scholarly journals THe proton-per-electron stoicheiometry of ‘site 1’ of oxidative phosphorylation at high protonmotive force is close to 1.5

1982 ◽  
Vol 204 (2) ◽  
pp. 515-523 ◽  
Author(s):  
P C de Jonge ◽  
H V Westerhoff
Keyword(s):  
Redox Potential ◽  
Redox State ◽  
Dynamic Equilibrium ◽  
Experimental Situation ◽  
Potential Difference ◽  
Protonmotive Force ◽  
Submitochondrial Particles ◽  
Output Force ◽  
Group Translocation ◽  
Static Head

The maximum redox potential difference between the NAD+/NADH couple and the succinate/fumarate couple generated during ATP-energized reduction of NAD+ by succinate in submitochondrial particles was measured, together with the electrochemical potential difference for protons (delta mu approximately H+). The presence of cyanide, the time-independence of the redox potential difference and the irrelevance of the initial redox state of the NAD+/NADH couple ensured that the experimental situation corresponded to a ‘static-head condition’ with delta mu approximately H+ as the input force and the redox potential difference as the output force, the flow of electrons having reached dynamic equilibrium. Consequently, the observed value of 1.6 for the ratio delta Ge/delta mu approximately H+ is interpreted as indicating that the leads to H+/e- stoicheiometry at ‘site 1’ is 1.5 and that therefore the mechanism of the proton pump at ‘site 1’ is not of the group-translocation type (no direct leads to e - leads to H+ coupling).

The effect of the protonmotive force on the redox state of mitochondrial cytochromes

1994 ◽  
Vol 1187 (2) ◽  
pp. 140-144 ◽  
Author(s):  
Giovanni F. Azzone ◽  
Ibolya Schmehl ◽  
Marcella Canton ◽  
Siro Luvisetto
Keyword(s):  
Redox State ◽  
Protonmotive Force ◽  
Mitochondrial Cytochromes

Cellular redox state protects acetaldehyde-induced alteration in cardiomyocyte function by modifying Ca2+ release from sarcoplasmic reticulum

2008 ◽  
Vol 294 (1) ◽  
pp. H121-H133 ◽  
Author(s):  
Toshiharu Oba ◽  
Yoshitaka Maeno ◽  
Masataka Nagao ◽  
Nagahiko Sakuma ◽  
Takashi Murayama
Keyword(s):  
Redox Potential ◽  
Redox State ◽  
Ventricular Myocytes ◽  
Imaging System ◽  
Reduced Glutathione ◽  
Confocal Imaging ◽  
Minor Effect ◽  
Channel Activity ◽  
Ryr2 Channel ◽  
Cardiac Excitation

Recent studies indicate that low concentrations of acetaldehyde may function as the primary factor in alcoholic cardiomyopathy by disrupting Ca2+ handling or disturbing cardiac excitation-contraction coupling. By producing reactive oxygen species, acetaldehyde shifts the intracellular redox potential from a reduced state to an oxidized state. We examined whether the redox state modulates acetaldehyde-induced Ca2+ handling by measuring Ca2+ transient using a confocal imaging system and single ryanodine receptor type 2 (RyR2) channel activity using the planar lipid bilayer method. Ca2+ transient was recorded in isolated rat ventricular myocytes with incorporated fluo 3. Intracellular reduced glutathione level was estimated using the monochlorobimane fluorometric method. Acetaldehyde at 1 and 10 μM increased Ca2+ transient amplitude and its relative area in intact myocytes, but acetaldehyde at 100 μM decreased Ca2+ transient area significantly. Acetaldehyde showed a minor effect on Ca2+ transient in myocytes in which intracellular reduced glutathione content had been decreased against challenge of diethylmaleate to a level comparable to that induced by exposure to ∼50 μM acetaldehyde. Channel activity of the RyR2 with slightly reduced cytoplasmic redox potential from near resting state (−213 mV) or without redox fixation was augmented by all concentrations of acetaldehyde (1–100 μM) used here. However, acetaldehyde failed to activate the RyR2 channel, when the cytoplasmic redox potential was kept with a reduced (−230 mV) or markedly oxidized (−180 mV) state. This result was similar to effects of acetaldehyde on Ca2+ transient in diethylmaleate-treated myocytes, probably being in oxidized redox potential. The present results suggest that acetaldehyde acts as an RyR2 activator to disturb cardiac muscle function, and redox potential protects the heart from acetaldehyde-induced alterations in myocytes.

