Effect of Redox Systems on Thermal Oxidative Plasticizing of Butadiene-Acrylonitrile Rubber

1960 ◽  
Vol 33 (3) ◽  
pp. 790-795
Author(s):  
E. Ya Devirts ◽  
A. S. Novikov
Keyword(s):  
Structure Formation ◽  
Redox System ◽  
Redox Systems ◽  
Iron Salts

Abstract 1. By using a redox system consisting of iron salts plus dimethylphenyl-paracresol, the rate of breakdown was considerably increased and structure-formation suppressed. This enables thermal oxidative plasticization to be used in industry for butadiene-acrylonitrile rubbers. 2. As the number of nitrile groups in the polymer increases, the rate of breakdown during thermal oxidative plasticization decreases and structure- formation occurs more rapidly. Butadiene-acrylonitrile (82:18) rubber has the greatest rate of breakdown, and the (60:40) copolymer the highest rate of structure-formation. 3. Vulcanizates of stocks based on thermally softened experimental butadiene-acrylonitrile rubbers are slightly inferior as regards strength and elasticity to similar vulcanizates of mechanically softened rubber. Their properties are, however, sufficiently high to enable thermal oxidative plasticization to be applied industrially.

scholarly journals Bacterial Periplasmic Oxidoreductases Control the Activity of Oxidized Human Antimicrobial β-Defensin 1

2018 ◽  
Vol 86 (4) ◽  
Author(s):  
J. Wendler ◽  
D. Ehmann ◽  
L. Courth ◽  
B. O. Schroeder ◽  
N. P. Malek ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Outer Membrane ◽  
Specific Activity ◽  
Redox System ◽  
Gram Negative Bacteria ◽  
Periplasmic Space ◽  
Redox Systems ◽  
Native Form ◽  
Gram Negative ◽  
Content Type

ABSTRACTThe antimicrobial peptide human β-defensin 1 (hBD1) is continuously produced by epithelial cells in many tissues. Compared to other defensins, hBD1 has only minor antibiotic activity in its native state. After reduction of its disulfide bridges, however, it becomes a potent antimicrobial agent against bacteria, while the oxidized native form (hBD1ox) shows specific activity against Gram-negative bacteria. We show that the killing mechanism of hBD1ox depends on aerobic growth conditions and bacterial enzymes. We analyzed the different activities of hBD1 using mutants ofEscherichia colilacking one or more specific proteins of their outer membrane, cytosol, or redox systems. We discovered that DsbA and DsbB are essential for the antimicrobial activity of hBD1ox but not for that of reduced hBD1 (hBD1red). Furthermore, our results strongly suggest that hBD1ox uses outer membrane protein FepA to penetrate the bacterial periplasm space. In contrast, other bacterial proteins in the outer membrane and cytosol did not modify the antimicrobial activity. Using immunogold labeling, we identified the localization of hBD1ox in the periplasmic space and partly in the outer membrane ofE. coli. However, in resistant mutants lacking DsbA and DsbB, hBD1ox was detected mainly in the bacterial cytosol. In summary, we discovered that hBD1ox could use FepA to enter the periplasmic space, where its activity depends on presence of DsbA and DsbB. HBD1ox concentrates in the periplasm in Gram-negative bacteria, which finally leads to bleb formation and death of the bacteria. Thus, the bacterial redox system plays an essential role in mechanisms of resistance against host-derived peptides such as hBD1.

scholarly journals Physicochemical and Analytical Implications of GATES/GEB Principles

2021 ◽  
Vol 2 (12) ◽  
pp. 1202-1210
Author(s):  
Anna M Michalowska-Kaczmarczyk ◽  
Tadeusz Michalowski
Keyword(s):  
Fundamental Property ◽  
Redox System ◽  
General Criterion ◽  
Charge Balance ◽  
Redox Systems ◽  
Oxidation Number ◽  
Electron Balance ◽  
Chemical Concepts ◽  
Equivalent Mass ◽  
Primary Form

