Zeitschriftenartikel: „Thiols“

1

Zelli, Renaud, Pascal Dumy und Alberto Marra. „Metal-free synthesis of imino-disaccharides and calix-iminosugars by photoinduced radical thiol–ene coupling (TEC)“. Organic & Biomolecular Chemistry 18, Nr. 13 (2020): 2392–97. http://dx.doi.org/10.1039/d0ob00198h.

Der volle Inhalt der Quelle

Annotation:

Deprotected iminosugar alkenes were subjected to thiol–ene coupling with deprotected sugar thiols to afford new imino-disaccharides. Two thiol–ene couplings converted these alkenes into iminosugar thiols and then multivalent iminosugars.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

2

YILMAZ, Yücel, Şaban KELEŞOĞLU, Kemal TEKİN, Bekir ÇALAPKORUR, Özcan EREL, Salim NEŞELİOĞLU und Deniz ELCİK. „A New Biomarker in The Distinction Between Stable Coronary Artery Disease and Acute Coronary Syndrome:Thiols“. Journal of Contemporary Medicine 12, Nr. 4 (01.06.2022): 1–6. http://dx.doi.org/10.16899/jcm.981853.

Der volle Inhalt der Quelle

Annotation:

Backraund; Thiols are important elements for oxidation reactions and under oxidative stress. The aim of this study was to determine thiole levels, an antioxidative marker in CAD patients with stable and acute coronary syndrome. Methods; 210 of the patients included in the study were diagnosed with acute coronary syndrome (ACS), 205 consisted of patients with stable angina pectoris (SAP). Thiol groups levels and thiol/disulphide homeostasis was measured by spectrophotometrically. Results: Native thiol and total thiol levels, disulfide/natural thiol and disulfide/total thiol ratios were decreased in the ACS groups compared to the SAP groups Conclusions: Thiol levels and thiol / disulfide ratios can be used as markers to evaluate acute coronary syndrome.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

3

Kalyanaraman, B. „Thiyl radicals in biological systems: significant or trivial?“ Biochemical Society Symposia 61 (01.11.1995): 55–63. http://dx.doi.org/10.1042/bss0610055.

Der volle Inhalt der Quelle

Annotation:

Thiyl radicals are formed from one-electron oxidation of thiols. Thiyl radicals participate in a number of reactions including electron transfer, hydrogen abstraction and addition reactions with several biological constituents and xenobiotics. Thiyl radicals can be detected by optical spectroscopy or by electron spin resonance (ESR) spectroscopy. Thiyl radicals appear to play a role in the nitrosylation of thiols and protein thiols. The exact mechanism of thiol-induced enhancement of oxidative modification of low-density lipoprotein remains questionable. The proposed role of thiyl radicals in lipid peroxidation needs to be re-examined. It has been proposed that thiyl radicals are detoxified by superoxide dismutase in mammalian cells and by a thiol-specific enzyme in bacterial systems. We propose that thiols or protein thiols act as potent antioxidants in radical-induced damage via formation of thiyl radicals.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

4

Skalska, Jolanta, Paul S. Brookes, S. M. Nadtochy, Shannon Hilchey, Craig T. Jordan, Monica L. Guzman, Sanjay Maggirwar, Margaret M. Briehl und Steven H. Bernstein. „Modulation of Cell Surface Protein Free Thiols; A Potential Novel Mechanism of Action of the Sesquiterpene Lactone Parthenolide in Non-Hodgkin's Lymphoma.“ Blood 114, Nr. 22 (20.11.2009): 3774. http://dx.doi.org/10.1182/blood.v114.22.3774.3774.

Der volle Inhalt der Quelle

Annotation:

Abstract Abstract 3774 Poster Board III-710 Recent data supports the concept that redox regulation of cell surface protein thiols (i.e., exofacial thiols) effects critical cellular functions. We therefore hypothesized that redox-active anti-cancer therapeutics would modulate exofacial thiols, and that such modulation could be related to cell death mechanisms. To test this hypothesis, we used the sesquiterpene lactone parthenolide, a known anti-cancer agent. Parthenolide treatment results in a dose dependent decrease in mantle cell (MCL) and diffuse large cell lymphoma cell viability. Indeed, parthenolide decreases the level of free (ie. reduced) exofacial thiols on Granta MCL cells as assessed by flow cytometry. Parthenolide specifically modifies free thiols of surface proteins having molecular weights of ∼12 kd and ∼22 kd, as determined using a biotinylated thiol reactive reagent N-(biotinoyl)-N-(iodoacetyl) ethylendiamine (BIAM), which binds to free thiol groups and is detected by streptavidin-peroxidase staining of western blots. We further show that the central redox regulator thioredoxin is one of the surface protein thiol targets modified by parthenolide; specifically; (a) thioredoxin is detected on the Granta cell surface; (b) parthenolide directly interacts with free thiol groups on purified human thioredoxin, and; (c) parthenolide directly modifies Granta membrane associated thioredoxin, as determined with BIAM and neutravidin pull-down. To examine the functional consequences of parthenolide induced surface protein thiol modification, Granta cells were pretreated with the cell impermeable thiol antioxidant glutathione (GSH). Pretreatment with GSH inhibits the parthenolide induced; (a) decrease in exofacial free thiols; (b) modification of surface thioredoxin and; (c) Granta cell death. Pretreatment of Granta cells with GSH also inhibits parthenolide-mediated activation of JNK and inhibition of NFkB, two activities previously associated with the drug's anti-cancer activity. Based on these data, we postulate that at least one component of parthenolide's anti-lymphoma activity derives from its ability to modify the redox state of critical exofacial thiols. Indeed, to our knowledge, our data is the first to suggest that cancer cell exofacial thiols may be novel and important targets for cancer therapy. Supported by an NCI SPORE grant in lymphoma 1P50 CA130805. Disclosures: Bernstein: millenium: Consultancy; genentech: Consultancy, Speakers Bureau; enzon: Consultancy.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

5

Sawada, K., B. C. W. Hummel und P. G. Walfish. „Intermediate Mr cytosolic components potentiate hepatic 5′-deiodinase activation by thiols“. Biochemical Journal 238, Nr. 3 (15.09.1986): 787–91. http://dx.doi.org/10.1042/bj2380787.

Der volle Inhalt der Quelle

Annotation:

The role in the activation of microsomal 5′-deiodinase (5′-DI) of rat hepatic cytosolic components of Mr approx. 13,000 (Fraction B) was studied in the presence of various concentrations of thiol compounds such as dithiothreitol (DTT), dihydrolipoamide (DHLA), GSH, and 2-mercaptoethanol (2-ME). Although Fraction B (which was prepared by gel filtration to exclude GSH and GSSG) had no intrinsic 5′-DI activity, could not stimulate microsomal 5′-DI activity in the absence of added thiol and did not contain GSH as a mixed disulphide, it could produce a 3-fold increase in the maximal deiodinase activity achievable with DTT as well as other thiols, with the order being the same as the activation potency of these thiols in the absence of Fraction B (i.e. DHLA greater than DTT greater than 2-ME greater than GSH). These observations suggest that: a component of cytosolic Fraction B, designated ‘deiodination factor B’ (DFB), operates as an efficient intermediary to enhance activation of microsomal 5′-DI by thiols through a mechanism independent of GSH; thiols may participate in a non-specific thiol-disulphide exchange with inactive (oxidized) DFB to convert it into an active form that contains one or more thiol groups and is more effective than GSH or other thiols in facilitating the re-activation of inactive (oxidized) microsomal 5′-DI thiol (ESI) to its active state (ESH).

APA, Harvard, Vancouver, ISO und andere Zitierweisen

6

MANDAL, G., S. WYLLIE, N. SINGH, S. SUNDAR, A. H. FAIRLAMB und M. CHATTERJEE. „Increased levels of thiols protect antimony unresponsive Leishmania donovani field isolates against reactive oxygen species generated by trivalent antimony“. Parasitology 134, Nr. 12 (05.07.2007): 1679–87. http://dx.doi.org/10.1017/s0031182007003150.

Der volle Inhalt der Quelle

Annotation:

SUMMARYThe current trend of antimony (Sb) unresponsiveness in the Indian subcontinent is a major impediment to effective chemotherapy of visceral leishmaniasis (VL). Although contributory mechanisms studied in laboratory-raised Sb-R parasites include an up-regulation of drug efflux pumps and increased thiols, their role in clinical isolates is not yet substantiated. Accordingly, our objectives were to study the contributory role of thiols in the generation of Sb unresponsiveness in clinical isolates. Promastigotes were isolated from VL patients who were either Sb responsive (n=2) or unresponsive (n=3). Levels of thiols as measured by HPLC and flow cytometry showed higher basal levels of thiols and a faster rate of thiol regeneration in Sb unresponsive strains as compared with sensitive strains. The effects of antimony on generation of reactive oxygen species (ROS) in normal and thiol-depleted conditions as also their H2O2 scavenging activity indicated that in unresponsive parasites, Sb-mediated ROS generation was curtailed, which could be reversed by depletion of thiols and was accompanied by a higher H2O2 scavenging activity. Higher levels of thiols in Sb-unresponsive field isolates from patients with VL protect parasites from Sb-mediated oxidative stress, thereby contributing to the antimony resistance phenotype.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

7

Folikumah, Makafui Y., Marc Behl und Andreas Lendlein. „Reaction behaviour of peptide-based single thiol-thioesters exchange reaction substrate in the presence of externally added thiols“. MRS Communications 11, Nr. 4 (14.07.2021): 402–10. http://dx.doi.org/10.1557/s43579-021-00041-z.

