scholarly journals Average oxidation state of carbon in proteins

2014 ◽  
Author(s):  
Jeffrey M. Dick
Keyword(s):  
Redox Potential ◽  
Oxidation State ◽  
Optimal Growth ◽  
Extracellular Proteins ◽  
Biochemical Processes ◽  
Average Oxidation State ◽  
Oxidation Reduction ◽  
Chemical Conditions ◽  
Thermophilic Organisms ◽  
Glutathione Redox

The degree of oxidation of carbon atoms in organic molecules depends on the covalent structure. In proteins, the average oxidation state of carbon (ZC) can be calculated as an elemental ratio from the chemical formula. To investigate oxidation-reduction (redox) patterns, groups of proteins from different subcellular locations and phylogenetic divisions were selected for comparison. Extracellular proteins of yeast have a relatively high oxidation state of carbon, corresponding with oxidizing conditions outside of the cell. However, an inverse relationship betweenZCand redox potential occurs between the endoplasmic reticulum and cytoplasm; this trend is interpreted as resulting from overall coupling of protein turnover to the formation of a lower glutathione redox potential in the cytoplasm. In Rubisco homologues, lowerZCtends to occur in organisms with higher optimal growth temperature, and there are broad changes inZCin whole-genome protein compositions in microbes from different environments. Energetic costs calculated from thermodynamic models suggest that thermophilic organisms exhibit molecular adaptation to not only high temperature but also the reducing nature of many hydrothermal fluids. A view of protein metabolism that depends on the chemical conditions of cells and environments raises new questions linking biochemical processes to changes on evolutionary timescales.

scholarly journals Average oxidation state of carbon in proteins

2014 ◽  
Vol 11 (100) ◽  
pp. 20131095 ◽  
Author(s):  
Jeffrey M. Dick
Keyword(s):  
Oxidation State ◽  
Protein Transport ◽  
Optimal Growth ◽  
Extracellular Proteins ◽  
Redox Potentials ◽  
Phylogenetic Groups ◽  
Average Oxidation State ◽  
Oxidation Reduction ◽  
Chemical Conditions ◽  
Thermophilic Organisms

The formal oxidation state of carbon atoms in organic molecules depends on the covalent structure. In proteins, the average oxidation state of carbon ( Z C ) can be calculated as an elemental ratio from the chemical formula. To investigate oxidation–reduction (redox) patterns, groups of proteins from different subcellular locations and phylogenetic groups were selected for comparison. Extracellular proteins of yeast have a relatively high oxidation state of carbon, corresponding with oxidizing conditions outside of the cell. However, an inverse relationship between Z C and redox potential occurs between the endoplasmic reticulum and cytoplasm. This trend provides support for the hypothesis that protein transport and turnover are ultimately coupled to the maintenance of different glutathione redox potentials in subcellular compartments. There are broad changes in Z C in whole-genome protein compositions in microbes from different environments, and in Rubisco homologues, lower Z C tends to occur in organisms with higher optimal growth temperature. Energetic costs calculated from thermodynamic models are consistent with the notion that thermophilic organisms exhibit molecular adaptation to not only high temperature but also the reducing nature of many hydrothermal fluids. Further characterization of the material requirements of protein metabolism in terms of the chemical conditions of cells and environments may help to reveal other linkages among biochemical processes with implications for changes on evolutionary time scales.

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 Tumor cell anti-oxidant defenses. Inhibition of the glutathione redox cycle enhances macrophage-mediated cytolysis

1981 ◽  
Vol 153 (4) ◽  
pp. 766-782 ◽  
Author(s):  
CF Nathan ◽  
BA Arrick ◽  
HW Murray ◽  
NM DeSantis ◽  
ZA Cohm
Keyword(s):  
Tumor Cell ◽  
Tumor Cells ◽  
Defense Mechanisms ◽  
Specific Activity ◽  
Protective Role ◽  
Target Cells ◽  
Redox Cycle ◽  
Oxidation Reduction ◽  
Glutathione Redox Cycle ◽  
Glutathione Redox

