redox buffers
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Mitochondria (mt) represent the vital hub of the molecular physiology of the cell, being decision-makers in cell life/death and information signaling, including major redox regulations and redox signaling. Now we review recent advances in understanding mitochondrial redox homeostasis, including superoxide sources and H2O2 consumers, i.e., antioxidant mechanisms, as well as exemplar situations of physiological redox signaling, including the intramitochondrial one and mt-to-cytosol redox signals, which may be classified as acute and long-term signals. This review exemplifies the acute redox signals in hypoxic cell adaptation and upon insulin secretion in pancreatic beta-cells. We also show how metabolic changes under these circumstances are linked to mitochondrial cristae narrowing at higher intensity of ATP synthesis. Also, we will discuss major redox buffers, namely the peroxiredoxin system, which may also promote redox signaling. We will point out that pathological thresholds exist, specific for each cell type, above which the superoxide sources exceed regular antioxidant capacity and the concomitant harmful processes of oxidative stress subsequently initiate etiology of numerous diseases. The redox signaling may be impaired when sunk in such excessive pro-oxidative state.
The present paper is focused on zinc(ii) treatment effects on prostatic cell lines PC-3 (tumour) and PNT1A (non-tumour). Oxidative status of cells was monitored by evaluation of expression of metallothionein (MT) isoforms 1A and 2A at the mRNA and protein level, glutathione (oxidised and reduced), and intracellular zinc(ii) after exposition to zinc(ii) treatment at concentrations of 0-150 μM using electrochemical methods, western blotting and fluorescent microscopy. A novel real-time impedance-based growth monitoring system was compared with widely used end-point MTT assay. Impedance-based IC(50) for zinc(ii) is 55.5 and 150.8 μM for PC-3 and PNT1A, respectively. MTT-determined IC(50) are >1.3-fold higher. Impedance-based viability correlates with viable count (r > 0.92; p < 0.03), not with MTT. Two-fold lower intracellular zinc(ii) in the tumour PC-3 cell line was found. After zinc(ii) treatment >2.6-fold increase of intracellular zinc(ii) was observed in non-tumour PNT1A and in tumour PC-3 cells. In PC-3 cells, free and bound zinc(ii) levels were enhanced more markedly as compared to PNT1A. PNT1A produced 4.2-fold less MT compared to PC3. PNT1A cells showed a 4.8-fold increase trend (r = 0.94; p = 0.005); PC-3 did show a significant trend at MT1 and MT2 protein levels (r = 0.93; p = 0.02) with nearly ten-fold increase after 100 μM zinc(ii) treatment. In terms of redox state, PNT1A had a predominance of reduced GSH forms (GSH : GSSG ratio > 1), when exposed to zinc(ii) compared to PC3, where predominance of oxidised forms remains at all concentrations. IC(50) differs significantly when determined by MTT and real-time impedance-based assays due to dependence of impedance on cell morphology and adhesion. When real-time growth monitoring, precise electrochemical methods and fluorescent microscopy are performed together, accurate information for metal fluxes, their buffering by thiol compounds and monitoring of the redox state become a powerful tool for understanding the role of oxidative stress in carcinogenesis.
- MeSH
- buňky - růstové procesy účinky léků MeSH
- fluorescenční barviva chemie MeSH
- fluorescenční mikroskopie metody MeSH
- formazany chemie MeSH
- glutathion metabolismus MeSH
- impedanční spektroskopie MeSH
- lidé MeSH
- lineární modely MeSH
- metalothionein genetika metabolismus MeSH
- nádorové buněčné linie MeSH
- nádory prostaty farmakoterapie metabolismus patologie MeSH
- oxidace-redukce MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- RNA chemie genetika MeSH
- síran zinečnatý farmakologie MeSH
- tetrazoliové soli chemie MeSH
- viabilita buněk fyziologie MeSH
- western blotting MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Analysis of over 500 groundwater samples from throughout the Red River Delta indicates de-coupling of dissolved arsenic (As) and dissolved iron (Fe). Sorting of all data along the redox potentials suggests re-adsorption of As released initially from Mn(IV)-oxyhydroxides and later from Fe(III)-oxyhydroxides on remaining ferric phases at moderate redox levels. A gradually decreasing specific surface area available for re-adsorption of As probably plays a role as a consequence of limited reactivity of more crystalline phases such as goethite and hematite. At low redox levels, concentrations of Fe and phosphate decrease, but As concentrations keep increasing and most As is present as As(III) with limited adsorption affinity. Based on the results of speciation modeling, the water is supersaturated with respect to siderite and vivianite. A general conceptual model of As and Fe behavior is presented, suggesting that coupled behavior is possible in two geochemical "windows", i.e., 1: between saturation of remaining adsorption sites and the onset of siderite and vivianite precipitation, and 2: after the beginning of secondary sulfide phases precipitation and during methanogenesis. The de-coupling of As from Fe is common and has been observed at many sites around the world where As is released as a consequence of redox processes, e.g., in Bangladesh, West Bengal and Assam in India, the Mekong Delta in Cambodia and Vietnam, and Taiwan. The presented general conceptual model of de-coupling processes can be applied to the interpretation of As and Fe data, and, thus, it can help in the preparation of a site conceptual model which is a necessary prerequisite for reactive transport modeling.
