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1
Veksler, Kirill V., and Evgenia N. Volkov. "HYDROPHOBIC AROMATIC THIO (DITHIO) COMPOUNDS AS CHROMOGENIC ANALYTICAL REAGENTS FOR PHOTOMETRIC DETERMINATION OF THIOLS BY MERCAPTO GROUP III. ANALYTICAL REAGENTS IN WATER-MICELLAR SOLUTIONS OF CATIONIC SURFACTANTS." Bulletin of the Saint Petersburg State Institute of Technology (Technical University) 67 (2023): 53–58. http://dx.doi.org/10.36807/1998-9849-2023-67-93-53-58.
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It was discovered for the first time the ability of a number of hydrophobic aromatic azothio (dithio) compounds, chromogenic analytical reagents to the mercapto group in dipolar aprotic solvents (SH- reagents), to react in aqueous solutions of cationic surfactants with sulfhydryl compounds (SH- compounds) by the type of "thiol-thiol" substitution with manifestation of significant analytical effects (AE). Photometry of hydrophobic thiols is possible by preliminary extraction of the latter with a solution of the SH- reagent from a solution in an acyclic ultimate hydrocarbon. The "thiol-thiol" substitution products may be extracted from aqueous solutions of cationic surfactants with chloroform followed by photometry of AE in an organic medium; reducing the volume of the organic phase compared to the aqueous phase results in higher sensitivity of the assay. Appropriate analytical methods can be used to control hydrogen sulfide and thiols in natural and industrial wastewater, in hydrocarbon gases, and in biological fluids.
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Perea, Ana, José Ignacio Manzano, Yasuhisa Kimura, Kazumitsu Ueda, Santiago Castanys, and Francisco Gamarro. "Leishmania LABCG2 transporter is involved in ATP-dependent transport of thiols." Biochemical Journal 475, no. 1 (2018): 87–97. http://dx.doi.org/10.1042/bcj20170685.
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The Leishmania LABCG2 transporter has a key role in the redox metabolism of these protozoan parasites. Recently, the involvement of LABCG2 in virulence, autophagy and oxidative stress has been described. Null mutant parasites for LABCG2 present an increase in the intracellular levels of glutathione (GSH) and trypanothione [T(SH)2]. On the other hand, parasites overexpressing LABCG2 transporter export non-protein thiols to the extracellular medium. To explore if LABCG2 may mediate an active transport of non-protein thiols, the effect of these molecules on ATPase activity of LABCG2 as well as the ability of LABCG2 to transport them was determined using a baculovirus-Sf9 insect cell system. Our results indicate that all thiols tested [GSH, T(SH)2] as well as their oxidized forms GSSG and TS2 (trypanothione disulfide) stimulate LABCG2-ATPase basal activity. We have measured the transport of [3H]-GSH in inside-out Sf9 cell membrane vesicles expressing LABCG2-GFP (green fluorescence protein), finding that LABCG2 was able to mediate a rapid and concentration-dependent uptake of [3H]-GSH in the presence of ATP. Finally, we have analyzed the ability of different thiol species to compete for this uptake, T(SH)2 and TS2 being the best competitors. The IC50 value for [3H]-GSH uptake in the presence of increasing concentrations of T(SH)2 was less than 100 μM, highlighting the affinity of this thiol for LABCG2. These results provide the first direct evidence that LABCG2 is an ABC transporter of reduced and oxidized non-protein thiols in Leishmania, suggesting that this transporter can play a role in the redox metabolism and related processes in this protozoan parasite.
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Razygraev, A. V., K. I. Taborskaya, M. A. Petrosyan, and Zh N. Tumasova. "Thiol peroxidase activities in rat blood plasma determined with hydrogen peroxide and 5,5`-dithio-bis(2-nitrobenzoic acid)." Biomeditsinskaya Khimiya 62, no. 4 (2016): 431–38. http://dx.doi.org/10.18097/pbmc20166204431.
