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.

• Klíčová slova
• H2O2 release into intracristal space, MnSOD, cytosolic H2O2 release, matrix H2O2 release, peroxiredoxins, redox buffers, redox signaling from mitochondria, redox-sensitive probes,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

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.

• MeSH
• antioxidancia metabolismus   MeSH
• beta-buňky metabolismus   MeSH
• lidé MeSH
• mitochondrie * metabolismus   MeSH
• oxidace-redukce * MeSH
• oxidační stres fyziologie   MeSH
• signální transdukce fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• antioxidancia MeSH

The stabilization of the reduction state of proteins and peptides is very important for the monitoring of protein-protein, protein-DNA and protein-xenobiotic interactions. The reductive state of protein or peptide is characterized by the reactive sulfhydryl group. Glutathione in the reduced (GSH) and oxidized (GSSG) forms was studied by cyclic voltammetry. Tris(2-carboxyethyl)phosphine (TCEP) as the disulfide bond reductant and/or hydrogen peroxide as the sulfhydryl group oxidant were used. Cyclic voltammetry measurements, following the redox state of glutathione, were performed on a hanging mercury drop electrode (HMDE) in borate buffer (pH 9.2). It was shown that in aqueous solutions TCEP was able to reduce disulfide groups smoothly and quantitatively. The TCEP response at -0.25 V vs. Ag/AgCl/3 M KCl did not disturb the signals of the thiol/disulfide redox couple. The origin of cathodic and anodic signals of GSH (at -0.44 and -0.37 V) and GSSG (at -0.69 and -0.40 V) glutathione forms is discussed. It was shown that the application of TCEP to the conservation of sulfhydryl groups in peptides and proteins can be useful instrument for the study of peptides and proteins redox behavior.

• MeSH
• biokompatibilní materiály chemie   MeSH
• disulfidy analýza   chemie   MeSH
• elektrochemie metody   MeSH
• fosfiny chemie   MeSH
• glutathion analýza   chemie   MeSH
• glutathiondisulfid analýza   chemie   MeSH
• oxidace-redukce MeSH
• testování materiálů metody   MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• biokompatibilní materiály MeSH
• disulfidy MeSH
• fosfiny MeSH
• glutathion MeSH
• glutathiondisulfid MeSH
• tris(2-carboxyethyl)phosphine MeSH Prohlížeč

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.

• Klíčová slova
• Arsenic, De-coupling, Fe speciation, Iron, Red River Delta, Reductive dissolution,
• 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 epidemiologie   MeSH
• Názvy látek
• arsen MeSH
• chemické látky znečišťující vodu MeSH
• siderite MeSH Prohlížeč
• uhličitany MeSH
• železité sloučeniny MeSH
• železo MeSH

2D transition metal carbides and/or nitrides, so-called MXenes, are noted as ideal fast-charging cation-intercalation electrode materials, which nevertheless suffer from limited specific capacities. Herein, it is reported that constructing redox-active phosphorus-oxygen terminals can be an attractive strategy for Nb4 C3 MXenes to remarkably boost their specific capacities for ultrafast Na+ storage. As revealed, redox-active terminals with a stoichiometric formula of PO2 - display a metaphosphate-like configuration with each P atom sustaining three PO bonds and one PO dangling bond. Compared with conventional O-terminals, metaphosphate-like terminals empower Nb4 C3 (denoted PO2 -Nb4 C3 ) with considerably enriched carrier density (fourfold), improved conductivity (12.3-fold at 300 K), additional redox-active sites, boosted Nb redox depth, nondeclined Na+ -diffusion capability, and buffered internal stress during Na+ intercalation/de-intercalation. Consequently, compared with O-terminated Nb4 C3 , PO2 -Nb4 C3 exhibits a doubled Na+ -storage capacity (221.0 mAh g-1 ), well-retained fast-charging capability (4.9 min at 80% capacity retention), significantly promoted cycle life (nondegraded capacity over 2000 cycles), and justified feasibility for assembling energy-power-balanced Na-ion capacitors. This study unveils that the molecular-level design of MXene terminals provides opportunities for developing simultaneously high-capacity and fast-charging electrodes, alleviating the energy-power tradeoff typical for energy-storage devices.

• Klíčová slova
• MXenes, hybrid-ion capacitors, redox-active terminals, sodium-ion storage,
• Publikační typ
• časopisecké články MeSH

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
• Názvy látek
• fluorescenční barviva MeSH
• formazany MeSH
• glutathion MeSH
• metalothionein MeSH
• MT1A protein, human MeSH Prohlížeč
• MTT formazan MeSH Prohlížeč
• RNA MeSH
• síran zinečnatý MeSH
• tetrazoliové soli MeSH

The antioxidant properties of flavonoids are mediated by their functional hydroxyl groups, which are capable of both chelating redox active metals such as iron, copper and scavenging free radicals. In this paper, the antioxidant vs. prooxidant and DNA protecting properties of baicalein and Cu(II)-baicalein complexes were studied under the conditions of the Copper-Fenton reaction and of the Copper-Ascorbate system. From the relevant EPR spectra, the interaction of baicalein with Cu(II) ions was confirmed, while UV-vis spectroscopy demonstrated a greater stability over time of Cu(II)-baicalein complexes in DMSO than in methanol and PBS and Phosphate buffers. An ABTS study confirmed a moderate ROS scavenging efficiency, at around 37%, for both free baicalein and Cu(II)-baicalein complexes (in the ratios 1:1 and 1:2). The results from absorption titrations are in agreement with those from viscometric studies and confirmed that the binding mode between DNA and both free baicalein and Cu-baicalein complexes, involves hydrogen bonds and van der Waals interactions. The DNA protective effect of baicalein has been investigated by means of gel electrophoresis under the conditions of the Cu-catalyzed Fenton reaction and of the Cu-Ascorbate system. In both cases, it was found that, at sufficiently high concentrations, baicalein offers some protection to cells from DNA damage caused by ROS (singlet oxygen, hydroxyl radicals and superoxide radical anions). Accordingly, baicalein may be useful as a therapeutic agent in diseases with a disturbed metabolism of redox metals such as copper, for example Alzheimer's disease, Wilson's disease and various cancers. While therapeutically sufficient concentrations of baicalein may protect neuronal cells from Cu-Fenton-induced DNA damage in regard to neurological conditions, conversely, in the case of cancers, low concentrations of baicalein do not inhibit the pro-oxidant effect of copper ions and ascorbate, which can, in turn, deliver an effective damage to DNA in tumour cells.