Der volle Inhalt der Quelle

Annotation:

Abstract Identification of patterns in chemical reaction pathways aids in the effective design of molecules for specific applications. Here, we report on model reactions with a water-soluble single thiol-thioester exchange (TTE) reaction substrate, which was designed taking in view biological and medical applications. This substrate consists of the thio-depsipeptide, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH (TDP) and does not yield foul-smelling thiol exchange products when compared with aromatic thiol containing single TTE substrates. TDP generates an α,ω-dithiol crosslinker in situ in a ‘pseudo intramolecular’ TTE. Competitive intermolecular TTE of TDP with externally added “basic” thiols increased the crosslinker concentration whilst “acidic” thiols decreased its concentration. TDP could potentially enable in situ bioconjugation and crosslinking applications. Graphic abstract The competition between ‘pseudo intramolecular’ and intermolecular exchange of a peptide-based thiol-thioester exchange (TTE) substrate can be used to control the relative amount of final exchange products based on size and pKa values of externally added thiols. Potential application of this system can be seen in the development of TTE substrates for the rapid identification of thiols by dynamic combinatorial screening.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

8

Steenkamp, D. J. „Simple methods for the detection and quantification of thiols from Crithidia fasciculata and for the isolation of trypanothione“. Biochemical Journal 292, Nr. 1 (15.05.1993): 295–301. http://dx.doi.org/10.1042/bj2920295.

Der volle Inhalt der Quelle

Annotation:

Methods for the qualitative and quantitative analysis of thiols by means of the fluorogenic reagent 7-diethylamino-3-(4′-maleimidylphenyl)-4-methylcoumarin are described, with particular reference to the trypanosomatid metabolites glutathionylspermidine (GSH-spermidine) and trypanothione. Second-order rate constants for the derivatization of seven different thiols under defined experimental conditions and at 21 degrees C varied between 619 +/- 34 and 10,560 +/- 236 M-1.s-1.T.l.c. of the thiols from Crithidia fasciculata was used to monitor the purification of trypanothione from this organism in three steps involving adsorption, ion-exchange and reversed-phase chromatography. The yield was approx. 50 mg of pure trypanothione from 100 g (wet wt.) of trypanosomatids. The method for the quantitative analysis of biological thiols is based on fluorometric detection after separation by reversed-phase or ion-paired chromatography on a phenyl-silica column. Analysis of the thiol composition of cell lysates prepared under nondenaturating conditions point to the rapid degradation of the GSH-spermidine conjugates. In addition to GSH, GSH-spermidine and trypanothione, at least one other prominent thiol was detected, and the contribution of this thiol to the total thiol content in the various growth phases of C. fasciculata was investigated.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

9

Liu, Zhengkun, Qianqian Wang, Hao Wang, Wenting Su und Shouliang Dong. „A FRET Based Two-Photon Fluorescent Probe for Visualizing Mitochondrial Thiols of Living Cells and Tissues“. Sensors 20, Nr. 6 (21.03.2020): 1746. http://dx.doi.org/10.3390/s20061746.

Der volle Inhalt der Quelle

Annotation:

Glutathione (GSH) is the main component of the mitochondrial thiol pool and plays key roles in the biological processes. Many evidences have suggested that cysteine and homocysteine also exist in mitochondria and are interrelated with GSH in biological systems. The fluctuation of the levels of mitochondrial thiols has been linked to many diseases and cells’ dysfunction. Therefore, the monitoring of mitochondrial thiol status is of great significance for clinical studies. We report here a novel fluorescence resonance energy transfer based two-photon probe MT-1 for mitochondrial thiols detection. MT-1 was constructed by integrating the naphthalimide moiety (donor) and rhodamine B (accepter and targeting group) through a newly designed linker. MT-1 shows a fast response, high selectivity, and sensitivity to thiols, as well as a low limit of detection. The two-photon property of MT-1 allows the direct visualization of thiols in live cells and tissues by two-photon microscopy. MT-1 can serve as an effective tool to unravel the diverse biological functions of mitochondrial thiols in living systems.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

10

Cavalli, Federica, Lies De Keer, Birgit Huber, Paul H. M. Van Steenberge, Dagmar R. D'hooge und Leonie Barner. „A kinetic study on the para-fluoro-thiol reaction in view of its use in materials design“. Polymer Chemistry 10, Nr. 22 (2019): 2781–91. http://dx.doi.org/10.1039/c9py00435a.

Der volle Inhalt der Quelle

Annotation:

A detailed kinetic study on the para-fluoro-thiol reaction (PFTR) using experimental analysis and kinetic Monte Carlo modeling is introduced, covering the difference in reactivity of a selected variety of structurally different thiols, uniquely including polymeric thiols.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

11

Jaschke, M., H. Wolf, H. Schönherr, H. Ringsdorf, E. Bamberg und H. J. Butt. „The molecular structure of thiol-monolayers on gold imaged with an Atomic Force Microscope“. Proceedings, annual meeting, Electron Microscopy Society of America 53 (13.08.1995): 714–15. http://dx.doi.org/10.1017/s0424820100139949.

Der volle Inhalt der Quelle

Annotation:

Thiols spontaneously form monolayers on gold. An important question is which factors determine the structure of the thiols. The two extreme positions are: (a) the structure of the underlying gold determines the packing of the thiol molecules; (b) the geometry of the thiol molecules and the interaction between thiols determine their two-dimensional structure.To help answer this question two series of thiol molecules on gold (111) were imaged by atomic force microscopy. In order to reduce the force between tip and sample, and to prevent distortion of the thiol monolayer, all images were taken in ethanol at forces between 0.5 nN and 3 nN.The first series consisted of several azobenzene-thiols:Although these molecules possess a terminal alkyl chain, their lattice is different from the well known hexagonal (√3 × √3) R 30° lattice (with respect to the underlying gold (111) lattice) of alkane-thiols. Instead, we found two stable rectangular lattices which could both be described by lattice constants of 0.61 nm and 0.79 nm, and an angle of 89°. These structures were also found on polycrystalline gold. Also, varying the length of the alkyl chain (molecules (i) and (ii)) or using a disulfide instead of a thiol (molecules (ii) and (iii)) did not change the lattice constants. Thus we conclude that the lattice for azobenzenethiols is end-group dominated.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

12

Copper, Alexander Willem, Cassandra Collins, Susan E. P. Bastian, Trent E. Johnson und Dimitra L. Capone. „Preliminary investigation of potent thiols in Cypriot wines made from indigenous grape varieties Xynisteri, Maratheftiko and Giannoudhi“. OENO One 55, Nr. 1 (03.03.2021): 223–34. http://dx.doi.org/10.20870/oeno-one.2021.55.1.4516.

Der volle Inhalt der Quelle

Annotation:

Polyfunctional thiols have previously been shown to be key aroma compounds in Sauvignon blanc and more recently in Chardonnay wines. Their role in other wine varieties such as those made from three popular indigenous Cypriot grape varieties has remained unexplored. As an extension of a previous project that profiled the sensory and chemical characteristics of Cypriot wines and their comparison to Australian wines, this study aimed to investigate five potent thiols in Xynisteri, Maratheftiko, Giannoudhi, Pinot gris, Chardonnay and Shiraz wines. Wines were analysed utilising Stable Isotope Dilution Assay (SIDA) with derivatisation and High-Performance Liquid Chromatography–Tandem Mass Spectrometry (HPLC-MS/MS). The varietal thiols measured were 4-methyl-4-sulfanylpentan-2-one (4MSP) that has an aroma of “boxwood” and “cat urine” at high concentration, 3-sulfanylhexan-1-ol (3SH) which has been described as having a “grapefruit/tropical fruit” aroma, and 3-sulfanylhexyl acetate (3SHA) that has also been described as having an aroma of “passionfruit”. Additionally, two other potent thiols were measured including benzyl mercaptan (BM) that has an aroma of “smoke and meat” and furfuryl thiol (FFT) that has been described as having a “roasted coffee” like aroma. The reason these thiols are known as potent thiols are due to their very low aroma detection thresholds in the low ng/L (ppt) range. Of the thiols that were measured, 3SH was the only varietal thiol detected in the red wine samples. All of the white wine samples contained 3SH, BM and 3SHA, whereas 4MSP was only detected in Pinot gris and three Xynisteri wines. The potent thiol, FFT, was detected only in the Chardonnay and four of the Xynisteri wines. Interestingly the thiols that were present in the samples were found at concentrations above their aroma detection thresholds (determined in hydroalcoholic solutions), especially 3SH which was found in an order of magnitude above its aroma detection threshold. These findings provide early knowledge of the presence of these thiols in Cypriot wines, compared with Australian wines and establish any relationships between this chemical data with previous wine sensory profile data.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

13

Amir, Roey, Assaf Harnoy, Nitsan Papo und Gadi Slor. „Mixing End Groups in Thiol-Ene/Yne Reactions as a Simple Approach toward Multienzyme-Responsive Polymeric Amphiphiles“. Synlett 29, Nr. 19 (16.11.2018): 2582–87. http://dx.doi.org/10.1055/s-0037-1611340.