The basis of resistance to oxidative injury was studied in six murine tumor cell lines that differed 54-fold in their resistance to enzymatically generated H(2)0(2). The tumors varied 56.7-fold in their specific activity of catalase, 5.3-fold in glutathione peroxidase (GPO), 3.3-fold in glutathione reductase (GR), and 2.7-fold in glutathione. There was no correlation among the levels of the three enzymes, and tumor cell resistance to lysis by H(2)0(2). However, the logarithm of the flux of H(2)0(2) necessary to cause 50 percent lysis of the tumor cells correlated with their content of glutathione (r = 0.91). The protective role of glutathione was analyzed by blocking GR and GPO, the catalysts of the glutathione redox cycle. This was facilitated by the demonstration that the anti-neoplastic agent 1,3-bis-(2- chloroethyl)-l-nitrosourea (BCNU) was a potent inhibitor of GR in intact tumor cells. BCNU inactivated tumor cell GR with a 50 percent inhibitory dose of 11 μM and a t(l/2) of inhibition of 30 s. Complete inhibition of GR was attained with no effect on GPO or catalase. Tumor cells whose GR was inactivated by BCNU could be lysed by fluxes of H(2)0(2) to which they were otherwise completely resistant. They could be killed by phorbol myristate acetate (PMA)-stimulated, bacilli Calmette-Guerin-activated macrophages in numbers which were otherwise insufficient, and by nonactivated macrophages, which otherwise were ineffective. BCNU-treated target cells were also much more sensitive to antibody-dependent, macrophage-mediated cytolysis. However, such tumor cells were no more sensitive than controls to lysis by alloreactive T cells or by antibody plus complement. Next, we deprived tumor cells of selenium by passage in selenium-deficient mice. GPO was inhibited 85 percent in such cells, with no effect on GR or catalase. Tumor cells with reduced GPO activity were markedly sensitized to lysis by small fluxes of H(2)0(2) or by PMA-stimulated macrophages or granulocytes. In contrast, inhibition of catalase with aminotriazole had no effect on the sensitivity of three tumors to peroxide-mediated lysis, and had modest effects with two others. Thus, the oxidation-reduction cycle of glutathione serves as one of the major defense mechanisms of tumor cells against three related forms of oxidant injury: lysis by fluxes of H(2)0(2), by PMA-triggered macrophages, and by macrophages in the presence of anti-tumor antibody.

scholarly journals Glutathione redox potential is low and glutathionylated and cysteinylated hemoglobin levels are elevated in maintenance hemodialysis patients

2013 ◽  
Vol 162 (1) ◽  
pp. 16-25 ◽  
Author(s):  
Khaled Khazim ◽  
Daniela Giustarini ◽  
Ranieri Rossi ◽  
Darlene Verkaik ◽  
John E. Cornell ◽  
...  
Keyword(s):  
Redox Potential ◽  
Hemodialysis Patients ◽  
Maintenance Hemodialysis ◽  
Glutathione Redox ◽  
Maintenance Hemodialysis Patients

scholarly journals Tunable Mn Oxidation State and Redox Potential of Birnessite Coexisting with Aqueous Mn(II) in Mildly Acidic Environments

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 690
Author(s):  
Juan Liu ◽  
Yixiao Zhang ◽  
Qian Gu ◽  
Anxu Sheng ◽  
Baogang Zhang
Keyword(s):  
Oxidation State ◽  
Organic Pollutant ◽  
Equilibrium Concentration ◽  
Aquatic Environments ◽  
Oxidation Potentials ◽  
Average Oxidation State ◽  
Subsurface Environments ◽  
Equilibrium Concentrations ◽  
Kinetics Of ◽  
Manganese Oxide Mineral

As the dominant manganese oxide mineral phase in terrestrial and aquatic environments, birnessite plays an important role in many biogeochemical processes. The coexistence of birnessite with aqueous Mn2+ is commonly found in the subsurface environments undergoing Mn redox cycling. This study investigates the change in Mn average oxidation state (AOS) of birnessite after reaction with 0.1–0.4 mM Mn2+ at pH 4.5–6.5, under conditions in which phase transformation of birnessite by Mn2+ was not detectable. The amount of Mn2+ uptake by birnessite and the equilibrium concentration of Mn(III) proportionally increased with the initial concentration of Mn2+. The Mn AOS of birnessite particles became 3.87, 3.75, 3.64, and 3.53, respectively, after reaction with 0.1, 0.2, 0.3, and 0.4 mM Mn2+ at pH 5.5. Oxidation potentials (Eh) of birnessite with different AOS values were estimated using the equilibrium concentrations of hydroquinone oxidized by the birnessite samples, indicating that Eh was linearly proportional to AOS. The oxidation kinetics of bisphenol A (BPA), a model organic pollutant, by birnessite suggest that the logarithms of surface area-normalized pseudo-first-order initial rate constants (log kSA) for BPA degradation by birnessite were linearly correlated with the Eh or AOS values of birnessite with AOS greater than 3.64.

Confocal imaging of glutathione redox potential in living plant cells

2008 ◽  
Vol 231 (2) ◽  
pp. 299-316 ◽  
Author(s):  
M. SCHWARZLÄNDER ◽  
M.D. FRICKER ◽  
C. MÜLLER ◽  
L. MARTY ◽  
T. BRACH ◽  
...  
Keyword(s):  
Redox Potential ◽  
Plant Cells ◽  
Confocal Imaging ◽  
Living Plant ◽  
Glutathione Redox

The glutathione degrading enzyme, Chac1, is required for calcium signaling in developing zebrafish: redox as an upstream activator of calcium

2019 ◽  
Vol 476 (13) ◽  
pp. 1857-1873 ◽  
Author(s):  
Shambhu Yadav ◽  
Bindia Chawla ◽  
Mohammad Anwar Khursheed ◽  
Rajesh Ramachandran ◽  
Anand Kumar Bachhawat
Keyword(s):  
Redox Potential ◽  
Calcium Signaling ◽  
Reduced Glutathione ◽  
Developmental Defects ◽  
Degrading Enzyme ◽  
Embryonic Lethal ◽  
Intracellular Glutathione ◽  
Cellular Oxidation ◽  
Glutathione Redox