The fundamental property of electrolytic systems involved with linear combination f12 = 2∙f(O) – f(H) of elemental balances: f1 = f(H) for Y1 = H, and f2 = f(O) for Y2 = O, is presented. The dependency/independency of the f12 on Charge Balance (f0 = ChB) and other elemental and/or core balances fk = f(Yk) (k = 3,…,K) is the general criterion distinguishing between non-redox and redox systems. The f12 related to a redox system is the primary form of a Generalized Electron Balance (GEB), formulated for redox systems within the Generalized Approach to Electrolytic System (GATES) as GATES/GEB ⊂ GATES. The set of K balances f0,f12,f3,…,fK is necessary/ sufficient/needed to solve an electrolytic redox system, while the K-1 balances f0,f3,…,fK are the set applied to solve an electrolytic non-redox system. The identity (0 = 0) procedure of checking the linear independency/ dependency property of f12 within the set f0,f12,f3,…,fK (i) provides the criterion distinguishing between the redox and non-redox systems and (ii) specifies Oxidation Numbers (ONs) of elements in particular components of the system, and in the species formed in the system. Some chemical concepts, such as oxidant, reductant, oxidation number, equivalent mass, stoichiometry, perceived as derivative within GATES, are indicated. All the information is gained on the basis of the titration Ce(SO4)2 (C) + H2SO4 (C1) + CO2 (C2) ⇨ FeSO4 (C0) + H2SO4 (C01) + CO2 (C02), simulated with use of the iterative computer program MATLAB.

scholarly journals RNA Viruses vs. DNA Synthesis: A General Viral Strategy That May Contribute to the Protective Antiviral Effects of Selenium

2020 ◽  
Author(s):  
Ethan Will Taylor
Keyword(s):  
Dna Synthesis ◽  
Rna Synthesis ◽  
Rna Viruses ◽  
Thioredoxin Reductase ◽  
Selenium Deficiency ◽  
Redox System ◽  
Redox Systems ◽  
Dna Viruses ◽  
Antisense Knockdown ◽  
Hiv 1

The biosynthesis of DNA inherently competes with RNA synthesis because it depends on the reduction of ribonucleotides (RNA precursors) to 2’-deoxyribonucleotides by ribonucleotide reductase (RNR). Hence, RNA viruses can increase viral RNA production in cells by partially blocking the synthesis of DNA, e.g. by downregulating the mammalian selenoprotein thioredoxin reductase (TR), which normally acts to sustain DNA synthesis by regenerating reduced thioredoxin, a hydrogen donor for RNR. Computational and preliminary experimental evidence supports the hypothesis that a number of pathogenic RNA viruses, including HIV-1, Ebola, Zika, some flu viruses, and SARS-CoV-2, target TR isoforms by antisense. TR knockdown would create a host antioxidant defect that could be partially rectified by increased selenium intake, or be exacerbated by selenium deficiency, contributing to viral pathogenesis. There are several non-selenium-dependent means that viruses might also exploit to slow DNA synthesis, such as targeting RNR itself, or components of the glutaredoxin system, which serves as a backup redox system for RNR. HIV-1 substantially downregulates glutathione synthesis, so it interferes with both the thioredoxin and glutaredoxin systems. Computational results suggest that, like Ebola, SARS-CoV-2 targets TR3 by antisense. TR3 is the only TR isoform that includes an N-terminal glutaredoxin domain, so antisense knockdown of TR3 may also affect both redox systems, favoring RNA synthesis. In contrast, some DNA viruses encode their own glutaredoxins, thioredoxin-like proteins and even RNR homologues – so they are doing just the opposite, favoring DNA synthesis. This is clear evidence that viruses can benefit from shifting the RNA:DNA balance to their advantage.

scholarly journals Some Regularities Inherent in the Balance 2∙f(O) – f(H) Formulated for an Electrolytic System with Symproportionation Reactions Involved

