Dynamics of redox potential and changes in redox state of iron and humic acids during gut passage in soil-feeding termites (Cubitermes spp.)

2002 ◽  
Vol 34 (2) ◽  
pp. 221-227 ◽  
Author(s):  
A Kappler
Keyword(s):  
Redox Potential ◽  
Humic Acids ◽  
Redox State ◽  
Gut Passage

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).

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

scholarly journals Titrations with ferrocyanide of japanese-lacquer-tree (Rhus vernicifera) laccase and of the type 2 copper-depleted enzyme. Interrelation of the copper sites

1980 ◽  
Vol 187 (2) ◽  
pp. 367-370 ◽  
Author(s):  
L Morpurgo ◽  
M T Graziani ◽  
A Desideri ◽  
G Rotilio
Keyword(s):  
Absorption Band ◽  
Redox Potential ◽  
Electron Acceptor ◽  
Redox State ◽  
Redox Potentials ◽  
Rhus Vernicifera ◽  
Type 3 ◽  
Limiting Value

1. Redox titrations are reported of the metal centres in Japanese-lacquer-tree (Rhus vernicifera) laccase with ferrocyanide. 2. The redox potential of Type 1 Cu was found to increase with ferrocyanide concentration up to a limiting value similar to that for the Type 1 Cu in Type 2 Cu-depleted enzyme (which is independent of ferrocyanide concentration). 3. The redox potential of the two-electron acceptor (Type 3 Cu) is also independent of ferrocyanide concentration in Type 2 Cu-depleted enzyme and lower than values reported for the native enzyme. 4. The two-electron acceptor is present in the oxidized state in the Type 2 Cu-depleted enzyme, though the latter lacks the 330 nm absorption band. 5. The redox potential of Type 2 Cu also depends on ferrocyanide concentration, at least in the presence of azide. 6. The redox potentials are affected by freezing the solutions and/or addition of azide, the latter binding to Type 2 Cu with affinity dependent on the redox state of the two-electron acceptor.

Effect of redox potential on protein degradation in perfused rat heart

1985 ◽  
Vol 248 (6) ◽  
pp. E726-E731
Author(s):  
B. H. Chua ◽  
B. J. Kleinhans
Keyword(s):  
Energy Source ◽  
Redox Potential ◽  
Protein Degradation ◽  
Rat Heart ◽  
Redox State ◽  
Inhibitory Effect ◽  
Experimental Conditions ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Sole Energy

The effect of redox potential on protein degradation was assessed in rat hearts supplied either glucose or pyruvate, and the correlation between redox state and proteolysis was examined after the addition of insulin and leucine. In hearts supplied glucose as the sole energy source, the inhibition of protein degradation by a range of concentrations of insulin was associated with increased ratios of perfusate lactate to pyruvate and intracellular lactate to pyruvate, malate to pyruvate, and NADH to NAD. However, the extent of inhibition did not correlate with the redox state. The inhibitory effect of leucine on protein degradation was not accompanied by any change in redox state of the hearts. In hearts provided with pyruvate, rates of protein degradation continued to be inhibited by insulin even though the perfusate lactate to pyruvate was decreased by 14-fold and the calculated cytosolic NADH-to-NAD ratios were only 3% of those seen in hearts supplied glucose. These results indicated that a correlation between redox state and protein degradation was not apparent in myocardium under the experimental conditions examined.

Acute nutrient regulation of the mitochondrial glutathione redox state in pancreatic β-cells

2014 ◽  
Vol 460 (3) ◽  
pp. 411-423 ◽  
Author(s):  
Hilton K. Takahashi ◽  
Laila R. B. Santos ◽  
Letícia P. Roma ◽  
Jessica Duprez ◽  
Christophe Broca ◽  
...  
Keyword(s):  
Redox Potential ◽  
Redox State ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Nutrient Regulation ◽  
Mitochondrial Glutathione ◽  
Glutathione Redox

Nutrient stimulation acutely reduces mitochondrial, but not cytosolic/nuclear, glutathione redox potential (EGSH) in insulin-secreting β-cells under control conditions. These changes are negatively correlated with NAD(P)H autofluorescence, but independent from changes in intracellular Ca2+ or mitochondrial pH.