- MeSH
- arsen analýza MeSH
- chemické látky znečišťující vodu MeSH
- epidemiologické monitorování MeSH
- geologické sedimenty analýza chemie MeSH
- monitorování životního prostředí metody MeSH
- oxidace-redukce MeSH
- řeky MeSH
- teoretické modely MeSH
- uhličitany MeSH
- železité sloučeniny analýza MeSH
- železo analýza MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Bangladéš MeSH
- Indie MeSH
- Kambodža MeSH
- Taiwan MeSH
- Vietnam MeSH
Redox signaling from mitochondria (mt) to the cytosol and plasma membrane (PM) has been scarcely reported, such as in the case of hypoxic cell adaptation or (2-oxo-) 2-keto-isocaproate (KIC) β-like-oxidation stimulating insulin secretion in pancreatic β-cells. Mutual redox state influence between mitochondrial major compartments, the matrix and the intracristal space, and the cytosol is therefore derived theoretically in this article to predict possible conditions, when mt-to-cytosol and mt-to-PM signals may occur, as well as conditions in which the cytosolic redox signaling is not overwhelmed by the mitochondrial antioxidant capacity. Possible peroxiredoxin 3 participation in mt-to-cytosol redox signaling is discussed, as well as another specific case, whereby mitochondrial superoxide release is diminished, whereas the matrix MnSOD is activated. As a result, the enhanced conversion to H2O2 allows H2O2 diffusion into the cytosol, where it could be a predominant component of the H2O2 release. In both of these ways, mt-to-cytosol and mt-to-PM signals may be realized. Finally, the use of redox-sensitive probes is discussed, which disturb redox equilibria, and hence add a surplus redox-buffering to the compartment, where they are localized. Specifically, when attempts to quantify net H2O2 fluxes are to be made, this should be taken into account.
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The effect of illumination and molecular oxygen on the redox and the redox potential changes of cytochrome b(559) (cyt b(559)) has been studied in Tris-treated spinach photosystem II (PSII) membranes. It has been demonstrated that the illumination of Tris-treated PSII membranes induced the conversion of the intermediate-potential (IP) to the reduced high-potential (HP(Fe2+)) form of cyt b(559), whereas the removal of molecular oxygen resulted in the conversion of the IP form to the oxidized high-potential (HP(Fe3+)) form of cyt b(559). Light-induced conversion of cyt b(559) from the IP to the HP form was completely inhibited above pH 8 or by the modification of histidine ligand that prevents its protonation. Interestingly, no effect of high pH or histidine modification was observed during the conversion of the IP to the HP form of cyt b(559) after the removal of molecular oxygen. These results indicate that conversion from the IP to the HP form of cyt b(559) proceeds via different mechanisms. Under illumination, conversion of the IP to the HP form of cyt b(559) depends primarily on the protonation of the histidine residue, whereas under anaerobic conditions, the conversion of the IP to the HP form of cyt b(559) is driven by higher hydrophobicity of the environment around the heme iron resulting from the absence of molecular oxygen.