Der volle Inhalt der Quelle

Annotation:

Taking advantage of the high fidelity of thiol-ene and thiol-yne chemistries, we used mixtures of thiols to prepare degradable PEG-dendron amphiphiles functionalized with two different types of enzymatically cleavable end groups. By tuning the feed ratios of the two thiols, we achieved mixtures of hybrids with statistically different ratios of end groups. Studies of the disassembly of statistically mixed hybrids showed that these amphiphiles have higher degrees of response when incubated with each of the activating enzymes, whereas a greater degree of selectivity was observed for a control mixture of two distinct amphiphiles, which required the presence of both types of enzyme to undergo complete disassembly. The potential to introduce different end groups by using a mixture of thiols in an efficient single thiol-ene or thiol-yne step opens the way for simple modification of various ene- or yne-containing polymers and tailoring of their structural and functional properties.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

14

Mafata, Mpho, Maria Stander, Baptiste Thomachot und Astrid Buica. „Measuring Thiols in Single Cultivar South African Red Wines Using 4,4-Dithiodipyridine (DTDP) Derivatization and Ultraperformance Convergence Chromatography-Tandem Mass Spectrometry“. Foods 7, Nr. 9 (30.08.2018): 138. http://dx.doi.org/10.3390/foods7090138.

Der volle Inhalt der Quelle

Annotation:

Wine varietal thiols are important contributors to wine aroma. The chemical nature of thiols makes them difficult to measure due to low concentrations, high sensitivity to oxidation, and low ionization. Methods for the measurement of thiols usually consist of multiple steps of sample preparation followed by instrumental measurement. Studies have collected large datasets of thiols in white wine but not in red wine, due to the lack of availability of suitable methods. In this study, for the first time, convergence chromatography was used to measure thiols in red wine at ultratrace levels with improved sensitivity compared to previous methods. Performance parameters (selectivity, linearity, limits of detection, precision, accuracy) were tested to demonstrate the suitability of the method for the proposed application. Red wine thiols were measured in South African Pinotage, Shiraz, and Cabernet Sauvignon wines (n = 16 each). Cultivar differentiation using the thiol profile was demonstrated.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

15

P., Pullaiah, Suchitra M. M. und Siddhartha Kumar B. „Protein carbonyls and protein thiols in rheumatoid arthritis“. International Journal of Research in Medical Sciences 6, Nr. 5 (25.04.2018): 1738. http://dx.doi.org/10.18203/2320-6012.ijrms20181770.

Der volle Inhalt der Quelle

Annotation:

Background: Oxidative stress (OS) has an important role in the pathogenesis and progression of rheumatoid arthritis (RA). OS causes protein modification, thereby impairing the biological functions of the protein. This study was conducted to assess the oxidatively modified protein as protein carbonyl content and the antioxidant status as protein thiols, and to study the association between protein carbonyls and protein thiols in RA.Methods: Newly diagnosed RA patients who were not taking any disease modifying anti-rheumatic drugs were included into the study group (n=45) along with age and sex matched healthy controls (n=45). Serum protein carbonyl content and protein thiols were estimated.Results: Elevated protein carbonyl content and decreased protein thiol levels (p<0.001) were observed in RA. A significant negative correlation was observed between protein carbonyl content and protein thiol levels (p<0.001).Conclusions: Oxidative stress in RA is evidenced by enhanced protein oxidation and decreased antioxidant protein thiol levels. Decreased protein thiols may also reflect protein modifications leading to compromise in the antioxidant properties. This oxidant and antioxidant imbalance needs to be addressed by therapeutic interventions to prevent disease progression.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

16

Boekhoud, Lisanne, Jacqueline Koeze, Elisabeth C. van der Slikke, Arno R. Bourgonje, Jill Moser, Jan G. Zijlstra, Anneke C. Muller Kobold et al. „Acute Kidney Injury is Associated with Lowered Plasma-Free Thiol Levels“. Antioxidants 9, Nr. 11 (16.11.2020): 1135. http://dx.doi.org/10.3390/antiox9111135.

Der volle Inhalt der Quelle

Annotation:

Acute kidney injury (AKI) is associated with the abrupt loss of kidney function. Oxidative stress plays an important role in the pathophysiology of AKI. Free thiols (R-SH) are crucial components of the extracellular antioxidant machinery and reliably reflect systemic oxidative stress. Lower levels of thiols represent higher levels of oxidative stress. In this preliminary study, we hypothesized that plasma-free thiols are associated with AKI upon admission to the intensive care unit (ICU). In this study, 301 critically ill patients were included. Plasma samples were taken upon admission, and albumin-adjusted plasma-free thiols were determined. Albumin-adjusted plasma-free thiols were lower in patients with AKI (n = 43, median (interquartile range) 7.28 µmol/g (3.52, 8.95)) compared to patients without AKI (8.50 μmol/g (5.82, 11.28); p < 0.05) upon admission to the ICU. Higher age (B = −0.72), higher levels of neutrophil gelatinase-associated lipocalin (B = −0.002), creatinine (B = −0.01) and lower serum albumin (B = 0.47) were associated with lower free thiol levels. Further, albumin-adjusted free thiol levels were significantly reduced in patients with sepsis (8.30 (5.52–10.64) µmol/g) compared to patients without sepsis (6.95 (3.72–8.92) µmol/g; p < 0.05). Together, albumin-adjusted plasma-free thiols were significantly reduced in patients with AKI and patients with sepsis compared with patients without AKI and sepsis.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

17

Yamamoto, Hiroki, Takuya Fujiwara, Takashi Funatsu und Makoto Tsunoda. „Quantification of Intracellular Thiols by HPLC-Fluorescence Detection“. Molecules 26, Nr. 8 (19.04.2021): 2365. http://dx.doi.org/10.3390/molecules26082365.

Der volle Inhalt der Quelle

Annotation:

Biothiols, such as cysteine and glutathione, play important roles in various intracellular reactions represented by the redox equilibrium against oxidative stress. In this study, a method for intracellular thiol quantification using HPLC-fluorescence detection was developed. Thiols were derivatized with a thiol-specific fluorescence derivatization reagent, viz. ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (SBD-F), followed by reversed-phase separation on an InertSustain AQ-C18 column. Six different SBD-thiols (homocysteine, cysteine, cysteinylglycine, γ-glutamylcysteine, glutathione, and N-acetylcysteine as an internal standard) were separated within 30 min using a citric buffer (pH 3.0)/MeOH mobile phase. The calibration curves of all the SBD-thiols had strong linearity (R2 > 0.999). Using this developed method, the thiol concentrations of human chronic myelogenous leukemia K562 cell samples were found to be 5.5–153 pmol/1 × 106 cells. The time-dependent effect of a thiol scavenger, viz. N-ethyl maleimide, on intracellular thiol concentrations was also quantified. This method is useful for elucidating the role of intracellular sulfur metabolism.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

18

Chen, Liang, Dimitra L. Capone und David W. Jeffery. „Analysis of Potent Odour-Active Volatile Thiols in Foods and Beverages with a Focus on Wine“. Molecules 24, Nr. 13 (05.07.2019): 2472. http://dx.doi.org/10.3390/molecules24132472.

Der volle Inhalt der Quelle

Annotation:

Certain volatile thiols are some of the most potent odour-active molecules that are found in nature. Thiols play significant roles in the aroma qualities of a range of foods and beverages, including wine, with extremely low odour detection thresholds (nanogram per litre range). A fundamental understanding of their formation, fate, and impact essentially depends on the development of suitable analytical methods. The analysis of volatile thiols in foods and beverages is a challenging task when considering (1) the complexity of food and beverage matrices and (2) that thiols are highly reactive, low molecular-weight volatiles that are generally present at trace to ultra-trace concentrations. For the past three decades, the analytical evaluation of volatile thiols has been intensively performed in various foods and beverages, and many novel techniques related to derivatisation, isolation, separation, and detection have been developed, particularly by wine researchers. This review aims to provide an up-to-date overview of the major analytical methodologies that are proposed for potent volatile thiol analysis in wine, foods, and other beverages. The analytical challenges for thiol analysis in foods and beverages are outlined, and the main analytical methods and recent advances in methodology are summarised and evaluated for their strengths and limitations. The key analytical aspects reviewed include derivatisation and sample preparation techniques, chromatographic separation, mass spectrometric detection, matrix effects, and quantitative analysis. In addition, future perspectives on volatile thiol research are also suggested.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

19

Crmarić, Dora, und Elvira Bura-Nakić. „Interaction between Cu and Thiols of Biological and Environmental Importance: Case Study Using Combined Spectrophotometric/Bathocuproine Sulfonate Disodium Salt Hydrate (BCS) Assay“. Molecules 28, Nr. 13 (28.06.2023): 5065. http://dx.doi.org/10.3390/molecules28135065.