scholarly journals Glutathione redox potential in the mitochondrial intermembrane space is linked to the cytosol and impacts the Mia40 redox state

2012 ◽  
Vol 31 (14) ◽  
pp. 3169-3182 ◽  
Author(s):  
Kerstin Kojer ◽  
Melanie Bien ◽  
Heike Gangel ◽  
Bruce Morgan ◽  
Tobias P Dick ◽  
...  
Keyword(s):  
Redox Potential ◽  
Redox State ◽  
Intermembrane Space ◽  
Mitochondrial Intermembrane Space ◽  
Glutathione Redox

Characterization of In-Core Water Chemistry for Corrosion Control of LWRs

2014 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Redox Potential ◽  
Water Chemistry ◽  
Single Point ◽  
Experimental Results ◽  
Potential Difference ◽  
Corrosion Mechanism ◽  
Recent Theory ◽  
Scientific Validity ◽  
Pile Test ◽  
Test Loop

This paper updates scientific bases of water chemistry in applying the author’s recent theory, which integrates the elemental radiation- and electro-chemistry reactions in the “Butlar-Volmer equation,” presented in ICONE21-16525. For the past several years the author has been trying to establish that the “long-cell” (a kin to macro-cell) corrosion mechanism is inducing practically all sorts of accelerated corrosion phenomena widely observed in water-cooled reactors, especially in aged plants. The theoretical electrochemical potential differences have been benchmarked with the published in-pile test results for both PWR- and BWR water chemistry environments. However the author’s previous verification efforts were limited to the extent that the curves were fitted with experimental results at a single point. The author re-formulated the basic theory and found that the redox potential difference consists of an electrochemical part (e.g., Nernst equation of dissolved hydrogen or oxygen) and radiation-induced perturbation term, the latter diminishes to zero without radiation. The author continued his studies to clarify whether our current scientific knowledge is sufficient to explain the in-core “chemistry” to reproduce the experimental results without the fitting parameter. Through his study he realized that the basic mechanism of the potential difference is still not sufficiently known. No fitting parameter was used for the PWR water chemistry in the DH region for practical engineering applications, although it is indispensable to confirm the results with an in-pile test loop. In the BWR-NWC the theoretical redox potential out of core was still necessary to be fitted with the experimental results, due to an effect of residual hydrogen peroxide detected by the reference electrode. In addition the calculated potential shift is several times larger than the experimental observation. With the reformulation the scientific validity of the author’s theory is further confirmed. He believes that there is no doubt that the “long-cell” takes place in LWRs, although details are still debatable.

Syntheses, characterization and electrochemical and spectroscopic properties of ruthenium–iron complexes of 2,3,5,6-tetrakis(2-pyridyl)pyrazine and ferrocene-acetylide ligands

2016 ◽  
Vol 45 (26) ◽  
pp. 10620-10629 ◽  
Author(s):  
Hui-Min Wen ◽  
Jin-Yun Wang ◽  
Li-Yi Zhang ◽  
Lin-Xi Shi ◽  
Zhong-Ning Chen
Keyword(s):  
Redox Potential ◽  
Mixed Valence ◽  
Iron Complexes ◽  
Spectroscopic Properties ◽  
Potential Difference

A mixed-valence RuIIFeIII complex displays 0.50 V of redox potential difference induced by Ru⋯Fe interactions across the Ru–CC–Fc backbone and moderate IVCT band centered at 1247 nm.

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