• Klíčová slova
• Antioxidant, Baicalein, Copper(II), DNA damage, Gel electrophoresis, Prooxidant, Radical scavenging, Spectroscopy,
• MeSH
• antioxidancia * chemie   MeSH
• DNA metabolismus   MeSH
• flavonoidy MeSH
• hydroxylový radikál metabolismus   MeSH
• kovy MeSH
• kyselina askorbová MeSH
• měď * chemie   MeSH
• oxidace-redukce MeSH
• poškození DNA MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antioxidancia * MeSH
• baicalein MeSH Prohlížeč
• DNA MeSH
• flavonoidy MeSH
• hydroxylový radikál MeSH
• kovy MeSH
• kyselina askorbová MeSH
• měď * MeSH
• reaktivní formy kyslíku MeSH

Effects of ethanol inhibition, initial pH and buffering capacity of media on the catabolic activity of nongrowing cells of Candida utilis were studied. Effects of external conditions on the kinetic of ethanol oxidation and cell respiration are described by mathematical models. The results revealed a significant influence of both the external pH and the buffering capacity of the medium on the kinetic parameters of catabolic activity. The inhibitory effect results in the bottleneck of one of the reaction of the citrate cycle, glyoxylate cycle or electron transfer in a respiratory chain although the total rate of ethanol dissimilation increases under these conditions.

• MeSH
• aerobióza MeSH
• Candida účinky léků   metabolismus   MeSH
• energetický metabolismus MeSH
• ethanol metabolismus   MeSH
• kinetika MeSH
• koncentrace vodíkových iontů MeSH
• kultivační média farmakologie   MeSH
• oxidace-redukce MeSH
• pufry MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ethanol MeSH
• kultivační média MeSH
• pufry MeSH

The measurements of oxidation-reduction potentials at pH 7.0 and ionic strength of 0.1 revealed only a slight difference between human adult (HbA) and foetal haemoglobin (HbF) (161 and 145 mV), which disappeared on increasing the ionic strength to 2.1. Kinetic data for the reactions with potassium ferricyanide and sodium nitrite of both haemoglobins in oxy- and carbonmonoxi-forms are presented at different excessive molar concentrations of oxidizing agents, in different environments at pH 7.0 and temperature ranging from 10--30 degrees C. The rate of HbF oxidation was considerably higher with both agents, despite vast differences in the reaction mechanisms.

• MeSH
• dospělí MeSH
• dusitany krev   MeSH
• ferrikyanidy krev   MeSH
• fetální hemoglobin metabolismus   MeSH
• hemoglobiny metabolismus   MeSH
• kinetika MeSH
• koncentrace vodíkových iontů MeSH
• lidé MeSH
• oxidace-redukce MeSH
• oxyhemoglobiny metabolismus   MeSH
• pufry MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dusitany MeSH
• ferrikyanidy MeSH
• fetální hemoglobin MeSH
• hemoglobiny MeSH
• oxyhemoglobiny MeSH
• pufry MeSH

meso-Tetra(4-sulfonatophenyl)porphyrin (TPPS4) is a water soluble photosensitizer, which is currently clinically tested as a PDT drug. In our contribution, we present IR spectral- and time-resolved phosphorescence data reflecting the influence of human serum albumin (HSA) on singlet oxygen photogeneration by TPPS4. IR emission of TPPS4 was studied in samples containing various concentrations of HSA in phosphate buffer. The observed changes in spectral and temporal behaviour of TPPS4 and singlet oxygen phosphorescence caused by the addition of HSA are equivalent to the effect of nitrogen purging of HSA-free solutions of TPPS4. The main feature induced by addition of HSA appears to be the occurrence of a long-lived (tens of microseconds) photosensitizer phosphorescence at 900 nm besides ordinary short-lived (approximately 2 micros) one at 820 nm. It is accompanied by presence of a long-lived component of singlet oxygen emission with lifetime roughly corresponding to that of the long photosensitizer phosphorescence component. Moreover, the quantum yield of singlet oxygen phosphorescence decreases with increasing HSA concentration, while total quantum yield of TPPS4 phosphorescence rises. These facts are explained by a shielding effect of HSA on bound molecules of TPPS4 against quenching by oxygen which is analogous to oxygen removal by nitrogen purging.

• MeSH
• fosfáty chemie   MeSH
• fotosenzibilizující látky chemie   MeSH
• kinetika MeSH
• koncentrace vodíkových iontů MeSH
• lidé MeSH
• oxidace-redukce MeSH
• porfyriny chemie   MeSH
• pufry MeSH
• sérový albumin chemie   MeSH
• singletový kyslík chemie   MeSH
• spektrofotometrie infračervená metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fosfáty MeSH
• fotosenzibilizující látky MeSH
• porfyriny MeSH
• pufry MeSH
• sérový albumin MeSH
• singletový kyslík MeSH
• tetraphenylporphine sulfonate MeSH Prohlížeč