2021 ◽  
pp. 1-11
Author(s):  
Anna Maria Michałowska-Kaczmarczyk ◽  
Tadeusz Michałowski
Keyword(s):  
Linear Combination ◽  
Linear Dependence ◽  
Redox System ◽  
General Criterion ◽  
Redox Systems ◽  
General Properties ◽  
Electron Balance ◽  
Equivalent Mass ◽  
Primary Form

The general properties of the balance f12 = 2∙f(O) – f(H), as the linear combination of elemental balances: f1 = f(H) for H and f2 = f(O) for O, formulated for electrolytic systems, are presented. These properties/regularities are inherently related to linear combination (LC) of f12 with charge (f0) and other elemental/core balances fk = f(Yk) (Yk ≠ H, O), expressed by, where the multipliers dk are involved with oxidation numbers (ONs) of the elements in the system in question. The linear dependence or independence of f12 from f0,f3,…, fK, expressed by LC, provides the general criterion distinguishing between non-redox and redox systems. The f12 is the primary form of Generalized electron balance (GEB), completing the set of K independent balances f0,f12,f3,…,fK needed for the solution of a redox system according to GATES/GEB principles. For the solution of a non-redox system, the set of K–1 independent equations f0,f3,…,fK is required. In this formulation, the terms: ONs, oxidant, reductant, and equivalent mass are derivative/redundant concepts. These properties/regularities of f12 are illustrated here by a redox system where symproportionation reactions occur.

scholarly journals Human pancreatic cancer cells under nutrient deprivation are vulnerable to redox system inhibition

2020 ◽  
Vol 295 (49) ◽  
pp. 16678-16690
Author(s):  
Takefumi Onodera ◽  
Isao Momose ◽  
Hayamitsu Adachi ◽  
Yohko Yamazaki ◽  
Ryuichi Sawa ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cancer Cells ◽  
High Throughput Screening ◽  
Sufficient Conditions ◽  
Redox System ◽  
Vascular Supply ◽  
Human Pancreatic Cancer ◽  
Microbial Culture ◽  
Redox Systems ◽  
Pancreatic Cancer Cells

Large regions in tumor tissues, particularly pancreatic cancer, are hypoxic and nutrient-deprived because of unregulated cell growth and insufficient vascular supply. Certain cancer cells, such as those inside a tumor, can tolerate these severe conditions and survive for prolonged periods. We hypothesized that small molecular agents, which can preferentially reduce cancer cell survival under nutrient-deprived conditions, could function as anticancer drugs. In this study, we constructed a high-throughput screening system to identify such small molecules and screened chemical libraries and microbial culture extracts. We were able to determine that some small molecular compounds, such as penicillic acid, papyracillic acid, and auranofin, exhibit preferential cytotoxicity to human pancreatic cancer cells under nutrient-deprived compared with nutrient-sufficient conditions. Further analysis revealed that these compounds target to redox systems such as GSH and thioredoxin and induce accumulation of reactive oxygen species in nutrient-deprived cancer cells, potentially contributing to apoptosis under nutrient-deprived conditions. Nutrient-deficient cancer cells are often deficient in GSH; thus, they are susceptible to redox system inhibitors. Targeting redox systems might be an attractive therapeutic strategy under nutrient-deprived conditions of the tumor microenvironment.

scholarly journals Melatonin maintains the function of the blood redox system at combined ethanol-induced toxicity and subclinical inflammation in mice

2020 ◽  
Author(s):  
Natalia Kurhaluk ◽  
Halyna Tkachenko ◽  
Oleksandr Lukash ◽  
Pawel J. Winklewski ◽  
Magdalena Wszedybyl-Winklewska
Keyword(s):  
Oxidative Stress ◽  
Free Radical Oxidation ◽  
Redox System ◽  
Erythrocyte Membranes ◽  
Redox Systems ◽  
Negative Effects ◽  
Melatonin Treatment ◽  
Radical Oxidation ◽  
Acute Ethanol ◽  
High Level