Der volle Inhalt der Quelle

Annotation:

Considering the biological and ecological importance of Cu–thiol interactions and the discrepancies in previous research, this study focuses on Cu interactions with biologically and ecologically relevant thiols: glutathione (GSH), L-cysteine (L-cys), 3-mercaptopropionic acid (MPA), and thioacetic acid (TAA) in aqueous solution. The addition of Cu(II) to a thiol-containing solution led to a rapid reduction of Cu(II) and the formation of a Cu(I)–thiol complex. The mechanism of Cu(II) reduction and Cu(I) complex formation as well as the kinetics of Cu(I) oxidation strongly depend on the structural properties of the individual thiols investigated. The reducing power of the investigated thiols can be summarized as follows: L-cys ≅ GSH > MPA > TAA. The reaction order, with respect to Cu(I) oxidation, also changes over the time of the reaction course. The deviation of the reaction kinetics from the first order with respect to Cu(I) in the later stages of the reaction course can be attributed to a Fenton-like reaction occurring under low thiol concentration conditions. At high Cu:thiol ratios, in the case of GSH, L-cys, and MPA, the early stage of the reaction course is characterized by high Cu(I) stability, most likely as a result of Cu(I) complexation by the thiols present in excess in the reaction mixture.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

20

Langford, C. R., D. W. Johnson und N. R. Cameron. „Chemical functionalization of emulsion-templated porous polymers by thiol–ene “click” chemistry“. Polym. Chem. 5, Nr. 21 (2014): 6200–6206. http://dx.doi.org/10.1039/c4py00713a.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

21

Hong, Seung-Mo, Oh Young Kim und Seok-Ho Hwang. „Chemistry of Polythiols and Their Industrial Applications“. Materials 17, Nr. 6 (14.03.2024): 1343. http://dx.doi.org/10.3390/ma17061343.

Der volle Inhalt der Quelle

Annotation:

Thiols can react with readily available organic substrates under benign conditions, making them suitable for use in chemical, biological, physical, and materials and engineering research areas. In particular, the highly efficient thiol-based click reaction includes the reaction of radicals with electron-rich enes, Michael addition with electron-poor enes, carbonyl addition with isocyanate SN2 ring opening with epoxies, and SN2 nucleophilic substitution with halogens. This mini review provides insights into emerging venues for their industrial applications, especially for the applications of thiol-ene, thiol–isocyanate, and thiol–epoxy reactions, highlighting a brief chemistry of thiols as well as various approaches to polythiol synthesis.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

22

Gupta, Pradeep, und Chandra Maurya. „Phosphorus Pentasulfide Mediated Conversion of Primary Carbamates into Thiols“. Synlett 28, Nr. 13 (02.05.2017): 1649–51. http://dx.doi.org/10.1055/s-0036-1589026.

Der volle Inhalt der Quelle

Annotation:

In this paper, we report a method for the conversion of primary carbamates into thiols in the presence of phosphorus pentasulfide (P2S5) in refluxing toluene. Presently, no method exists in the literature for conversion of carbamates into thiols and, to the best of our knowledge, it is the first report for this type of conversion. This method presents an indirect route for the conversion of alcohols into thiols via their carbamate derivatives that may be useful in the total synthesis of compounds containing a thiol functionality.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

23

Liszewska, F., A. Blaszczyk und A. Sirko. „Modification of non-protein thiols contents in transgenic tobacco plants producing bacterial enzymes of cysteine biosynthesis pathway.“ Acta Biochimica Polonica 48, Nr. 3 (30.09.2001): 647–56. http://dx.doi.org/10.18388/abp.2001_3899.

Der volle Inhalt der Quelle

Annotation:

Conditions of achieving the maximal accumulation of sulfhydryl metabolites in the leaves of tobacco were explored. Simultaneous production of bacterial O-acetylserine (thiol)-lyase and serine acetyltransferase resulted in the increased thiols contents as compared to single transformants and controls. However, leaf discs feeding experiments differently affected thiols concentration in different plant groups and suggested that the most promising strategy to obtain plants with a high level of non-protein thiol-containing compounds might be sulfate feeding to plants overproducing serine acetyltransferase.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

24

Warangkar, Suchita C., und Chandrahas N. Khobragade. „Purification, Characterization, and Effect of Thiol Compounds on Activity of the Erwinia carotovora L-Asparaginase“. Enzyme Research 2010 (01.11.2010): 1–10. http://dx.doi.org/10.4061/2010/165878.

Der volle Inhalt der Quelle

Annotation:

L-asparaginase was extracted from Erwinia carotovora and purified by ammonium sulfate fractionation (60–70%), Sephadex G-100, CM cellulose, and DEAE sephadex chromatography. The apparent Mr of enzyme under nondenaturing and denaturing conditions was 150 kDa and kDa, respectively. L-asparaginase activity was studied in presence of thiols, namely, L-cystine (Cys), L-methionine (Met), N-acetyl cysteine (NAC), and reduced glutathione (GSH). Kinetic parameters in presence of thiols (10–400 M) showed an increase in values (2000, 2223, 2380, 2500, and control 1666.7 moles ) and a decrease in values (0.086, 0.076, 0.062, 0.055 and control 0.098 mM) indicating nonessential mode of activation. values displayed propensity to bind thiols. A decrease in ratio in concentration plots showed inverse relationship between free thiol groups (NAC and GSH) and bound thiol group (Cys and Met). Enzyme activity was enhanced in presence of thiol protecting reagents like dithiothreitol (DTT), 2-mercaptoethanol (2-ME), and GSH, but inhibited by p-chloromercurybenzoate (PCMB) and iodoacetamide (IA).

APA, Harvard, Vancouver, ISO und andere Zitierweisen

25

Wang, Shenggang, Yue Huang und Xiangming Guan. „Fluorescent Probes for Live Cell Thiol Detection“. Molecules 26, Nr. 12 (11.06.2021): 3575. http://dx.doi.org/10.3390/molecules26123575.

Der volle Inhalt der Quelle

Annotation:

Thiols play vital and irreplaceable roles in the biological system. Abnormality of thiol levels has been linked with various diseases and biological disorders. Thiols are known to distribute unevenly and change dynamically in the biological system. Methods that can determine thiols’ concentration and distribution in live cells are in high demand. In the last two decades, fluorescent probes have emerged as a powerful tool for achieving that goal for the simplicity, high sensitivity, and capability of visualizing the analytes in live cells in a non-invasive way. They also enable the determination of intracellular distribution and dynamitic movement of thiols in the intact native environments. This review focuses on some of the major strategies/mechanisms being used for detecting GSH, Cys/Hcy, and other thiols in live cells via fluorescent probes, and how they are applied at the cellular and subcellular levels. The sensing mechanisms (for GSH and Cys/Hcy) and bio-applications of the probes are illustrated followed by a summary of probes for selectively detecting cellular and subcellular thiols.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

26

Bourgonje, Arno R., Amaal Eman Abdulle, Areej M. Al-Rawas, Muna Al-Maqbali, Mohsin Al-Saleh, Marvin B. Enriquez, Sultan Al-Siyabi et al. „Systemic Oxidative Stress Is Increased in Postmenopausal Women and Independently Associates with Homocysteine Levels“. International Journal of Molecular Sciences 21, Nr. 1 (02.01.2020): 314. http://dx.doi.org/10.3390/ijms21010314.