Abstract Calcium signaling is essential for embryonic development but the signals upstream of calcium are only partially understood. Here, we investigate the role of the intracellular glutathione redox potential in calcium signaling using the Chac1 protein of zebrafish. A member of the γ-glutamylcyclotransferase family of enzymes, the zebrafish Chac1 is a glutathione-degrading enzyme that acts only on reduced glutathione. The zebrafish chac1 expression was seen early in development, and in the latter stages, in the developing muscles, brain and heart. The chac1 knockdown was embryonic lethal, and the developmental defects were seen primarily in the myotome, brain and heart where chac1 was maximally expressed. The phenotypes could be rescued by the WT Chac1 but not by the catalytically inactive Chac1 that was incapable of degrading glutathione. The ability of chac1 to alter the intracellular glutathione redox potential in the live animals was examined using Grx1-roGFP2. The chac1 morphants lacked the increased degree of cellular oxidation seen in the WT zebrafish. As calcium is also known to be critical for the developing myotomes, brain and heart, we further investigated if the chac1 knockdown phenotypes were a consequence of the lack of calcium signals. We observed using GCaMP6s, that calcium transients normally seen in the developing embryos were strongly attenuated in these knockdowns. The study thus identifies Chac1 and the consequent change in intracellular glutathione redox potential as important upstream activators of calcium signaling during development.

Ti4O7 Used as Electrode in Biomedicine and for Electrochemical Study of Scavenging Mechanism

2011 ◽  
Vol 493-494 ◽  
pp. 896-901
Author(s):  
María Canillas ◽  
Ann Rajnicek ◽  
C. Rosero ◽  
Eva Chinarro ◽  
Berta Moreno
Keyword(s):  
Oxidation State ◽  
Reactive Species ◽  
Electrochemical Methods ◽  
Electrochemical Study ◽  
Scavenging Activity ◽  
Reduction Reactions ◽  
Oxidation Reduction ◽  
Nitrogen Reactive Species

The biocompatibility of TiO2 is due to the activity that it shown in front of oxygen and nitrogen reactive species. Some authors suggest that the mechanism go through oxidation reduction reactions where changes of oxidation state in the Titanium and phases are involve. For this reason, Anderson-Magnelli phases could present scavenging activity. Moreover, these materials are use as electrodes and in that way are proposed as electrodes for study their scavenging mechanism by electrochemical methods.

Real-time imaging of the intracellular glutathione redox potential

2008 ◽  
Vol 5 (6) ◽  
pp. 553-559 ◽  
Author(s):  
Marcus Gutscher ◽  
Anne-Laure Pauleau ◽  
Laurent Marty ◽  
Thorsten Brach ◽  
Guido H Wabnitz ◽  
...  
Keyword(s):  
Redox Potential ◽  
Real Time ◽  
Real Time Imaging ◽  
Intracellular Glutathione ◽  
Glutathione Redox

Control of oxidation-reduction potential during Cheddar cheese ripening and its effect on the production of volatile flavour compounds

2016 ◽  
Vol 83 (4) ◽  
pp. 479-486 ◽  
Author(s):  
Veronica Caldeo ◽  
John A Hannon ◽  
Dara-Kate Hickey ◽  
Dave Waldron ◽  
Martin G Wilkinson ◽  
...  
Keyword(s):  
Redox Potential ◽  
Cheddar Cheese ◽  
Principal Component ◽  
Reducing Agents ◽  
Sulphur Compounds ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Volatile Flavour ◽  
Redox Agents ◽  
The Stability

In cheese, a negative oxidation-reduction (redox) potential is required for the stability of aroma, especially that associated with volatile sulphur compounds. To control the redox potential during ripening, redox agents were added to the salted curd of Cheddar cheese before pressing. The control cheese contained only salt, while different oxidising or reducing agents were added with the NaCl to the experimental cheeses. KIO3 (at 0·05, 0·1 and 1%, w/w) was used as the oxidising agent while cysteine (at 2%, w/w) and Na2S2O4 (at 0·05 and 0·1%, w/w) were used as reducing agents. During ripening the redox potential of the cheeses made with the reducing agents did not differ significantly from the control cheese (Eh ≈ −120 mV) while the cheeses made with 0·1 and 0·05% KIO3 had a significantly higher and positive redox potential in the first month of ripening. Cheese made with 1% KIO3 had positive values of redox potential throughout ripening but no starter lactic acid bacteria survived in this cheese; however, numbers of starter organisms in all other cheeses were similar. Principal component analysis (PCA) of the volatile compounds clearly separated the cheeses made with the reducing agents from cheeses made with the oxidising agents at 2 month of ripening. Cheeses with reducing agents were characterized by the presence of sulphur compounds whereas cheeses made with KIO3 were characterized mainly by aldehydes. At 6 month of ripening, separation by PCA was less evident. These findings support the hypothesis that redox potential could be controlled during ripening and that this parameter has an influence on the development of cheese flavour.

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