Abstract Background The goal of this study was to assess the effect of melatonin on blood redox systems in mice simultaneously exposed to ethanol and low-dose lipopolysaccharide (LPS). Methods Oxidative stress parameters were assessed in eight groups: untreated control, melatonin (10 mg kg−1, 10 days), LPS (injected once intraperitoneally at a dose of 150 μg per mouse), LPS with previous melatonin treatment, acute ethanol-induced stress (AES, 0.75 g kg−1 per day, 10 days), AES with previous melatonin treatment, LPS- and AES-induced toxicity, and melatonin treatment. Results Both ethanol and LPS induced oxidative stress. The combination of these two factors was even more toxic to the organism. Melatonin stabilized erythrocyte membranes and decreased the high level of free radical oxidation at the initial and final stages. Furthermore, melatonin limited protein damage through maintenance in the functional ability of the blood redox system to counteract pathological conditions. Conclusions Melatonin limited the negative effects associated with alcohol consumption and low-intensity inflammation.

scholarly journals Insights into the function of NADPH thioredoxin reductase C (NTRC) based on identification of NTRC-interacting proteins in vivo

2019 ◽  
Vol 70 (20) ◽  
pp. 5787-5798 ◽  
Author(s):  
Maricruz González ◽  
Víctor Delgado-Requerey ◽  
Julia Ferrández ◽  
Antonio Serna ◽  
Francisco Javier Cejudo
Keyword(s):  
Redox Regulation ◽  
Fluorescent Protein ◽  
Affinity Purification ◽  
Photosynthetic Apparatus ◽  
Thioredoxin Reductase ◽  
Redox System ◽  
Negative Control ◽  
Bimolecular Fluorescence Complementation ◽  
Redox Systems

Abstract Redox regulation in heterotrophic organisms relies on NADPH, thioredoxins (TRXs), and an NADPH-dependent TRX reductase (NTR). In contrast, chloroplasts harbor two redox systems, one that uses photoreduced ferredoxin (Fd), an Fd-dependent TRX reductase (FTR), and TRXs, which links redox regulation to light, and NTRC, which allows the use of NADPH for redox regulation. It has been shown that NTRC-dependent regulation of 2-Cys peroxiredoxin (PRX) is critical for optimal function of the photosynthetic apparatus. Thus, the objective of the present study was the analysis of the interaction of NTRC and 2-Cys PRX in vivo and the identification of proteins interacting with them with the aim of identifying chloroplast processes regulated by this redox system. To assess this objective, we generated Arabidopsis thaliana plants expressing either an NTRC–tandem affinity purification (TAP)-Tag or a green fluorescent protein (GFP)–TAP-Tag, which served as a negative control. The presence of 2-Cys PRX and NTRC in complexes isolated from NTRC–TAP-Tag-expressing plants confirmed the interaction of these proteins in vivo. The identification of proteins co-purified in these complexes by MS revealed the relevance of the NTRC–2-Cys PRX system in the redox regulation of multiple chloroplast processes. The interaction of NTRC with selected targets was confirmed in vivo by bimolecular fluorescence complementation (BiFC) assays.

scholarly journals Redox Systems in Botrytis cinerea: Impact on Development and Virulence

2014 ◽  
Vol 27 (8) ◽  
pp. 858-874 ◽  
Author(s):  
Anne Viefhues ◽  
Jens Heller ◽  
Nora Temme ◽  
Paul Tudzynski
Keyword(s):  
Botrytis Cinerea ◽  
Redox Homeostasis ◽  
Thioredoxin Reductase ◽  
Redox System ◽  
Redox Status ◽  
Redox Systems ◽  
Gene Encoding ◽  
Cellular Redox ◽  
Thioredoxin System ◽  
The Impact