Der volle Inhalt der Quelle

Annotation:

Oxidative stress plays a pivotal role in the pathogenesis of cardiovascular diseases (CVD). Postmenopausal women have an increased risk of developing CVD due to decreased estrogen availability, which is accompanied by increased oxidative stress. Serum free thiols (R-SH) provide a robust and powerful read-out of systemic oxidative stress. In this study, we aimed to establish serum levels of free thiols and explore associations between free thiols and demographic, clinical, and biochemical parameters related to obesity and the risk for developing CVD in both pre- and postmenopausal women. Serum free thiols were measured in a cohort consisting of healthy pre- (n = 223) and postmenopausal (n = 118) Omani women. Postmenopausal women had significantly lower levels of serum free thiols as compared to premenopausal women (762.9 ± 85.3 vs. 780 ± 80.9 μM, age-adjusted p < 0.001). Women′s age was positively associated with serum free thiol levels in premenopausal women (β = 0.36, p = 0.002), whereas an inverse association was observed in postmenopausal women (β = −0.29, p = 0.002). Homocysteine levels were significantly inversely associated with serum free thiol levels in both pre- (β = −0.19, p = 0.005) and postmenopausal (β = −0.20, p = 0.032) women, independent from known cardiovascular risk factors. In this study, we show that postmenopausal women are affected by increased systemic oxidative stress, which independently associates with homocysteine levels.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

27

Akdogan, Muberra, Yasemin Ustundag, Arzu Akdağ, Salim Neselioglu und Ozcan Erel. „The Thiol-Disulfide Homeostasis and Coenzyme Q10 in Conjunction with Vitamin E Effect on Retinopathy Prematurity“. Open Ophthalmology Journal 13, Nr. 1 (26.03.2019): 23–28. http://dx.doi.org/10.2174/1874364101913010023.

Der volle Inhalt der Quelle

Annotation:

Purpose: This study was performed to determine whether one drop of topical administration of Coqun® (Coenzyme Q10 and Vitamin E)-a potent antioxidant-twice a day has any effect on the thiol-disulphide homeostasis-a novel oxidative stress marker in the Retinopathy Of Prematurity (ROP) disease course. Methods: This was a prospective observational study comprising 28 infants with ROP at stage 2 and higher who followed up at the paediatric intensive care unit. Ferric reducing power of plasma (FRAP), albumin, ischemia-modified albumin (IMA) and thiol disulphide homeostasis levels were studied in the infants before and two weeks after Coqun® treatment. Results: The mean gestational age was 27 (24–32) weeks, the mean birth weight was 1,012±326 g and the mean duration of care in an incubator was 64±23 days. FRAP levels were 0.91±0.17 μmol/L, IMAs were 0.85±0.29, native thiols were 248±38.9 μmol/L and total thiols were 284±39.2 μmol/L, respectively, at the beginning of therapy. FRAP levels 0.79±0.21(p= 0.006) μmol/L, IMAs 0.73±0.36(p = 0.096), native thiols 262±42.6(p = 0.164) μmol/L and total thiols 291±43.6(p = 0.344) μmol/L showed no difference after two weeks of therapy. Conclusion: Thiol disulphide homeostasis levels do not change with Coqun® therapy during ROP course.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

28

Andersson, A., A. Lindgren und B. Hultberg. „Effect of thiol oxidation and thiol export from erythrocytes on determination of redox status of homocysteine and other thiols in plasma from healthy subjects and patients with cerebral infarction“. Clinical Chemistry 41, Nr. 3 (01.03.1995): 361–66. http://dx.doi.org/10.1093/clinchem/41.3.361.

Der volle Inhalt der Quelle

Annotation:

Abstract Changes in concentration of reduced and oxidized low-M(r) thiols were measured in blood and plasma before and after the separation of blood cells. If centrifugation of blood was postponed, the reduced form of homocysteine in plasma increased with time at 22 degrees C; in contrast, the concentrations of other reduced thiols (cysteine, glutathione, and cysteinylglycine) decreased. In plasma the reduced forms of all thiols disappeared at a rate that followed first-order kinetics. The rates of disappearance ("half-lives") were temperature-dependent; they were about the same for glutathione and homocysteine (11.7 and 14.3 min, respectively, at 22 degrees C) and somewhat higher for cysteinylglycine and cysteine. After establishing proper sampling conditions for reduced thiols, we measured this thiol fraction as well as free (non-protein-bound) and total thiols in 10 reference subjects and 19 patients with cerebral infarction. Mild but significant hyperhomocysteinemia involving total and free homocysteine (but not reduced homocysteine) was found in the patients.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

29

Olson, Kenneth R., Kasey J. Clear, Yan Gao, Zhilin Ma, Nathaniel M. Cieplik, Alyssa R. Fiume, Dominic J. Gaziano et al. „Redox and Nucleophilic Reactions of Naphthoquinones with Small Thiols and Their Effects on Oxidization of H2S to Inorganic and Organic Hydropolysulfides and Thiosulfate“. International Journal of Molecular Sciences 24, Nr. 8 (19.04.2023): 7516. http://dx.doi.org/10.3390/ijms24087516.

Der volle Inhalt der Quelle

Annotation:

Naphthoquinone (1,4-NQ) and its derivatives (NQs, juglone, plumbagin, 2-methoxy-1,4-NQ, and menadione) have a variety of therapeutic applications, many of which are attributed to redox cycling and the production of reactive oxygen species (ROS). We previously demonstrated that NQs also oxidize hydrogen sulfide (H2S) to reactive sulfur species (RSS), potentially conveying identical benefits. Here we use RSS-specific fluorophores, mass spectroscopy, EPR and UV-Vis spectrometry, and oxygen-sensitive optodes to examine the effects of thiols and thiol-NQ adducts on H2S-NQ reactions. In the presence of glutathione (GSH) and cysteine (Cys), 1,4-NQ oxidizes H2S to both inorganic and organic hydroper-/hydropolysulfides (R2Sn, R=H, Cys, GSH; n = 2–4) and organic sulfoxides (GSnOH, n = 1, 2). These reactions reduce NQs and consume oxygen via a semiquinone intermediate. NQs are also reduced as they form adducts with GSH, Cys, protein thiols, and amines. Thiol, but not amine, adducts may increase or decrease H2S oxidation in reactions that are both NQ- and thiol-specific. Amine adducts also inhibit the formation of thiol adducts. These results suggest that NQs may react with endogenous thiols, including GSH, Cys, and protein Cys, and that these adducts may affect both thiol reactions as well as RSS production from H2S.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

30

Rovati, Davide, Benedetta Albini, Pietro Galinetto, Pietro Grisoli, Barbara Bassi, Piersandro Pallavicini, Giacomo Dacarro und Angelo Taglietti. „High Stability Thiol-Coated Gold Nanostars Monolayers with Photo-Thermal Antibacterial Activity and Wettability Control“. Nanomaterials 9, Nr. 9 (09.09.2019): 1288. http://dx.doi.org/10.3390/nano9091288.

Der volle Inhalt der Quelle

Annotation:

The adhesion and proliferation of bacteria on abiotic surfaces pose challenges in both health care and industrial applications. Gold nanostars (GNSs) monolayers grafted on glass have demonstrated to exert antibacterial action due to their photo-thermal features. Here, these GNS layers were further functionalized using thiols monolayers, in order to impart different wettability to the surfaces and thus adding a feature that could help to fight bacterial proliferation. Thiol that has different functional groups was used and the thiol-protected surfaces were characterized by means of UV-vis spectroscopy, contact angles, SEM and surface enhanced Raman spectroscopy (SERS). We verified that (i) coating with the proper thiol allows us to impart high hydrophilicity or hydrophobicity to the surfaces (with contact angle values ranging from 10 to 120°); (ii) GNS monolayers are strongly stabilized by functionalization with thiols, with shelf stability increasing from a few weeks to more than three months and (iii) photo-thermal features and subsequent antibacterial effects caused by hyperthermia are not changed by thiols layers, allowing us to kill at least 99.99% of representative bacterial strains.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

31

Ghosh, Tamashree, Abhishek Santra und Anup Kumar Misra. „Appel-reagent-mediated transformation of glycosyl hemiacetal derivatives into thioglycosides and glycosyl thiols“. Beilstein Journal of Organic Chemistry 9 (22.05.2013): 974–82. http://dx.doi.org/10.3762/bjoc.9.112.

Der volle Inhalt der Quelle

Annotation:

A series of glycosyl hemiacetal derivatives have been transformed into thioglycosides and glycosyl thiols in a one-pot two-step reaction sequence mediated by Appel reagent (carbon tetrabromide and triphenylphosphine). 1,2-trans-Thioglycosides and β-glycosyl thiol derivatives were stereoselectively formed by the reaction of the in situ generated glycosyl bromides with thiols and sodium carbonotrithioate. The reaction conditions are reasonably simple and yields were very good.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

32

Peddinti, Rama, und Pallavi Singh. „Waste-Free Swift Synthesis of Symmetrical and Unsymmetrical Diarylmethyl Thioethers from Diaryl Carbinols“. Synthesis 49, Nr. 16 (29.05.2017): 3633–42. http://dx.doi.org/10.1055/s-0036-1589022.

Der volle Inhalt der Quelle

Annotation:

A waste-free and swift protocol to synthesize symmetrical and unsymmetrical diarylmethyl thioethers from diaryl carbinols and thiols in good to quantitative yields is reported. The thiol scope included alkyl and aryl thiols bearing electron-donating and electron-withdrawing groups. Short reaction time, high atom economy, inexpensive activator, free from workup and aryl halides, and gram-scale synthesis are the significant features of the new protocol.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

33

Bednářová, Eva, Simona Hybelbauerová und Jindřich Jindřich. „Optimized methods for preparation of 6I-(ω-sulfanyl-alkylene-sulfanyl)-β-cyclodextrin derivatives“. Beilstein Journal of Organic Chemistry 12 (24.02.2016): 349–52. http://dx.doi.org/10.3762/bjoc.12.38.

