Effect of membrane conductance on proton/electron stoichiometry of cytochrome c oxidase activity in plant mitochondria

Virville, Jacques Davy de; Moreau, F.

doi:10.1016/0005-2728(90)90080-n

Cited by 1 publication

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“…Wikström and co‐workers were the first to demonstrate proton pumping activity of cytochrome c oxidase,33a, 33b but for a long time the ratio between translocated protons and transported electrons (H + /e − stoichiometry) remained controversial. In fact, H + /e − ratios between zero,34a, 34b 1.0,35a–35d and 2.036a–36f were determined. After numerous discussions it was generally accepted that the H + /e − ratio in cytochrome c oxidases of bacteria37 and mitochondria38 invariably is 1.0 39a.…”

Section: Proton Pathways In Cytochrome C Oxidasementioning

confidence: 99%

Cytochrome c Oxidase and the Regulation of Oxidative Phosphorylation

et al. 2001

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Life of higher organisms is essentially dependent on the efficient synthesis of ATP by oxidative phosphorylation in mitochondria. An important and as yet unsolved question of energy metabolism is how are the variable rates of ATP synthesis at maximal work load during exercise or mental work and at rest or during sleep regulated. This article reviews our present knowledge on the structure of bacterial and eukaryotic cytochrome c oxidases and correlates it with recent results on the regulatory functions of nuclear-coded subunits of the eukaryotic enzyme, which are absent from the bacterial enzyme. A new molecular hypothesis on the physiological regulation of oxidative phosphorylation is proposed, assuming a hormonally controlled dynamic equilibrium in vivo between two states of energy metabolism, a relaxed state with low ROS (reactive oxygen species) formation, and an excited state with elevated formation of ROS, which are known to accelerate aging and to cause degenerative diseases and cancer. The hypothesis is based on the allosteric ATP inhibition of cytochrome c oxidase at high intramitochondrial ATP/ADP ratios ("second mechanism of respiratory control"), which is switched on by cAMP-dependent phosphorylation and switched off by calcium-induced dephosphorylation of the enzyme.

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