochondria.
ElamipretideBendaviaBendavia (Elamipretide) was developed as a mitochondria-targeted drug against degenerative diseases, including cardiac ischemia-reperfusion injury. Clinical trials showed variable results. It is a cationic tetrapeptide which readily passes cell membranes, associates with cardiolipin in the mitochondrial inner membrane. Supercomplex-associated CIV activity significantly improved in response to elamipretide treatment in the failing human heart.
FlavonoidsFlavonoids are a group of bioactive polyphenols with potential antioxidant and anti-inflammatory effects, abundant in fruits and vegetables, and in some medicinal herbs. Flavonoids are synthesized in plants from phenylalanine. Dietary intake of flavonoids as nutraceuticals is discussed for targeting T2D and other degenerative diseases.
MelatoninaMTMelatonin (N-acetyl-5-methoxytryptamine, aMT) is a highly conserved molecule present in unicellular to vertebrate organisms. Melatonin is synthesized from tryptophan in the pinealocytes by the pineal gland and also is produced in other organs, tissues and fluids (extrapineal melatonin). Melatonin has lipophilic and hydrophilic nature which allows it to cross biological membranes. Therefore, melatonin is present in all subcellular compartments predominantly in the nucleus and mitochondria. Melatonin has pleiotropic functions with powerful antioxidant, anti-inflammatory and oncostatic effects with a wide spectrum of action particularly at the level of mitochondria. » MiPNet article
MetforminMetformin (dimethylbiguanide) is mainly known as an important antidiabetic drug which is effective, however, in a wide spectrum of degenerative diseases. It is an inhibitor of Complex I and glycerophosphate dehydrogenase complex.
RapamycinRapamycin is an inhibitor of the mammalian/mechanistic target of rapamycin, complex 1 (mTORC1). Rapamycin induces autophagy and dyscouples mitochondrial respiration. Rapamycin delays senescence in human cells, and extends lifespan in mice without detrimental effects on mitochondrial fitness in skeletal muscle.
ResveratrolResveratrol is a natural bioactive phenol prouced by several plants with antioxidant and anti-inflammatory effects. Dietary intake as nutraceutical is discussed for targeting mitochondria with a wide spectrum of action in degenerative diseases.
SpermidineSpermidine is a polycationic bioactive polyamine mainly found in wheat germ, soybean and various vegetables, involved in the regulation of mitophagy, cell growth and cell death. Like other caloric restriction mimetics, spermidine is effective in cardioprotection, neuroprotection and anticancer immunosuppression by preserving mitochondrial function and control of autophagy.
Healthy reference population     Body mass excess         BFE         BME cutoffs         BMI         H         M         VO2max         mitObesity drugs

Publications: Q-junction

Balmaceda 2024 Biochim Biophys Acta Mol Basis Dis2024Balmaceda V, Komlodi T, Szibor M, Gnaiger E, Moore AL, Fernandez-Vizarra E, Viscomi C (2024) The striking differences in the bioenergetics of brain and liver mitochondria are enhanced in mitochondrial disease. Biochim Biophys Acta Mol Basis Dis 1870:167033. system
Oxidative stress;RONS
Spielmann 2022 Mamm Genome2022Spielmann N, Schenkl C, Komlódi T, da Silva-Buttkus P, Heyne E, Rohde J, Amarie OV, Rathkolb B, Gnaiger E, Doenst T, Fuchs H, Gailus-Durner V, de Angelis MH, Szibor M (2022) Knockout of the Complex III subunit Uqcrh causes bioenergetic impairment and cardiac contractile dysfunction. Mamm Genome 10.1007/s00335-022-09973-wMouseHeartOxidative stress;RONS
Mitochondrial disease
Komlodi 2021 BEC Q2021Komlódi T, Cardoso LHD, Doerrier C, Moore AL, Rich PR, Gnaiger E (2021) Coupling and pathway control of coenzyme Q redox state and respiration in isolated mitochondria. Bioenerg Commun 2021.3.
Nervous system
Lemieux 2019 bioRxiv2019Lemieux H, Subarsky P, Doblander C, Wurm M, Troppmair J, Gnaiger E (2019) Mitochondrial respiratory function as an early biomarker of apoptosis induced by growth factor removal. bioRxiv doi: .MouseBlood cellsCell deathCancer
Osakai 2019 Electrochemistry2019Osakai T, Yamamoto T, Ueki M (2019) Directional electron transfer from ubiquinone-10 to cytochrome c at a biomimetic self-assembled monolayer modified electrode. Electrochemistry 87:59-64.
