Description
The Q redox state reflects the redox status of the Q-junction in the mitochondrial or chloroplast electron transfer system (ETS). Ubiquinones, also known as coenzyme Q, and plastoquinones are essential mobile components of the mitochondria and chloroplasts that transfer electrons between the respiratory or photosynthetic complexes of the ETS. The Q redox state is dependent on the relative activities of the ETS enzymes that reduce and oxidize the quinones. Therefore, deficiencies in the mitochondrial ETS, originating from e.g. the malfunction of respiratory enzymes (complexes), can be detected by measuring the changes of the Q redox state with respect to respiratory activity.
Abbreviation: Qr/Qt
Calculation of the Q redox fractions
The Q redox state is expressed as the fraction of reduced Q (Qr) in each steady state of a SUIT protocol. In order to calculate the reduced Q fraction, the raw Q signal (Uraw) is calibrated against the fully oxidized Q signal (Uox) and the fully reduced Q signal (Ured). Uox is measured in the presence of CoQ2 and isolated mitochondria. The CI inhibitor rotenone might have to be added to inhibit respiration of endogenous substrates. Ured is determined under anoxia after the sample consumed the accessible O2 in the O2k-chamber. Qr is calculated as a proportion of the fully reduced Q. The sum of the oxidized and reduced fractions of Q equals 1, Qr+Qox = 1. In this formalism the intermediate redox state of semiquinone is not taken into account.
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 polarization voltage applied during Q-redox measurements.
- Reference:
- KomlΓ³di 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
- Reference:
Communicated by Komlodi T, Cardoso LHD (last update 2021-02-09)
- Bioblast links: Q - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>
- Coenzyme Q
- Β» Coenzyme Q
- Β» Quinone, Ubiquinone Q; oxidized
- Β» Quinol, Ubiquinol QH2; reduced
- Β» Semiquinone
- Β» Coenzyme Q2
- Β» Q-redox state
- Β» Q-pools
- Coenzyme Q
- Mitochondrial pathways, respiratory Complexes, and Q
- Β» Q-cycle
- Β» Q-junction
- Β» Convergent electron flow
- Β» NS-pathway
- Β» FNS
- Β» FNSGp
- Mitochondrial pathways, respiratory Complexes, and Q
- Β» N-pathway
- Β» Reverse electron flow from CII to CI
- Β» CI
- Β» Rotenone
- Β» Amytal
- Β» Piericidin
- NextGen-O2k and Q-Module
- Β» NextGen-O2k
- Β» Q-Module
- Β» Q-Sensor
- Β» Cyclic voltammetry
- Β» Three-electrode system
- NextGen-O2k and Q-Module
- General