Der volle Inhalt der Quelle

Annotation:

A general high-yielding method for the preparation of monosubstituted β-cyclodextrin derivatives which have attached a thiol group in position 6 is described. The thiol group is attached through linkers of different lengths and repeating units (ethylene glycol or methylene). The target compounds were characterized by IR, MS and NMR spectra. A simple method for their complete conversion to the corresponding disulfides as well as a method for the reduction of the disulfides back to the thiols is presented. Both, thiols and disulfides are derivatives usable for well-defined covalent attachment of cyclodextrin to gold or polydopamine-coated solid surfaces.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

34

Al-Humadi, Nabil H., Joseph KH Ma, Daniel M. Lewis, Jane YC Ma, Mark W. Barger und Paul D. Siegel. „Dose-dependent thiol and immune responses to ovalbumin challenge in Brown Norway rats“. Toxicology and Industrial Health 18, Nr. 7 (August 2002): 343–52. http://dx.doi.org/10.1191/0748233702th155oa.

Der volle Inhalt der Quelle

Annotation:

Dose-dependent specific antibody production, antigen-dependent pulmonary inflammation, and thiol changes in the lung and associated lymph nodes were examined in a Brown Norway rat model of pulmonary sensitization. Cysteine (CYSH), glutathione (GSH), and markers of inflammation in bronchoalveolar lavage fluid (BALF) were measured following ovalbumin (OVA) inhalation challenge. Alveolar macrophages (AM) and pulmonary-associated lymph node cells (LNC) were isolated and intracellular CYSH and GSH assessed. OVA-specific IgE and IgG antibodies were quantified from sera. A dose-dependent biphasic response was noted with respect to OVA-specific IgE. OVA-specific IgG concentrations were maximal at 68 mg (OVA)/m3. OVA challenge to sensitized rats induced increases in BALF albumin, total protein, lactate dehydrogenase, CYSH and GSH that were independent of serum antibody concentrations. AM thiols were modestly elevated at low OVA challenge doses, but sharply reduced at the higher OVA challenge doses. In contrast, both thiols were dose dependently elevated in BALF. CYSH, but not GSH, was elevated in LNC of OVA challenged rats. In summary, antigen exposure caused a dose-dependent alteration of inflammatory, thiol and immune parameters in OVA sensitized and challenged rats. Changes in thiol levels did not correlate with antibody responses. While the results of the present study do not support a functional role for thiols in the immune response, it is important to note the dose-dependent dramatic alteration seen in thiols following sensitization and challenge.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

35

Bramanti, Emilia, Cecilia Vecoli, Danilo Neglia, Maria Paola Pellegrini, Giorgio Raspi und Renata Barsacchi. „Speciation and Quantification of Thiols by Reversed-Phase Chromatography Coupled with On-Line Chemical Vapor Generation and Atomic Fluorescence Spectrometric Detection: Method Validation and Preliminary Application for Glutathione Measurements in Human Whole Blood“. Clinical Chemistry 51, Nr. 6 (01.06.2005): 1007–13. http://dx.doi.org/10.1373/clinchem.2004.045443.

Der volle Inhalt der Quelle

Annotation:

Abstract Background: We developed a sensitive, specific method for the low–molecular-mass thiols cysteine, cysteinylglycine, glutathione, and homocysteine and validated the method for measurement of glutathione in blood. Methods: The technique was based on reversed-phase chromatography (RPC) coupled on line with cold vapor generation atomic fluorescence spectrometry (CVGAFS). Thiols were derivatized before introduction on the column by use of a p-hydroxymercuribenzoate (PHMB) mercurial probe and separated as thiol-PHMB complexes on a Vydac C4 column. Postcolumn on-line reaction of derivatized thiols with bromine allowed rapid conversion of the thiol-PHMB complexes to inorganic mercury with recovery of 100 (2)% of the sample. HgII was selectively detected by atomic fluorescence spectrometry in an Ar/H2 miniaturized flame after sodium borohydride reduction to Hg0. Results: The relationship between thiol-PHMB complex concentration and peak area (CVGAFS signal) was linear over the concentration range 0.01–1400 μmol/L (injected). The detection limits were 1, 1, 0.6, and 0.8 nmol/L for cysteine, cysteinylglycine, homocysteine, and glutathione in the injected sample, respectively. The CVs for thiols were 1.5%–2.2% for calibrator solutions and 2.1% and 3.0% for real samples. The RPC-CVGAFS method allowed speciation of glutathione (reduced and oxidized) in human whole blood from healthy donors and from the coronary sinus of patients with idiopathic dilated cardiomyopathy during and after chronotropic stress. Conclusion: The RPC-CVGAFS method could be used to measure reduced and oxidized glutathione in human whole blood as disease biomarkers.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

36

Pellom, Samuel, Ryan Michalek und Jason Grayson. „Regulation of Surface Free Thiol Levels During CD8+ T Cell Activation, Proliferation and Differentiation (132.7)“. Journal of Immunology 184, Nr. 1_Supplement (01.04.2010): 132.7. http://dx.doi.org/10.4049/jimmunol.184.supp.132.7.

Der volle Inhalt der Quelle

Annotation:

Abstract Upon both B and T cell activation the level of reactive oxygen intermediates (ROI) increases. Prior studies in the literature demonstrated that activated lymphocytes have increased total levels of surface free thiols, potentially as a compensatory mechanism to prevent surface oxidation. In this study, we determined how surface free thiol levels were regulated during the activation, proliferation, and differentiation of naïve CD8+ T cells both in vitro and in vivo. In vitro, we found that the levels of surface free thiols increased within 24 hours regardless of the activation stimulus and were maintained for at least three divisions. To understand how levels were modulated in vivo, we examined antigen-specific CD8+ T cells using lymphocytic choriomeningitis virus (LCMV) infection of mice and MHC Class I tetramers. On day 5 postinfection, the levels of surface free thiols were 8-fold higher on effector cells compared to those found on naïve CD8+ T cells. By day 8 postinfection this had decreased to 4-fold. After the infection was cleared, memory CD8+ T cells had 1.5-fold higher levels of surface free thiols than naïve cells. This contrasted with the results during chronic LCMV-Clone 13 infection. On day 8 postinfection surface free thiol levels were 11-fold higher and remained elevated until day 35 postinfection. These results suggest that surface free thiol levels are elevated most highly in rapidly proliferating cells and do not correlate with lymphocyte function.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

37

Martínez-Blanco, Gilberto Josué, und Jannu Casanova-Moreno. „Characterization of the Reductive Desorption of Self-Assembled Monolayers on Platinum Surfaces“. ECS Meeting Abstracts MA2022-01, Nr. 45 (07.07.2022): 1936. http://dx.doi.org/10.1149/ma2022-01451936mtgabs.

Der volle Inhalt der Quelle

Annotation:

Thiol-based self-assembled monolayers (SAMs) have been widely characterized on gold surfaces, with the desorption potentials of these SAMs being of special interest for nanotechnology and biological applications. However, the study and determination of desorption potentials of thiol SAMs on platinum surfaces has been limited by the hydrogen evolution reaction (HER) catalyzed by the metal, which dominates response signals when studying the system through conventional electrochemical techniques. Through the coupling of electrochemical techniques with fluorescence microscopy, the problem of the HER signal can be avoided in the study of desorption potentials for the platinum-thiol monolayer systems. By using fluorescent thiols, as well as monocrystalline platinum spheres, the desorption potential for different crystallographic orientations and thiol length combinations can be determined. The results obtained show that the desorption of Bodipy C10SH thiols from platinum surfaces occur at more positive potentials in [111] crystallographic orientations, and at more negative potentials at [100] ones. On the other hand, no notable difference was found in the desorption order of Bodipy C16SH from these two orientations. However, the use of fluorescence microscopy for the solution of this problem poses other challenges: the time the thiols need to separate enough from the metallic substrate to not be affected by quenching, as well as the facts that thiols fluoresce less as they dilute and the existing spectral overlap for the molecules, adds difficulties to the establishment of the desorption potentials. Through COMSOL Multiphysics simulations, we try to simulate the systems hereby proposed of platinum with thiol-based SAMs. Using them, the desorption potentials, as well as the monolayer coverage under specific conditions, can be determined. We expect that, with further development of the model, more specific values for these variables can be determined. Figure 1

APA, Harvard, Vancouver, ISO und andere Zitierweisen

38

Georgescu, Simona Roxana, Cristina Iulia Mitran, Madalina Irina Mitran, Clara Matei, Gabriela Loredana Popa, Ozcan Erel und Mircea Tampa. „Thiol-Disulfide Homeostasis in Skin Diseases“. Journal of Clinical Medicine 11, Nr. 6 (09.03.2022): 1507. http://dx.doi.org/10.3390/jcm11061507.