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Earlier it has been shown that extracellular glutathione peroxidase (GPx3) from human plasma is able to use cysteine (Cys-SH) instead of glutathione (GSH) as a thiol substrate. In the present study, the ability of rat plasma to utilize not only GSH, but also Cys-SH and homocysteine (Hcy-SH), in the thiol peroxidase reaction has been confirmed. The molar ratio between thiol and H2O2 in the catalyzed reaction was 2:1. The specific activity increased with fractionation of proteins. At a fixed thiol concentration of 0.23 mM, the saturation by H2O2 with vmax app of 100, 128, and 132 nmol H2O2 / s per 1 ml of plasma was found for DL-Cys-SH, L-GSH, and DL-Hcy-SH, respectively. Rank distributions of activities towards all three thiol substrates within plasma protein fractions are fully identical (the probability of random full coincidence was less than 0.01). The statistical analysis confirms that Cys-SH peroxidase, Hcy-SH peroxidase, and GSH peroxidase activities are closely associated with each other. The most probable outcome of this result is the ability of rat GPx3 to utilize all three thiols as substrates for oxidation. Probably, thiol peroxidase is a participant of formation of plasma cystine (Cys-SS-Cys) from Cys-SH in plasma. If the forms of Hcy exhibit different toxic effects, it can be suggested that thiol peroxidase regulates Hcy toxicity in hyperhomocysteinemia through Hcy-SH oxidation to homocystine (Hcy-SS-Hcy).
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Ozyurt, Songul, Neslihan Ozcelik, Bilge Yilmaz Kara, et al. "Evaluation of Thiol/Disulfide Homeostasis in Bronchiectasis." Canadian Respiratory Journal 2022 (January 29, 2022): 1–6. http://dx.doi.org/10.1155/2022/8340450.
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Purpose. Thiols are sulfhydryl-containing organic compounds that have an important role in preventing cellular oxidative stress. This study compares the blood oxidative stress marker levels in bronchiectasis cases during their stable periods with healthy controls. Materials and Methods. Seventy-seven patients (49 patients with stable bronchiectasis/28 healthy controls), followed up by the chest disease clinic, were included in the study. Peripheral blood thiol-disulfide parameters (NT: native thiol (−SH); TT: total thiol (−SH + SS); SS: disulfide (−SS); SS-SH: disulfide/native thiol index; SS-TT: disulphide/total thiol index; SH-TT: native thiol/total thiol index), and ischemia-modified albumin (IMA) levels were examined in the stable bronchiectasis group and the control group. Thiol-disulfide homeostasis was evaluated using a novel and automated assay. Findings and Result. Blood native thiol levels in patients with stable bronchiectasis were found to be significantly higher compared with healthy controls. A positive correlation between the total airway disease score and IMA levels was present. Our findings revealed that native thiol levels, which constitute a part of the antioxidant defense system, are increased in patients with stable bronchiectasis.
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Sato, N., S. Iwata, K. Nakamura, T. Hori, K. Mori, and J. Yodoi. "Thiol-mediated redox regulation of apoptosis. Possible roles of cellular thiols other than glutathione in T cell apoptosis." Journal of Immunology 154, no. 7 (1995): 3194–203. http://dx.doi.org/10.4049/jimmunol.154.7.3194.
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Abstract Thiol redox status modulates various aspects of cellular function. We demonstrate that oxidation of cellular sulfhydryl (SH) groups induces apoptosis. In Jurkat T cells and human PBL blasts, the fraction of apoptotic nuclei increased after treatment with an SH-specific oxidant, diamide. Analysis of DNA fragmentation and nuclear morphology also indicated that SH oxidation could induce apoptosis. In the apoptosis induced by SH oxidation, the decrease of cellular glutathione was transient and the increase of glutathione disulfide was observed only after apoptotic changes had occurred. Depletion of cellular glutathione with buthionine sulfoximine failed to induce apoptosis, despite a marked decrease of cellular glutathione, which was greater than that observed in apoptosis induced by diamide. Thus, the changes of cellular glutathione or glutathione disulfide may not be the major cause of apoptosis induced by diamide. Intracellular adult T cell leukemia-derived factor/human thioredoxin, another thiol-related antioxidant protein, was oxidized by incubation with diamide. These results suggest that thiol redox status is one of the key factors of the apoptotic pathway in which thiols other than glutathione may play even more critical roles.
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Suvarli, Narmin, Iris Perner-Nochta, Jürgen Hubbuch, and Michael Wörner. "Thiol-Functional Polymer Nanoparticles via Aerosol Photopolymerization." Polymers 13, no. 24 (2021): 4363. http://dx.doi.org/10.3390/polym13244363.
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Spherical, individual polymer nanoparticles with functional –SH groups were synthesized via aerosol photopolymerization (APP) employing radically initiated thiol-ene chemistry. A series of various thiol and alkene monomer combinations were investigated based on di-, tri-, and tetrafunctional thiols with difunctional allyl and vinyl ethers, and di- and trifunctional acrylates. Only thiol and alkene monomer combinations able to build cross-linked poly(thio-ether) networks were compatible with APP, which requires fast polymerization of the generated droplet aerosol during the photoreactor passage within a residence time of half-minute. Higher monomer functionalities and equal overall stoichiometry of functional groups resulted in the best nanoparticles being spherical and individual, proven by scanning electron microscopy (SEM). The presence of reactive –SH groups in the synthesized nanoparticles as a basis for post-polymerization modifications was verified by Ellman’s test.