Takahashi 2019 Arch Biochem Biophys2019Takahashi T, Mine Y, Okamoto T (2019) Extracellular coenzyme Q10 (CoQ10) is reduced to ubiquinol-10 by intact Hep G2 cells independent of intracellular CoQ10 reduction. Arch Biochem Biophys 672:108067.
Spinazzi 2019 Proc Natl Acad Sci U S A2019Spinazzi M, Radaelli E, Horré K, Arranz AM, Gounko NV, Agostinis P, Maia TM, Impens F, Morais VA, Lopez-Lluch G, Serneels L, Navas P, De Strooper B (2019) PARL deficiency in mouse causes Complex III defects, coenzyme Q depletion, and Leigh-like syndrome. Proc Natl Acad Sci U S A 116:277-86. 10.1073/pnas.1811938116MouseNervous systemNeurodegenerative
Szibor 2019 Biochim Biophys Acta Bioenerg2019Szibor Marten, Gainutdinov Timur, Fernandez-Vizarra Erika, Dufour Eric, Gizatullina Zemfira, Debska-Vielhaber Grazyna, Heidler Juliana, Wittig Ilka, Viscomi Carlo, Gellerich Frank Norbert, Moore Anthony L (2019) Bioenergetic consequences from xenotopic expression of a tunicate AOX in mouse mitochondria: switch from RET and ROS to FET. Biochim Biophys Acta Bioenerg 1861:148137.MouseHeart
Cermakova 2019 Parasite2019Čermáková P, Kovalinka T, Ferenczyová K, Horváth A (2019) Coenzyme Q2 is a universal substrate for the measurement of respiratory chain enzyme activities in trypanosomatids. Parasite 26:17.
Martinez-Cifuentes 2017 Molecules2017Martínez-Cifuentes M, Salazar R, Ramírez-Rodríguez O, Weiss-López B, Araya-Maturana R (2017) Experimental and theoretical reduction potentials of some biologically active ortho-carbonyl para-quinones. Molecules 22:577.
Gulaboski 2016 J Solid State Electrochem2016Gulaboski R, Markovski V, Jihe Z (2016) Redox chemistry of coenzyme Q—a short overview of the voltammetric features. J Solid State Electrochem 20:3229–3238.
Fragaki 2016 Biol Res2016Fragaki K, Chaussenot A, Benoist JF, Ait-El-Mkadem S, Bannwarth S, Rouzier C, Cochaud C, Paquis-Flucklinger V (2016) Coenzyme Q10 defects may be associated with a deficiency of Q10-independent mitochondrial respiratory chain complexes. Biol Res 49:4.
Acosta 2016 Biochim Biophys Acta2016Acosta MJ, Vazquez Fonseca L, Desbats MA, Cerqua C, Zordan R, Trevisson E, Salviati L (2016) Coenzyme Q biosynthesis in health and disease. Biochim Biophys Acta 1857:1079-85.
García-Corzo 2015 Biochim Biophys Acta2015García-Corzo L, Luna-Sánchez M, Doerrier C, Ortiz F, Escames G, Acuña-Castroviejo D, López LC (2015) Ubiquinol-10 ameliorates mitochondrial encephalopathy associated with CoQ deficiency. Biochim Biophys Acta 1842:893-901.
Petrova 2014 Proc Chem2014Petrova EV, Korotkova EI, Kratochvil B, Voronova OA, Dorozhko EV, Bulycheva EV (2014) Investigation of coenzyme Q10 by voltammetry. Proc Chem 10:173-8.
Enriquez 2014 Mol Syndromol2014Enriquez JA, Lenaz G (2014) Coenzyme Q and the respiratory chain: coenzyme Q pool and mitochondrial supercomplexes. Mol Syndromol 5:119-40.Oxidative stress;RONS
La Guardia 2013 Front Physiol2013La Guardia PG, Alberici LC, Ravagnani FG, Catharino RR, Vercesi AE (2013) Protection of rat skeletal muscle fibers by either L-carnitine or coenzyme Q10 against statins toxicity mediated by mitochondrial reactive oxygen generation. Front Physiol 4:103.RatSkeletal muscleOxidative stress;RONS
Tang 2012 Methods Mol Biol2012Tang PH, Miles MV (2012) Measurement of oxidized and reduced coenzyme Q in biological fluids, cells, and tissues: an HPLC-EC method. Methods Mol Biol 837:149-68.
Song 2011 Free Radical Biol Med2011Song Y, Buettner GR (2011) Thermodynamic and kinetic considerations for the reaction of semiquinone radicals to form superoxide and hydrogen peroxide. Free Radical Biol Med 919-62.Oxidative stress;RONS
Albury 2009 Physiol Plant2009Albury MS, Elliott C, Moore AL (2009) Towards a structural elucidation of the alternative oxidase in plants. Physiol Plant 137:316-27.