- MeSH
- chemické modely MeSH
- cytochromy typu b chemie metabolismus MeSH
- fotosystém II (proteinový komplex) chemie metabolismus MeSH
- histidin chemie metabolismus MeSH
- koncentrace vodíkových iontů MeSH
- kyslík metabolismus farmakologie MeSH
- oxidace-redukce účinky léků účinky záření MeSH
- potenciometrie MeSH
- rostlinné proteiny chemie metabolismus MeSH
- spektrofotometrie MeSH
- Spinacia oleracea metabolismus MeSH
- světlo MeSH
- tromethamin chemie farmakologie MeSH
- tylakoidy účinky léků metabolismus účinky záření MeSH
- železité sloučeniny chemie metabolismus MeSH
- železnaté sloučeniny chemie metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The current understanding of lipid droplets (LDs) in cell biology has evolved from being viewed merely as storage compartments. LDs are now recognized as metabolic hubs that act as cytosolic buffers against the detrimental effects of free fatty acids (FAs). Upon activation, FAs traverse various cellular pathways, including oxidation in mitochondria, integration into complex lipids, or storage in triacylglycerols (TGs). Maintaining a balance among these processes is crucial in cellular FA trafficking, and under metabolically challenging circumstances the routes of FA metabolism adapt to meet the current cellular needs. This typically involves an increased demand for anabolic intermediates or energy and the prevention of redox stress. Surprisingly, LDs accumulate under certain conditions such as amino acid starvation. This review explores the biochemical aspects of FA utilization in both physiological contexts and within cancer cells, focusing on the metabolism of TGs, cholesteryl esters (CEs), and mitochondrial FA oxidation. Emphasis is placed on the potential toxicity associated with non-esterified FAs in cytosolic and mitochondrial compartments. Additionally, we discuss mechanisms that lead to increased LD biogenesis due to an inhibited mitochondrial import of FAs.
New screen-printed sensor with a boron-doped diamond working electrode (SP/BDDE) was fabricated using a large-area linear antenna microwave chemical deposition vapor system (LA-MWCVD) with a novel precursor composition. It combines the advantages of disposable printed sensors, such as tailored design, low cost, and easy mass production, with excellent electrochemical properties of BDDE, including a wide available potential window, low background currents, chemical resistance, and resistance to passivation. The newly prepared SP/BDDEs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. Their electrochemical properties were investigated by cyclic voltammetry and electrochemical impedance spectroscopy using inner sphere ([Fe(CN)6]4-/3-) and outer sphere ([Ru(NH3)6]2+/3+) redox probes. Moreover, the applicability of these new sensors was verified by analysis of the anti-inflammatory drug lornoxicam in model and pharmaceutical samples. Using optimized differential pulse voltammetry in Britton-Robinson buffer of pH 3, detection limits for lornoxicam were 9 × 10-8 mol L-1. The oxidation mechanism of lornoxicam was investigated using bulk electrolysis and online electrochemical cell with mass spectrometry; nine distinct reaction steps and corresponding products and intermediates were identified.
- MeSH
- bor * chemie MeSH
- elektrody MeSH
- elektrolýza * MeSH
- oxidace-redukce MeSH
- Ramanova spektroskopie MeSH
- Publikační typ
- časopisecké články MeSH
New type of bismuth film electrode prepared by electrodeposition of bismuth film on a silver solid amalgam substrate (BiF-AgSAE) was tested as a sensor for voltammetric determination of electrochemically reducible organic substances using 2-amino-6-nitrobenzothiazole (ANBT) as a model analyte. Using the optimized conditions (a 9:1 (v/v) mixture of aqueous Britton-Robinson buffer solution (pH 10.0) and methanol), the limits of quantification are 0.16 μmol L(-1) for direct current voltammetry (DCV) and 0.22 μmol L(-1) for differential pulse voltammetry (DPV). The obtained calibration dependences are linear in the concentration range from 0.2 to 100 μmol L(-1) and the practical applicability of the newly developed electrode for the direct determination of ANBT in tap and mineral water model samples was confirmed in the concentration range from 0.2 to 10 μmol L(-1).
The external pH affects both ethanol and oxygen uptake rates by nongrowing cells of Candida utilis suspended either in distilled water or in phthalate buffer. The buffering properties of organic acids control the maximum rates of exogenous respiration and ethanol uptake. The substrate limitation of ethanol uptake rate and endogenous respiration rate increase proportionally with increasing hydrogen ion concentration in the medium.
