Difference between revisions of "Kroeger 1973 Eur J Biochem"
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{{Publication | {{Publication | ||
|title=Kröger 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 | |title=Kröger 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. | ||
|info=[https://pubmed.ncbi.nlm.nih.gov/4351161/ PMID:4351161 Open Access] | |info=[https://pubmed.ncbi.nlm.nih.gov/4351161/ PMID:4351161 Open Access] | ||
|authors=Kröger A, Klingenberg M | |authors=Kröger A, Klingenberg M | ||
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|abstract=The role of ubiquinone (Q) in the respiratory chain is quantitatively analyzed by correlating both the steadyâstate redox level of Q and the kinetics of oxidation and reduction with the flux of the overall electron transport in uncoupled submitochondrial particles. This is achieved by experimentally defining donor and acceptor activities for Q. | |abstract=The role of ubiquinone (Q) in the respiratory chain is quantitatively analyzed by correlating both the steadyâstate redox level of Q and the kinetics of oxidation and reduction with the flux of the overall electron transport in uncoupled submitochondrial particles. This is achieved by experimentally defining donor and acceptor activities for Q. | ||
1 | 1. The degree of reduction of Q in the steady state is proportional to the respiratory activity with NADH and succinate, if the respiratory activity is varied by titrating the donor side for Q with rotenone and malonate, respectively. The proportionality constant (acceptor activity, ''V''<sub>ox</sub>) is independent of the substrate used. | ||
The degree of reduction of Q in the steady state is proportional to the respiratory activity with NADH and succinate, if the respiratory activity is varied by titrating the donor side for Q with rotenone and malonate, respectively. The proportionality constant (acceptor activity, | |||
2 | 2. The degree of oxidation of Q in the steady state is proportional to the respiratory activity as varied by titration of the acceptor side for Q with antimycin. The proportionality constant (donor activity, ''V''<sub>red</sub>) is independent of the acceptor activity and depends on the dehydrogenase activity for NADH and succinate. | ||
The degree of oxidation of Q in the steady state is proportional to the respiratory activity as varied by titration of the acceptor side for Q with antimycin. The proportionality constant (donor activity, | |||
3 | 3. From these experimental relations, the redox state of Q in the steady state and the respiratory activity can be described as functions of the donor and the acceptor activity only. The equations are valid with both NADH and succinate as the substrates. | ||
From these experimental relations, the redox state of Q in the steady state and the respiratory activity can be described as functions of the donor and the acceptor activity only. The equations are valid with both NADH and succinate as the substrates. | |||
4 | 4. The kinetics of oxidation of Q on the addition of oxygen as measured by the quenchâflow method are in agreement with that measured by direct absorption recording in a mixing chamber. The reaction is first order with a rate constant equal to the acceptor activity divided by the amount of redoxâactive Q (''V''<sub>ox</sub>/Q<sub>a</sub>). The final steadyâstate level (in the present case 15 % reduction) is a result also of the reduction reaction with the firstâorder rate constant, ''V''<sub>redQa</sub>. | ||
The kinetics of oxidation of Q on the addition of oxygen as measured by the quenchâflow method are in agreement with that measured by direct absorption recording in a mixing chamber. The reaction is first order with a rate constant equal to the acceptor activity divided by the amount of redoxâactive Q ( | |||
5 | 5. The acceptor activity can also be measured as maximum respiratory activity with duroâhydroquinone. This activity is independent of the presence of Q but sensitive to antimycin. Thus, the acceptor activity for ubiquinone can be measured by three independent methods. | ||
The acceptor activity can also be measured as maximum respiratory activity with duroâhydroquinone. This activity is independent of the presence of Q but sensitive to antimycin. Thus, the acceptor activity for ubiquinone can be measured by three independent methods. | |||
6 | 6. It is concluded, that also in the steady state the reduction and oxidation of the active Qâpool follow pseudoâfirstâorder reactions, the rates of which are equal to the respiratory rate. The total amount of redoxâactive Q is kinetically and functionally homogeneous and is not divided into substrateâspecific compartments. | ||
It is concluded, that also in the steady state the reduction and oxidation of the active Qâpool follow pseudoâfirstâorder reactions, the rates of which are equal to the respiratory rate. The total amount of redoxâactive Q is kinetically and functionally homogeneous and is not divided into substrateâspecific compartments. | |||
|editor=Komlodi T | |editor=Komlodi T | ||
}} | }} | ||
== Cited by == | |||
{{Template:Cited by Komlodi 2021 MitoFit CoQ}} | |||
{{Labeling | {{Labeling | ||
|organism=Bovines | |||
|tissues=Heart | |||
|preparations=SMP | |||
|topics=Q-junction effect | |||
|additional=MitoFit 2021 CoQ | |additional=MitoFit 2021 CoQ | ||
}} | }} | ||
Latest revision as of 13:20, 3 April 2021
Kröger 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. |
Kröger A, Klingenberg M (1973) Eur J Biochem
Abstract: The role of ubiquinone (Q) in the respiratory chain is quantitatively analyzed by correlating both the steadyâstate redox level of Q and the kinetics of oxidation and reduction with the flux of the overall electron transport in uncoupled submitochondrial particles. This is achieved by experimentally defining donor and acceptor activities for Q.
1. The degree of reduction of Q in the steady state is proportional to the respiratory activity with NADH and succinate, if the respiratory activity is varied by titrating the donor side for Q with rotenone and malonate, respectively. The proportionality constant (acceptor activity, Vox) is independent of the substrate used.
2. The degree of oxidation of Q in the steady state is proportional to the respiratory activity as varied by titration of the acceptor side for Q with antimycin. The proportionality constant (donor activity, Vred) is independent of the acceptor activity and depends on the dehydrogenase activity for NADH and succinate.
3. From these experimental relations, the redox state of Q in the steady state and the respiratory activity can be described as functions of the donor and the acceptor activity only. The equations are valid with both NADH and succinate as the substrates.
4. The kinetics of oxidation of Q on the addition of oxygen as measured by the quenchâflow method are in agreement with that measured by direct absorption recording in a mixing chamber. The reaction is first order with a rate constant equal to the acceptor activity divided by the amount of redoxâactive Q (Vox/Qa). The final steadyâstate level (in the present case 15 % reduction) is a result also of the reduction reaction with the firstâorder rate constant, VredQa.
5. The acceptor activity can also be measured as maximum respiratory activity with duroâhydroquinone. This activity is independent of the presence of Q but sensitive to antimycin. Thus, the acceptor activity for ubiquinone can be measured by three independent methods.
6. It is concluded, that also in the steady state the reduction and oxidation of the active Qâpool follow pseudoâfirstâorder reactions, the rates of which are equal to the respiratory rate. The total amount of redoxâactive Q is kinetically and functionally homogeneous and is not divided into substrateâspecific compartments.
âą Bioblast editor: Komlodi T
Cited by
- KomlĂłdi 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
Labels:
Organism: Bovines
Tissue;cell: Heart
Preparation: SMP
Regulation: Q-junction effect
MitoFit 2021 CoQ