Ausili 2008 J Phys Chem B2008Ausili A, Torrecillas A, Aranda F, de Godos A, Sánchez-Bautista S, Corbalán-García S, Gómez-Fernández JC (2008) Redox state of coenzyme Q10 determines its membrane localization. J Phys Chem B 112:12696-702.
Lenaz 2007 Am J Physiol Cell Physiol2007Lenaz G, Genova ML (2007) Kinetics of integrated electron transfer in the mitochondrial respiratory chain: random collisions vs. solid state electron channeling. Am J Physiol Cell Physiol 292:C1221-39. doi: 10.1152/ajpcell.00263.2006.
Michalkiewicz 2007 Bioelectrochemistry2007Michalkiewicz S (2007) Cathodic reduction of coenzyme Q10 on glassy carbon electrode in acetic acid-acetonitrile solutions. Bioelectrochemistry 70:495-500.
Pich 2002 Free Radic Res2002Pich MM, Castagnoli A, Biondi A, Bernacchia A, Tazzari PL, D'Aurelio M, Castelli GP, Formiggini G, Conte R, Bovina C, Lenaz G (2002) Ubiquinol and a coenzyme Q reducing system protect platelet mitochondrial function of transfusional buffy coats from oxidative stress. Free Radic Res 36:429-36.Blood cells
Oxidative stress;RONSAging;senescence
Affourtit 2001 J Biol Chem2001Affourtit C, Krab K, Leach GR, Whitehouse DG, Moore AL (2001) New insights into the regulation of plant succinate dehydrogenase. On the role of the protonmotive force. J Biol Chem 276:32567-74.
Cooley 2001 J Bacteriol2001Cooley JW, Vermaas WFJ (2001) Succinate Dehydrogenase and Other Respiratory Pathways in Thylakoid Membranes of Synechocystis sp. Strain PCC 6803: Capacity Comparisons and Physiological Function. J Bacteriol 183:4251-8.
Goetz 2000 J Neural Transm (Vienna)2000Götz ME, Gerstner A, Harth R, Dirr A, Janetzky B, Kuhn W, Riederer P, Gerlach M (2000) Altered redox state of platelet coenzyme Q10 in Parkinson's disease. J Neural Transm (Vienna) 107:41-8.
Affourtit 1999 J Biol Chem1999Affourtit C, Albury MS, Krab K, Moore AL (1999) Functional expression of the plant alternative oxidase affects growth of the yeast Schizosaccharomyces pombe. J Biol Chem 274:6212-8.
Wagner 1998 Plant Physiol1998Wagner AM, Wagner MJ, Moore AL (1998) In vivo ubiquinone reduction levels during thermogenesis in araceae. Plant Physiol 117:1501-6.
Rauchova 1995 Physiol Res1995Rauchová H, Drahota Z, Lenaz G (1995) Function of coenzyme Q in the cell: some biochemical and physiological properties. Physiol Res 44:209-16.
Meunier 1995 Biochemistry1995Meunier B, Madgwick SA, Reil E, Oettmeier W, Rich PR (1995) New inhibitors of the quinol oxidation sites of bacterial cytochromes bo and bd. Biochemistry 34:1076-83.
Van den Bergen 1994 Eur J Biochem1994Van den Bergen CW, Wagner AM, Krab K, Moore AL (1994) The relationship between electron flux and the redox poise of the quinone pool in plant mitochondria. Interplay between quinol-oxidizing and quinone-reducing pathways. Eur J Biochem 226:1071-8.
Moore 1991 Plant Physiol1991Moore AL, Dry IB, Wiskich JT (1991) Regulation of electron transport in plant mitochondria under state 4 conditions. Plant Physiol 95:34-40.
Day 1991 Plant Physiol1991Day DA, Dry IB, Soole KL, Wiskich JT, Moore AL (1991) Regulation of alternative pathway activity in plant mitochondria: deviations from Q-pool behavior during oxidation of NADH and quinols. Plant Physiol 95:948-53.
Zannoni 1990 FEBS Lett1990Zannoni D, Moore AL (1990) Measurement of the redox state of the ubiquinone pool in Rhodobacter capsulatus membrane fragments. FEBS Lett 271:123-7.
Dry 1989 Arch Biochem Biophys1989Dry IB, Moore AL, Day DA, Wiskich JT (1989) Regulation of alternative pathway activity in plant mitochondria: nonlinear relationship between electron flux and the redox poise of the quinone pool. Arch Biochem Biophys 273:148-57.