The thioredoxin system is of great importance for maintenance of cellular redox homeostasis. Here, we show that it has a severe influence on virulence of Botrytis cinerea, demonstrating that redox processes are important for host-pathogen interactions in this necrotrophic plant pathogen. The thioredoxin system is composed of two enzymes, the thioredoxin and the thioredoxin reductase. We identified two genes encoding for thioredoxins (bctrx1, bctrx2) and one gene encoding for a thioredoxin reductase (bctrr1) in the genome of B. cinerea. Knockout mutants of bctrx1 and bctrr1 were severely impaired in virulence and more sensitive to oxidative stress. Additionally, Δbctrr1 showed enhanced H2O2 production and retarded growth. To investigate the impact of the second major cellular redox system, glutathione, we generated deletion mutants for two glutathione reductase genes. The effects were only marginal; deletion of bcglr1 resulted in reduced germination and, correspondingly, to retarded infection as well as reduced growth on minimal medium, whereas bcglr2 deletion had no distinctive phenotype. In summary, we showed that the balanced redox status maintained by the thioredoxin system is essential for development and pathogenesis of B. cinerea, whereas the second major cellular redox system, the glutathione system, seems to have only minor impact on these processes.

scholarly journals The Balance 2∙f (O) – f (H) as a Cornerstone in Formulation of Electrolytic Systems

2018 ◽  
Vol 2 (1) ◽  
pp. 1-13
Author(s):  
Anna M. Michałowska-Kaczmarczyk ◽  
Tadeusz Michałowski
Keyword(s):  
Linear Combination ◽  
Redox System ◽  
Card Game ◽  
Redox Systems ◽  
Common Pool ◽  
Active Elements ◽  
Electron Balance ◽  
The Common

The Generalized Electron Balance (GEB) concept, related to electrolytic redox systems, is considered according to principles of Generalized Approach to Electrolytic Systems (GATES). Two equivalent Approaches (I and II) to GEB are presented. The Approach I, when perceived in convention of the card game, is based on the common pool of electrons as money, introduced by electron-active elements, named as players; electron-non-active elements are called there as fans. The GEB obtained according to Approach II results from the linear combination f12 = 2∙f(O) – f(H) of elemental balances: f1 = f(H) for H, and f2 = f(O) for O. Very important properties of f12 are presented here in details, and illustrated by a redox system where comproportion- ation reactions occur

The Effects of the Herbicide Sethoxydim on Transport Processes in Sensitive and Tolerant Grass Species II. Effects on Membrane-Bound Redox Systems in Plant Cells

1988 ◽  
Vol 43 (3-4) ◽  
pp. 257-263 ◽  
Author(s):  
Angela Weber ◽  
Ulrich Lüttge
Keyword(s):  
Electron Transport ◽  
Poa Pratensis ◽  
Redox System ◽  
Transport Processes ◽  
Grass Species ◽  
Sensitive Species ◽  
Redox Systems ◽  
Ferricyanide Reduction ◽  
Membrane Bound ◽  
Photometric Measurements

Leaf slices of sethoxydim-sensitive (Poa pratensis, Festuca ovina) and tolerant (Poa annua, Festuca rubra) grass species were found to be able to reduce extracellular ferricyanide by electron transport across the plasmalemma. This reduction was inhibited by the herbicide sethoxydim, and the sensitive species were much more strongly affected than the tolerant ones. The inhibition was concentration dependent. Sethoxydim affected the electron transport in isolated Poo chloroplasts. Polarographic and photometric measurements of ferricyanide reduction suggested photosystem II to be the site of action. Inhibition occurred only in the sensitive species Poa pratensis and was linearly dependent on concentration. In isolated mitochondria from sensitive Zea mays coleoptiles sethoxydim also acted as an inhibitor of electron transport. Only slight inhibition was measured with mitochondria from tubers of tolerant potato (Solanum tuberosum). It is concluded that sethoxydim generally acts as inhibitor of membrane-bound redox systems. The specific inhibition of the plasmalemma-bound redox system of sethoxydim-sensitive plants could contribute to a selective action of the herbicide.

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