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Boekhoud, Lisanne, Jacqueline Koeze, Elisabeth C. van der Slikke, et al. "Acute Kidney Injury is Associated with Lowered Plasma-Free Thiol Levels." Antioxidants 9, no. 11 (2020): 1135. http://dx.doi.org/10.3390/antiox9111135.
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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.
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Bourgonje, Arno R., Amaal Eman Abdulle, Areej M. Al-Rawas, et al. "Systemic Oxidative Stress Is Increased in Postmenopausal Women and Independently Associates with Homocysteine Levels." International Journal of Molecular Sciences 21, no. 1 (2020): 314. http://dx.doi.org/10.3390/ijms21010314.
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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.
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van Dijk, Peter R., Andreas Pasch, Sonja L. van Ockenburg-Brunet, et al. "Thiols as markers of redox status in type 1 diabetes mellitus." Therapeutic Advances in Endocrinology and Metabolism 11 (January 2020): 204201882090364. http://dx.doi.org/10.1177/2042018820903641.
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Introduction: Type 1 diabetes mellitus (T1DM) is associated with inflammation and the production of reactive oxygen species (ROS). Systemically, free thiols (R-SH) can be oxidized by ROS and circulating R-SH concentrations may directly reflect the systemic redox status. In this study the association between R-SH and clinical parameters of T1DM, including glycated haemoglobin A1c (HbA1c), was investigated. This is of particular interest since thiols are amendable to therapeutic intervention. Methods: As part of a prospective cohort study, data from 216 patients with a mean age of 45 (12) years, 57% male, diabetes duration 22 (16, 30) years and HbA1c of 60 (11) mmol/mol were examined. Baseline data were collected in 2002 and follow-up data in 2018. Cox proportional hazards regression analysis, with age, sex, HbA1c and R-SH, was used to assess prognostic factors for the development of complications. Results: At baseline, the plasma concentration of R-SH was 281.8 ± 34.0 μM. In addition to a lower concentration of NT-proBNP in the highest R-SH quartile (305–379 µM) there were no differences in baseline characteristics between the quartiles of R-SH. The Pearson correlation coefficient for R-SH and NT-proBNP was −0.290 ( p < 0.001). No significant correlation between R-SH and baseline HbA1c ( r = −0.024, p = 0.726) was present. During follow-up, 42 macrovascular and 92 microvascular complications occurred. In Cox regression, R-SH was not a prognostic factor for the development of microvascular [hazard ratio (HR) 0.999 (95% confidence interval (CI) 0.993, 1.005)] and macrovascular [HR 0.993 (95% CI 0.984, 1.002)] complications. Conclusions: In addition to a negative association with NT-proBNP, no relevant relationships between R-SH and parameters of T1DM, including HbA1c, were present in this study.
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Bourgonje, Arno R., Ruben Y. Gabriëls, Martin H. de Borst, et al. "Serum Free Thiols Are Superior to Fecal Calprotectin in Reflecting Endoscopic Disease Activity in Inflammatory Bowel Disease." Antioxidants 8, no. 9 (2019): 351. http://dx.doi.org/10.3390/antiox8090351.
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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.
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van Eijk, Larissa E., Adriana Tami, Jan-Luuk Hillebrands, et al. "Mild Coronavirus Disease 2019 (COVID-19) Is Marked by Systemic Oxidative Stress: A Pilot Study." Antioxidants 10, no. 12 (2021): 2022. http://dx.doi.org/10.3390/antiox10122022.
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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.
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Calhoun, M. C., B. C. Baldwin, S. W. Kuhlmann, and H. L. Kim. "Experimental prevention of bitterweed (Hymenoxys odorata) poisoning of sheep." American Journal of Veterinary Research 50, no. 9 (1989): 1642–46. https://doi.org/10.2460/ajvr.1989.50.09.1642.