Der volle Inhalt der Quelle

Annotation:

Oxidative stress represents the imbalance between oxidants and antioxidants and has been associated with a wide range of diseases. Thiols are the most important compounds in antioxidant defense. There is an equilibrium between thiols and their oxidized forms, disulfides, known as dynamic thiol-disulfide homeostasis (TDH). In 2014, Erel and Neselioglu developed a novel automated assay to measure thiol and disulfide levels. Subsequently, many researchers have used this simple, inexpensive and fast method for evaluating TDH in various disorders. We have reviewed the literature on the role of TDH in skin diseases. We identified 26 studies that evaluated TDH in inflammatory diseases (psoriasis, seborrheic dermatitis, atopic dermatitis, vitiligo, acne vulgaris and rosacea), allergic diseases (acute and chronic urticaria) and infectious diseases (warts, pityriasis rosea and tinea versicolor). The results are heterogeneous, but in most cases indicate changes in TDH that shifted toward disulfides or toward thiols, depending on the extent of oxidative damage.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

39

Sen, Chandan K. „Update on Thiol Status and Supplements in Physical Exercise“. Canadian Journal of Applied Physiology 26, S1 (Oktober 2001): S4—S12. http://dx.doi.org/10.1139/h2001-037.

Der volle Inhalt der Quelle

Annotation:

Strenuous physical exercise represents a condition that is often associated with increased production of reactive oxygen species in various tissues. One of the most reliable indices of exercise-induced oxidant production is tissue glutathione oxidation. In humans, exerciseinduced blood glutathione oxidation is rapid and subject to control by antioxidant supplementation. The objective of this brief review is to provide an update of our current understanding of cellular thiols and thiol antioxidants. Cellular thiols are critically important in maintaining the cellular antioxidant defense network. In addition, thiols play a key role in regulating redox-sensitive signal transduction process. Lipoic acid is a highly promising thiol antioxidant supplement. Recent studies have clarified that while higher levels of oxidants may indeed inflict oxidative damage, oxidants are not necessarily deleterious. Under certain conditions oxidants may function as cellular messengers that regulate a multitude of signal transduction pathways. In light of this, the significance of oxidants in various aspects of biology needs to be revisited.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

40

Tong, Ka-Chung, Chun-Nam Lok, Pui-Ki Wan, Di Hu, Yi Man Eva Fung, Xiao-Yong Chang, Song Huang, Haibo Jiang und Chi-Ming Che. „An anticancer gold(III)-activated porphyrin scaffold that covalently modifies protein cysteine thiols“. Proceedings of the National Academy of Sciences 117, Nr. 3 (02.01.2020): 1321–29. http://dx.doi.org/10.1073/pnas.1915202117.

Der volle Inhalt der Quelle

Annotation:

Cysteine thiols of many cancer-associated proteins are attractive targets of anticancer agents. Herein, we unequivocally demonstrate a distinct thiol-targeting property of gold(III) mesoporphyrin IX dimethyl ester (AuMesoIX) and its anticancer activities. While the binding of cysteine thiols with metal complexes usually occurs via M–S bond formation, AuMesoIX is unique in that the meso-carbon atom of the porphyrin ring is activated by the gold(III) ion to undergo nucleophilic aromatic substitution with thiols. AuMesoIX was shown to modify reactive cysteine residues and inhibit the activities of anticancer protein targets including thioredoxin, peroxiredoxin, and deubiquitinases. Treatment of cancer cells with AuMesoIX resulted in the formation of gold-bound sulfur-rich protein aggregates, oxidative stress-mediated cytotoxicity, and accumulation of ubiquitinated proteins. Importantly, AuMesoIX exhibited effective antitumor activity in mice. Our study has uncovered a gold(III)-induced ligand scaffold reactivity for thiol targeting that can be exploited for anticancer applications.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

41

Akinloye, D. I., R. N. Ugbaja, A. J. Akamo, M. A. Toriola, A. O. Adewale, E. I. Ugwor und A. S. James. „Effects of alcohol-graded concentrations on total thiols and some thiol utilizing enzymes“. Bayero Journal of Pure and Applied Sciences 15, Nr. 1 (09.12.2022): 202–9. http://dx.doi.org/10.4314/bajopas.v15i1.29.

Der volle Inhalt der Quelle

Annotation:

Excessive intake of alcohol has been documented to initiate different pathological conditions. Although various researchers have reported these associations, the modulatory effects on endogenous thiols are not well studied. This study investigated the effects of alcohol-graded concentrations on some thiol utilizing enzymes in rats. Adults’ male rats were divided into four main groups and treated with distilled water, 30 %, 40 % and 50 % alcohol (3.20 g / Kg body weight). Five rats from each group were sacrificed at the end of 1, 7, 14, 21, and 28 day(s) of the experiment. Assay of glutathione peroxidase and glutathione S-transferase specific activities along with total thiols levels were carried out. Alcohol administration resulted in an upregulation of the activities of glutathione peroxidase and glutathione S-transferase with concomitant depletion of total thiols concentrations. Conclusively, this study affirms that graded dosages of alcohol administration to rats induced perturbations in the thiol utilizing system in a non-time dependent consistent manner.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

42

Wessig, Pablo, Tanja Schulze, Alexandra Pfennig, Steffen M. Weidner, Sascha Prentzel und Helmut Schlaad. „Thiol–ene polymerization of oligospiroketal rods“. Polymer Chemistry 8, Nr. 44 (2017): 6879–85. http://dx.doi.org/10.1039/c7py01569k.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

43

Rawat, Mamta, und Julie A. Maupin-Furlow. „Redox and Thiols in Archaea“. Antioxidants 9, Nr. 5 (05.05.2020): 381. http://dx.doi.org/10.3390/antiox9050381.

Der volle Inhalt der Quelle

Annotation:

Low molecular weight (LMW) thiols have many functions in bacteria and eukarya, ranging from redox homeostasis to acting as cofactors in numerous reactions, including detoxification of xenobiotic compounds. The LMW thiol, glutathione (GSH), is found in eukaryotes and many species of bacteria. Analogues of GSH include the structurally different LMW thiols: bacillithiol, mycothiol, ergothioneine, and coenzyme A. Many advances have been made in understanding the diverse and multiple functions of GSH and GSH analogues in bacteria but much less is known about distribution and functions of GSH and its analogues in archaea, which constitute the third domain of life, occupying many niches, including those in extreme environments. Archaea are able to use many energy sources and have many unique metabolic reactions and as a result are major contributors to geochemical cycles. As LMW thiols are major players in cells, this review explores the distribution of thiols and their biochemistry in archaea.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

44

Jain, Surbhi, Lori W. McGinnes und Trudy G. Morrison. „Overexpression of Thiol/Disulfide Isomerases Enhances Membrane Fusion Directed by the Newcastle Disease Virus Fusion Protein“. Journal of Virology 82, Nr. 24 (01.10.2008): 12039–48. http://dx.doi.org/10.1128/jvi.01406-08.

Der volle Inhalt der Quelle

Annotation:

ABSTRACT Newcastle disease virus (NDV) fusion (F) protein directs membrane fusion, which is required for virus entry and cell-cell fusion. We have previously shown that free thiols are present in cell surface-expressed NDV F protein and that blocking the production of free thiols by thiol-disulfide exchange inhibitors inhibited the membrane fusion mediated by F protein (J Virol. 81:2328-2339, 2007). Extending these observations, we evaluated the role of the overexpression of two disulfide bond isomerases, protein disulfide isomerase (PDI) and ERdj5, in cell-cell fusion mediated by NDV glycoproteins. The overexpression of these isomerases resulted in significantly increased membrane fusion, as measured by syncytium formation and content mixing. The overexpression of these isomerases enhanced the production of free thiols in F protein when expressed without hemagglutination-neuraminidase (HN) protein but decreased free thiols in F protein expressed with HN protein. By evaluating the binding of conformation-sensitive antibodies, we found that the overexpression of these isomerases favored a postfusion conformation of surface-expressed F protein in the presence of HN protein. These results suggest that isomerases belonging to the PDI family catalyze the production of free thiols in F protein, and free thiols in F protein facilitate membrane fusion mediated by F protein.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

45

van Eijk, Larissa E., Adriana Tami, Jan-Luuk Hillebrands, Wilfred F. A. den Dunnen, Martin H. de Borst, Peter H. J. van der Voort, Marian L. C. Bulthuis et al. „Mild Coronavirus Disease 2019 (COVID-19) Is Marked by Systemic Oxidative Stress: A Pilot Study“. Antioxidants 10, Nr. 12 (20.12.2021): 2022. http://dx.doi.org/10.3390/antiox10122022.