Earth’s Electrodes

Elements ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 157-160 ◽  
Author(s):  
Maria Rita Cicconi ◽  
Roberto Moretti ◽  
Daniel R. Neuville
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Redox Potential ◽  
Oxygen Fugacity ◽  
Oxidation State ◽  
Redox State ◽  
Fluid Phase ◽  
Phase Relations ◽  
Geochemical Evolution ◽  
Oxidation Reduction

The oxidation–reduction (‘redox’) state is an important intensive property of any geologic system and is typically measured (and reported) as either the redox potential (Eh) or the oxygen fugacity (fO2). These two concepts cover the whole spectrum of geologic systems: from low-temperature aqueous and sedimentary systems to high-temperature rock-forming environments. The redox state determines the speciation of a fluid phase and exercises fundamental controls on phase relations and geochemical evolution. Here, we review the concepts that underpin the redox state and outline a framework for describing and quantifying the concept of the oxidation state.

scholarly journals Arteriovenous oscillations of the redox potential: Is the redox state influencing blood flow?

Redox Report ◽  
2016 ◽  
Vol 22 (5) ◽  
pp. 210-217
Author(s):  
Jaroslaw Poznanski ◽  
Pawel Szczesny ◽  
Bartosz Pawlinski ◽  
Tomasz Mazurek ◽  
Piotr Zielenkiewicz ◽  
...  
Keyword(s):  
Blood Flow ◽  
Redox Potential ◽  
Redox State

scholarly journals NADH/NAD redox state of cytoplasmic glycolytic compartments in vascular smooth muscle

2000 ◽  
Vol 279 (6) ◽  
pp. H2872-H2878 ◽  
Author(s):  
John T. Barron ◽  
Liping Gu ◽  
Joseph E. Parrillo
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Redox Potential ◽  
Redox State ◽  
Lactate Production ◽  
Glycolytic Flux ◽  
Dihydroxyacetone Phosphate ◽  
Redox Potentials ◽  
Redox Couples ◽  
Lactate And Pyruvate

The cytoplasmic NADH/NAD redox potential affects energy metabolism and contractile reactivity of vascular smooth muscle. NADH/NAD redox state in the cytosol is predominately determined by glycolysis, which in smooth muscle is separated into two functionally independent cytoplasmic compartments, one of which fuels the activity of Na+-K+-ATPase. We examined the effect of varying the glycolytic compartments on cystosolic NADH/NAD redox state. Inhibition of Na+-K+-ATPase by 10 μM ouabain resulted in decreased glycolysis and lactate production. Despite this, intracellular concentrations of the glycolytic metabolite redox couples of lactate/pyruvate and glycerol-3-phosphate/dihydroxyacetone phosphate (thus NADH/NAD) and the cytoplasmic redox state were unchanged. The constant concentration of the metabolite redox couples and redox potential was attributed to 1) decreased efflux of lactate and pyruvate due to decreased activity of monocarboxylate B-H+ transporter secondary to decreased availability of H+ for cotransport and 2) increased uptake of lactate (and perhaps pyruvate) from the extracellular space, probably mediated by the monocarboxylate-H+ transporter, which was specifically linked to reduced activity of Na+-K+-ATPase. We concluded that redox potentials of the two glycolytic compartments of the cytosol maintain equilibrium and that the cytoplasmic NADH/NAD redox potential remains constant in the steady state despite varying glycolytic flux in the cytosolic compartment for Na+-K+-ATPase.

The Effect of Chronic Consumption of Ethanol on the Redox State of the Rat Liver

1972 ◽  
Vol 50 (9) ◽  
pp. 949-957 ◽  
Author(s):  
Ellen R. Gordon
Keyword(s):  
Lactate Dehydrogenase ◽  
Redox Potential ◽  
Rat Liver ◽  
Redox State ◽  
Fatty Infiltration ◽  
Caloric Intake ◽  
Treated Group ◽  
Control Group ◽  
Control Groups ◽  
Nadh Ratio

Isocaloric replacement of the carbohydrate content of the diet by ethanol (36% of the total caloric intake) produced fatty infiltration and a reduced redox potential of the liver. The hepatic ratio of NAD+/NADH was 1.2 in the ethanol-treated group compared to 8.6 in the pair-fed control group. This change was associated with the consumption of ethanol as, 24 h after the removal of ethanol from the liver, the ratio had returned to the level of the control group. The hepatic substrate levels of NAD+-linked lactate dehydrogenase and the NAD+-linked β-hydroxybutyrate dehydrogenase systems were measured and used to calculate the NAD+/NADH ratio of the cytoplasm and mitochondria, respectively. The chronic consumption of ethanol did not alter the ratio in the cytoplasm but did shift the ratio in the mitochondria to one-fourth that observed in the control group. Twenty-four hours after ethanol was removed from the diet, this reduced redox potential in the mitochondria shifted to a level higher than that observed in the control groups.

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