Different Q-pools are more or less clearly distinguished in the cell, related to a variety of models describing degress of Q-pool behavior. (1) CoQ-pools are distinguished according to their compartmentation in the cell: mitochondrial CoQ (mtCoQ) and CoQ in other organelles versus plasma-membrane CoQ. (2) The total mitochondrial CoQ-pool mtCoQ is partitioned into an ETS-reactive Q-pool, Qra, and an inactive mtCoQ-pool, Qia. (2a) The Qra-pool is fully reduced in the form of quinol QH2 under anoxia, and fully oxidized in the form of quinone in aerobic mitochondrial preparations incubated without CHNO-fuel substrates. Intermediate redox states of Qra are sensitive to pathway control and coupling control of mitochondrial electron transfer and OXPHOS. (2b) The Qia-pool remains partially reduced and oxidized independent of aerobic-anoxic transitions. The redox state of Qia is insensitive to changes in mitochondrial respiratory states. (3) The Qra-pool is partitioned into Q with Q-pool behavior according to the fluid-state model (synonymous: random-collision model) and Q tightly bound to supercomplexes according to the solid-state model. The two models describe the extremes in a continuum of homogenous or heterogenous Q-pool behavior. The CII-Q-CIII segment of the S-pathway is frequently considered to follow homogenous Q-pool behavior participating in the Qhom-pool, whereas the CI-Q-CIII segment of the N-pathway indicates supercomplex organization and metabolic channeling with different degrees of Q-pool heterogeneity contributing to the Qhet-pool.
Reference: Komlodi 2021 MitoFit Q
Communicated by Gnaiger Erich 2021-04-03
|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 CHNO-fuel substrates||1, 2, 3|
|ETS-reactive Q||Qra = Q||electron-transfer-system reactive mtCoQ, fully reduced under anoxia, fully oxidized in aerobic mt-preparations incubated without CHNO-fuel substrates||Q = Qhom + Qhet||1, 2, 3|
|homogenous Q||Qhom||homogenous pool of ETS-reactive Q according to the fluid-state model (random-collision model)||1, 4, 5|
|heterogenous Q||Qhet||heterogenous pool of ETS-reactive Q according to the solid-state model||4-7|
- Kröger 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. - »Bioblast link«
- Jørgensen BM, Rasmussen HN, Rasmussen UF (1985) Ubiquinone reduction pattern in pigeon heart mitochondria. Identification of three distinct ubiquinone pools. Biochem J 229:621-9. - »Bioblast link« — A third Q-pool is suggested as an exo-mtCoQ-pool, detected by its reduction by added NADH and located on the outer face of the mtIM.
- Van 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. - »Bioblast link«
- Gutman 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. - »Bioblast link«
- Rich PR (1984) Electron and proton transfers through quinones and cytochrome bc complexes. Biochim Biophys Acta 768:53-79. - »Bioblast link«
- Lenaz 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. - »Bioblast link«
- Enriquez JA, Lenaz G (2014) Coenzyme Q and the respiratory chain: coenzyme Q pool and mitochondrial supercomplexes. Mol Syndromol 5:119-40. - »Bioblast link«
- Bioblast links: Q - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>
The Q-Module is part of the NextGen-O2k project
- The Q-Module allows for monitoring of the redox state of electron transfer-reactive coenzyme Q at the Q-junction using the specific Q-Stoppers with the integrated three-electrode system and the modified electronics of the NextGen-O2k. Cyclic voltammetry is used for quality control and for defining the polarisation voltage applied during Q-redox measurements.
- 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. https://doi.org/10.26124/bec:2021-0003
MitoPedia concepts: MiP concept
MitoPedia topics: Substrate and metabolite