Moore 1988 FEBS Letters1988Moore AL, Dry IB, Wiskich TJ (1988) Measurement of the redox state of the ubiquinone pool in plant mitochondria. FEBS Lett 235:76-80.Plants
Ragan 1985 Biochim Biophys Acta1985Ragan CI, Cottingham IR (1985) The kinetics of quinone pools in electron transport. Biochim Biophys Acta 811:13-31.
Rich 1984 Biochim Biophys Acta1984Rich PR (1984) Electron and proton transfers through quinones and cytochrome bc complexes. Biochim Biophys Acta 768:53-79.
Mitchell 1979 Science1979Mitchell P (1979) Keilin’s respiratory chain concept and its chemiosmotic consequences. Science 206:1148-59.
Rich 1979 FEBS Lett1979Rich PR, Bendall DS (1979) A mechanism for the reduction of cytochromes by quinols in solution and its relevance to biological electron transfer reactions. FEBS Lett 105:189-94.
Mitchell 1975 FEBS Letters1975Mitchell P (1975) The protonmotive Q cycle: A general formulation. FEBS Lett 59:137-9.
Kroeger 1973 Eur J Biochem1973Kröger A, Klingenberg M (1973) The kinetics of the redox reactions of ubiquinone related to the electron-transport activity in the respiratory chain. Eur J Biochem 34:358-68.BovinesHeart
Kroeger 1973b Eur J Biochem1973Kröger A, Klingenberg M (1973) Further evidence for the pool function of ubiquinone as derived from the inhibition of the electron transport by antimycin. Eur J Biochem 39:313-23.BovinesHeart
Gutman 1972 FEBS Lett1972Gutman M, Silman N (1972) Mutual inhibition between NADH oxidase and succinoxidase activities in respiring submitochondrial particles. FEBS Lett 26:207-10. doi: 10.1016/0014-5793(72)80574-x.
Gutman 1971 Biochemistry1971Gutman M, Coles CJ, Singer TP, Casida JE (1971) On the functional organization of the respiratory chain at the dehydrogenase-coenzyme Q junction. Biochemistry 10:2036-43.
Ernster 1969 Eur J Biochem1969Ernster L, Lee IY, Norling B, Persson B (1969) Studies with ubiquinone-depleted submitochondrial particles. Essentiality of ubiquinone for the interaction of succinate dehydrogenase, NADH dehydrogenase, and cytochrome b. Eur J Biochem 9:299-310.BovinesHeart
Kroeger 1966 Biochem Z1966Kröger A, Klingenberg M (1966) On the role of ubiquinone in mitochondria. II. Redox reactions of ubiquinone under the control of oxidative phosphorylation. Biochem Z 344:317-36.BovinesHeart
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Abstracts: Q-junction
Ravasz 2019 Abstract IOC1412019Ravasz D, Bui D, Kitayev A, Greenwood B, Hill C, Komlodi T, Doerrier C, Ozohanics O, Moore AL, Gnaiger E, Kiebish M, Kolev K, Seyfried TN, Willis WT, Narain N, Adam-Vizi V, Chinopoulos C (2019) Endogenous quinones sustain a moderate NADH oxidation by Complex I during anoxia. Mitochondr Physiol Network 24.02.MouseLiver
Komlodi 2018 EBEC20182018Electron supply to the Q-junction: assessment of mitochondrial respiration, H2O2 flux and the redox state of the Q-pool.MouseNervous systemOxidative stress;RONS
Ravasz 2018 Abstract The evolving concept of mitochondria2018Vast pools of endogenous quinones sustain NADH oxidation by Complex I during anoxia, supporting substrate-level phosphorylation in mouse liver mitochondria.MouseLiverOther
Komlodi 2018 AussieMit2018Komlodi T, Hunger M, Moore AL, Gnaiger E (2018) Electron transfer at the Q-junction: new perspectives from combined measurement of mitochondrial O2 flux, H2O2 flux, and coenzyme Q redox state. AussieMit 2018 Melbourne AU.MouseNervous system
Komlodi 2018b EBEC20182018Endogenous quinones sustain NADH oxidation by Complex I during anoxia, supporting substrate-level phosphorylation in mouse liver mitochondria.MouseLiverPermeability transition
Oxidative stress;RONS
Komlodi 2017 MiPschool Obergurgl2017
Timea Komlodi
Electron pressure exerted by convergent succinate- and glycerophosphate-pathways to the Q-junction regulate reversed electron transfer to Complex I and H2O2 production.
MouseNervous systemOxidative stress;RONS
Moore 2017 MiPschool Obergurgl2017
Anthony Moore
The electron transfer-pathway – Q redox regulation and mitochondrial pathways to oxygen.

CoQ and mitObesity

Work in progress by Gnaiger E 2020-02-10 linked to a preprint in preparation on BME and mitObesity.
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