scholarly journals Respiration-driven proton translocation by yeast mitochondria with differing efficiencies of oxidative phosphorylation

1973 ◽  
Vol 134 (4) ◽  
pp. 1045-1049 ◽  
Author(s):  
J. A. Downie ◽  
P. B. Garland
Keyword(s):  
Oxidative Phosphorylation ◽  
Energy Conservation ◽  
Candida Utilis ◽  
Proton Translocation ◽  
Yeast Mitochondria

Measurements were made of the stoicheiometry of proton translocation coupled to respiration in mitochondria from Candida utilis where the number of functional energy-conservation sites between intramitochondrial NADH and oxygen was one in a mutant with a novel oxidase (Downie & Garland, 1972), two in sulphate-deficient cells (Haddock & Garland, 1971) or three in glycerol-limited cells (Light & Garland, 1971). The stoicheiometries of protons translocated per atom of oxygen utilized (i.e. →H+/2e− ratio; Mitchell, 1966) were close to 2.0, 4.0 and 6.0 respectively. Thus by using the same substrate (intramitochondrial NADH) and oxygen throughout, the →H+/2e− ratio is shown to be 2.0 per energy-conservation site when the number of such sites is varied from one to three.

Oxidative phosphorylation and respiratory control in mitochondria from Aspergillus oryzae

1969 ◽  
Vol 15 (8) ◽  
pp. 975-977 ◽  
Author(s):  
K. Watson ◽  
W. Paton ◽  
J. E. Smith
Keyword(s):  
Bovine Serum Albumin ◽  
Oxidative Phosphorylation ◽  
Aspergillus Oryzae ◽  
Reaction Medium ◽  
Respiratory Control ◽  
Adenosine Diphosphate ◽  
Yeast Mitochondria ◽  
Active Oxidation ◽  
Isolated Mitochondria ◽  
Ph Range

Mitochondria isolated from Aspergillus oryzae exhibited respiratory control with a range of substrates. Bovine serum albumin was required in the reaction medium to observe adenosine diphosphate (ADP) controlled respiration. The mitochondria carried out active oxidation and phosphorylation with citrate as substrate in the pH range 6–7 and showed a slight optimum for oxidative phosphorylation at pH 6.5. The respiratory properties of the isolated mitochondria were similar to those reported for A. niger and yeast mitochondria.

scholarly journals Chemiosmotic coupling in oxidative phosphorylation: The history of a hard experimental effort hampered by the Heisenberg indeterminacy principle

2018 ◽  
Author(s):  
Alessandro Maria Morelli ◽  
Silvia Ravera ◽  
Daniela Calzia ◽  
Isabella Panfoli
Keyword(s):  
Oxidative Phosphorylation ◽  
Proton Translocation ◽  
Structural Data ◽  
Biological Research ◽  
Proton Pumps ◽  
Chemiosmotic Theory ◽  
Respiratory Chain Complexes ◽  
Chain Complexes ◽  
Definition Of ◽  
Chemiosmotic Coupling

Understanding how biological systems convert and store energy is a primary goal of biological research. However, despite the formulation of Mitchell’s chemiosmotic theory, which allowed taking fundamental steps forward, we are still far from the complete decryption of basic processes as oxidative phosphorylation (OXPHOS) and photosynthesis. After more than half a century, the chemiosmotic theory appears to need updating, as some of its assumptions have proven incorrect in the light of the latest structural data on respiratory chain complexes, bacteriorhodopsin and proton pumps. Moreover, the existence of an OXPHOS on the plasma membrane of cells casts doubt on the possibility to build up a transversal proton gradient across it, while paving the way for important applications in the field of neurochemistry and oncology. Up-to date biotechnologies, such as fluorescence indicators can follow proton displacement and sinks, and a number of reports have elegantly demonstrated that proton translocation is lateral rather than transversal with respect to the coupling membrane. Furthermore, the definition of the physical species involved in the transfer (proton, hydroxonium ion or proton currents) is still unresolved even though the latest acquisitions support the idea that protonic currents, difficult to measure, are involved. It seems that the concept of diffusion of the proton expressed more than two centuries ago by Theodor von Grotthuss, is decisive for overcoming these issues. All these uncertainties remember us that also in biology it is necessary to take into account the Heisenberg indeterminacy principle, that sets limits to analytical questions.

Artificial Energy Conservation in Bacterial Photosynthetic Electron Transport

1976 ◽  
Vol 31 (3-4) ◽  
pp. 152-156 ◽  
Author(s):  
Achim Trebst
Keyword(s):  
Electron Transport ◽  
Energy Conservation ◽  
Proton Pump ◽  
Redox Reaction ◽  
Electron Flow ◽  
Proton Translocation ◽  
Photosynthetic Electron Transport ◽  
Reaction Cycle ◽  
Atp Formation ◽  
Internal Electron

Abstract In photosynthesis of chloroplasts and bacterial chromatophores an induced artificial electron flow bypass may restore the inhibition of electron flow and of coupled ATP formation by two possible mechanisms. An artificial transmembrane electron flow bypass will lead to artificial energy conservation, when the redox reaction cycle of the added mediator across the membrane acts as proton pump. In an artificial internal electron flow bypass an inhibited native energy conservation may be reactivated; here an electron flow bypass induced by the mediator in the inside space restores the native proton translocation. The inhibition and the restoration of electron flow by antimycin, dibromothymoquinone and valinomycin is compared.

SITES OF ENERGY CONSERVATION IN OXIDATIVE PHOSPHORYLATION

1957 ◽  
Vol 79 (11) ◽  
pp. 2970-2970 ◽  
Author(s):  
Britton Chance ◽  
Gunnar Hollunger
Keyword(s):  
Oxidative Phosphorylation ◽  
Energy Conservation
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