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Gnaiger 2015 Abstract MiPschool Cape Town 2015 II
Coupling states LEAK  + , ROUTINE  + , OXPHOS  + , ET  +
Enzyme Supercomplex  +
Has abstract Electron transfer through respiratory enzy
Electron transfer through respiratory enzyme complexes is partially coupled to the phosphorylation of ADP to ATP by intermediary generation and utilization of the mt-membrane potential, Δ''p''<sub>mt</sub>. The electron transfer-pathway (ET-pathway) provides the driving input power with a chemical potential spanning from reduced electron donors (the fuel substrates) to the electron acceptor oxygen. At a theoretical maximum efficiency of 1.0, this input power would be fully backed off by a corresponding output power of proton translocation against a maximal output force Δ''p''<sub>mt</sub>, when fluxes would be reduced to zero in a fully coupled system. Maximal efficiency in the ADP-stimulated state of oxidative phosphorylation (OXPHOS) is, however, not adaptive [1] and is not observed in mitochondria for two reasons: (i) For fluxes to proceed and work to be done, output forces must be moderately high in relation to input forces, such that Gibbs energy is partially dissipated (mainly as heat in aerobic metabolism) and partially conserved as biochemical exergy [2]. (ii) Non-mechanical, incompletely coupled systems dissipate part of the potential energy in short-circuits (LEAK). Biochemical coupling is determined by measurement of respiratory fluxes in rigorously defined coupling states at constant ET-competent substrate states. [[File:P.jpg |link=OXPHOS capacity]] OXPHOS capacity, ''P'', is the respiratory capacity of mitochondria at saturating concentrations of ADP, inorganic phosphate, oxygen, and defined CHO fuel substrates. Intrinsic uncoupling and dyscoupling lower the efficiency and contribute to the control of flux in the OXPHOS state. ADP and inorganic phosphate do not equilibrate across the plasma membrane, and saturating concentrations of these metabolites can hardly be achieved in living cells. Therefore, cell membranes are permeabilized while maintaining mitochondria intact for the study of OXPHOS capacity, which provides a model for biochemical cell ergometry [3].
model for biochemical cell ergometry [3].  +
Has title On coupling control of mitochondrial respiration. What is wrong with the RCR?  +
MiP area Respiration  + , mt-Membrane  +
Pathways N  + , S  + , ROX  +
Was published by MiPNetLab AT Innsbruck Oroboros + , AT Innsbruck Gnaiger E +
Was submitted in year 2015  +
Was submitted to event MiPschool Cape Town 2015 +
Was written by Gnaiger E +
Categories Abstracts
Modification date
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09:04:27, 14 October 2018  +
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