Der volle Inhalt der Quelle

Annotation:

Oxidative stress has been implicated to play a critical role in the pathophysiology of coronavirus disease 2019 (COVID-19) and may therefore be considered as a relevant therapeutic target. Serum free thiols (R-SH, sulfhydryl groups) comprise a robust marker of systemic oxidative stress, since they are readily oxidized by reactive oxygen species (ROS). In this study, serum free thiol concentrations were measured in hospitalized and non-hospitalized patients with COVID-19 and healthy controls and their associations with relevant clinical parameters were examined. Serum free thiol concentrations were measured colorimetrically (Ellman’s method) in 29 non-hospitalized COVID-19 subjects and 30 age-, sex-, and body-mass index (BMI)-matched healthy controls and analyzed for associations with clinical and biochemical disease parameters. Additional free thiol measurements were performed on seven serum samples from COVID-19 subjects who required hospitalization to examine their correlation with disease severity. Non-hospitalized subjects with COVID-19 had significantly lower concentrations of serum free thiols compared to healthy controls (p = 0.014), indicating oxidative stress. Serum free thiols were positively associated with albumin (St. β = 0.710, p < 0.001) and inversely associated with CRP (St. β = −0.434, p = 0.027), and showed significant discriminative ability to differentiate subjects with COVID-19 from healthy controls (AUC = 0.69, p = 0.011), which was slightly higher than the discriminative performance of CRP concentrations regarding COVID-19 diagnosis (AUC = 0.66, p = 0.042). This study concludes that systemic oxidative stress is increased in patients with COVID-19 compared with healthy controls. This opens an avenue of treatment options since free thiols are amenable to therapeutic modulation.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

46

Bourgonje, Arno R., Ruben Y. Gabriëls, Martin H. de Borst, Marian L. C. Bulthuis, Klaas Nico Faber, Harry van Goor und Gerard Dijkstra. „Serum Free Thiols Are Superior to Fecal Calprotectin in Reflecting Endoscopic Disease Activity in Inflammatory Bowel Disease“. Antioxidants 8, Nr. 9 (01.09.2019): 351. http://dx.doi.org/10.3390/antiox8090351.

Der volle Inhalt der Quelle

Annotation:

Oxidative stress plays a pivotal role in the pathogenesis of inflammatory bowel diseases (IBD). Serum free thiols (R-SH) reliably reflect systemic oxidative stress, since they are readily oxidized by reactive species. Here, we aimed to establish concentrations of serum free thiols in IBD and assessed their discriminating capacity regarding endoscopic disease activity. Albumin-adjusted serum free thiol concentrations were measured in 78 IBD patients (31 Crohn’s disease (CD) and 47 ulcerative colitis (UC) patients) and 50 healthy controls and analyzed for associations with disease parameters and their discriminative value regarding endoscopic disease activity (n = 54) or fecal calprotectin (n = 36) in patients for which those data were available. Mean serum free thiol concentrations were significantly lower in both CD and UC as compared to healthy controls (19.4 ± 3.1 and 17.8 ± 3.4 vs. 21.1 ± 1.9 µmol/g albumin, P < 0.001). Free thiols highly accurately discriminated between mild and moderate-to-severe disease activity, better than fecal calprotectin (FC) levels (AUC = 0.87, P < 0.001 vs. AUC = 0.76, P < 0.05, respectively) and this was maintained after cross-validation (AUC = 0.89, P < 0.001). Serum free thiols are reduced in IBD as compared to healthy controls and strongly correlate with the degree of endoscopic disease activity. Quantifying systemic redox status in IBD may be a promising, minimally invasive strategy to monitor IBD disease activity.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

47

Shatalin, Yuri V., Victoria S. Shubina, Marina E. Solovieva und Vladimir S. Akatov. „Differences in the Formation of Reactive Oxygen Species and Their Cytotoxicity between Thiols Combined with Aqua- and Cyanocobalamins“. International Journal of Molecular Sciences 23, Nr. 19 (20.09.2022): 11032. http://dx.doi.org/10.3390/ijms231911032.

Der volle Inhalt der Quelle

Annotation:

Cobalamin is an essential nutrient required for the normal functioning of cells. Its deficiency can lead to various pathological states. Hydroxocobalamin (HOCbl) and cyanocobalamin (CNCbl) are the forms of vitamin B12 that are most commonly used for supplementation. There is substantial evidence indicating that cobalamins can both suppress and promote oxidative stress; however, the mechanisms underlying these effects are poorly understood. Here, it was shown that the oxidation of thiols catalyzed by HOCbl and CNCbl is accompanied by reactive oxygen species (ROS) production and induces, under certain conditions, oxidative stress and cell death. The form of vitamin B12 and the structure of thiol play a decisive role in these processes. It was found that the mechanisms and kinetics of thiol oxidation catalyzed by HOCbl and CNCbl differ substantially. HOCbl increased the rate of oxidation of thiols to a greater extent than CNCbl, but quenched ROS in combination with certain thiols. Oxidation catalyzed by CNCbl was generally slower. Yet, the absence of ROS quenching resulted in their higher accumulation. The aforementioned results might explain a more pronounced cytotoxicity induced by combinations of thiols with CNCbl. On the whole, the data obtained provide a new insight into the redox processes in which cobalamins are involved. Our results might also be helpful in developing new approaches to the treatment of some cobalamin-responsive disorders in which oxidative stress is an important component.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

48

Cobley, James Nathan, und Holger Husi. „Immunological Techniques to Assess Protein Thiol Redox State: Opportunities, Challenges and Solutions“. Antioxidants 9, Nr. 4 (15.04.2020): 315. http://dx.doi.org/10.3390/antiox9040315.

Der volle Inhalt der Quelle

Annotation:

To understand oxidative stress, antioxidant defense, and redox signaling in health and disease it is essential to assess protein thiol redox state. Protein thiol redox state is seldom assessed immunologically because of the inability to distinguish reduced and reversibly oxidized thiols by Western blotting. An underappreciated opportunity exists to use Click PEGylation to realize the transformative power of simple, time and cost-efficient immunological techniques. Click PEGylation harnesses selective, bio-orthogonal Click chemistry to separate reduced and reversibly oxidized thiols by selectively ligating a low molecular weight polyethylene glycol moiety to the redox state of interest. The resultant ability to disambiguate reduced and reversibly oxidized species by Western blotting enables Click PEGylation to assess protein thiol redox state. In the present review, to enable investigators to effectively harness immunological techniques to assess protein thiol redox state we critique the chemistry, promise and challenges of Click PEGylation.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

49

Nielsen, Marie B., Bente Jespersen, Henrik Birn, Nicoline V. Krogstrup, Arno R. Bourgonje, Henri G. D. Leuvenink, Harry van Goor und Rikke Nørregaard. „Elevated plasma free thiols are associated with early and one-year graft function in renal transplant recipients“. PLOS ONE 16, Nr. 8 (11.08.2021): e0255930. http://dx.doi.org/10.1371/journal.pone.0255930.

Der volle Inhalt der Quelle

Annotation:

Background Reduced free thiols in plasma are indicative of oxidative stress, which is an important contributor to ischaemia-reperfusion injury (IRI) in kidney transplantation leading to kidney damage and possibly delayed graft function (DGF). In a post-hoc, exploratory analysis of the randomised controlled CONTEXT trial, we investigated whether higher (i.e. less oxidised) plasma levels of free thiols as a biomarker of reduced oxidative stress are associated with a better initial graft function or a higher GFR. Methods Free thiol levels were measured in plasma at baseline, 30 and 90 minutes after reperfusion of the kidney as well as at Day 1, Day 5 and twelve months after kidney transplantation in 217 patients from the CONTEXT study. Free thiol levels were compared to the kidney graft function measured as the estimated time to a 50% reduction in plasma creatinine (tCr50), the risk of DGF and measured GFR (mGFR) at Day 5 and twelve months after transplantation. Results Higher levels of free thiols at Day 1 and Day 5 are associated with higher mGFR at Day 5 (p<0.001, r2adj. = 0.16; p<0.001, r2adj. = 0.25), as well as with mGFR at twelve months (p<0.001, r2adj. = 0.20; p<0.001, r2adj. = 0.16). However, plasma levels of free thiols at 30 minutes and 90 minutes, but not Day 1, were significantly higher among patients experiencing DGF. Conclusion Higher levels of plasma free thiols at Day 1 and Day 5, which are reflective of lower levels of oxidative stress, are associated with better early and late graft function in recipients of a kidney graft from deceased donors. Trial registration ClinicalTrials.gov Identifier: NCT01395719.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

50

Sun, Jinyu, Liangwei Zhang, Xiaolong Zhang, Yuesong Hu, Chunpo Ge und Jianguo Fang. „An ultrafast turn-on thiol probe for protein labeling and bioimaging“. Analyst 141, Nr. 6 (2016): 2009–15. http://dx.doi.org/10.1039/c5an02347e.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

Zeitschriftenartikel zum Thema „Thiols“

Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an