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SUMMARY To examine the effects on bitterweed toxicity of dietary factors known to increase thiol concentrations in the body, 36 lambs were fed one of the following diets (12 lambs/diet) for a minimum of 9 days prior to bitterweed administration: diet 1, 10% crude protein; diet 2, 20% crude protein, 0.5% methionine, 0.5% sodium sulfate, and 1,102 IU of vitamin E/kg; and diet 3, diet 2 with 0.5% ethoxyquin hydrochloride added. Four lambs fed each diet were euthanatized prior to bitterweed administration (initial euthanasia group). Four lambs fed each diet were administered bitterweed (0.68% hymenoxon, air-dried basis) at a rate of 0.25% of live weight for 5 consecutive days. The remaining four lambs on each diet served as unchallenged controls. In the initial euthanasia group, diet 2 increased extracellular blood thiol concentrations (1.12 vs 0.94 mg of sh/dl, P < 0.10), rumen fluid thiol concentrations (4.46 vs 1.88 mg of sh/dl, P < 0.05), and liver thiol concentrations (263.6 vs 109.3 μg sh/g of wet wt, P < 0.05), compared with diet 1. Ethoxyquin hydrochloride (diet 3) reduced blood thiol concentrations (0.94 vs 1.12 mg of sh/dl, P < 0.10) and liver thiol concentrations (151.6 vs 263.6 μg of sh/g of wet wt, P < 0.05), compared with diet 2. Kidney thiols were unaffected by treatments. In lambs fed diet 1, bitterweed increased serum creatinine (P < 0.05) and urea nitrogen (P < 0.10) concentrations and γ-glutamyltransferase (P < 0.05) and aspartate transaminase (P < 0.05) activities; whereas, only serum creatinine (P < 0.05) and urea nitrogen (P < 0.05) concentrations were increased by bitterweed in lambs fed diet 2 and none of these serum constituents were increased by bitterweed in lambs fed diet 3. These results demonstrate that dietary components that increase thiol concentrations protect against bitterweed poisoning. However, this does not appear to explain the additional benefit from including ethoxyquin hydrochloride in the diet.
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Zheng, Yuanyuan, Wenrui Zheng, Danfeng Zhu, and Huifang Chang. "Theoretical modeling of pKa's of thiol compounds in aqueous solution." New Journal of Chemistry 43, no. 13 (2019): 5239–54. http://dx.doi.org/10.1039/c8nj06259e.
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Sytykiewicz, Hubert, Iwona Łukasik, Sylwia Goławska, and Grzegorz Chrzanowski. "Aphid-Triggered Changes in Oxidative Damage Markers of Nucleic Acids, Proteins, and Lipids in Maize (Zea mays L.) Seedlings." International Journal of Molecular Sciences 20, no. 15 (2019): 3742. http://dx.doi.org/10.3390/ijms20153742.
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Prior experiments illustrated reactive oxygen species (ROS) overproduction in maize plants infested with bird-cherry-oat (Rhopalosiphum padi L.) aphids. However, there is no available data unveiling the impact of aphids feeding on oxidative damages of crucial macromolecules in maize tissues. Therefore, the purpose of the current study was to evaluate the scale of oxidative damages of genomic DNA, total RNA and mRNA, proteins, and lipids in seedling leaves of two maize genotypes (Złota Karłowa and Waza cvs—susceptible and relatively resistant to the aphids, respectively). The content of oxidized guanosine residues (8-hydroxy-2′-deoxyguanosine; 8-OHdG) in genomic DNA, 8-hydroxyguanosine (8-OHG) in RNA molecules, protein carbonyl groups, total thiols (T-SH), protein-bound thiols (PB-SH), non-protein thiols (NP-SH), malondialdehyde (MDA) and electrolyte leakage (EL) levels in maze plants were determined. In addition, the electrical penetration graphs (EPG) technique was used to monitor and the aphid stylet positioning and feeding modes in the hosts. Maize seedlings were infested with 0 (control), 30 or 60 R. padi adult apterae per plant. Substantial increases in the levels of RNA, protein and lipid oxidation markers in response to aphid herbivory, but no significant oxidative damages of genomic DNA, were found. Alterations in the studied parameters were dependent on maize genotype, insect abundance and infestation time.
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Pfaff, Annalise R., Justin Beltz, Emily King, and Nuran Ercal. "Medicinal Thiols: Current Status and New Perspectives." Mini-Reviews in Medicinal Chemistry 20, no. 6 (2020): 513–29. http://dx.doi.org/10.2174/1389557519666191119144100.
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The thiol (-SH) functional group is found in a number of drug compounds and confers a unique combination of useful properties. Thiol-containing drugs can reduce radicals and other toxic electrophiles, restore cellular thiol pools, and form stable complexes with heavy metals such as lead, arsenic, and copper. Thus, thiols can treat a variety of conditions by serving as radical scavengers, GSH prodrugs, or metal chelators. Many of the compounds discussed here have been in use for decades, yet continued exploration of their properties has yielded new understanding in recent years, which can be used to optimize their clinical application and provide insights into the development of new treatments. The purpose of this narrative review is to highlight the biochemistry of currently used thiol drugs within the context of developments reported in the last five years. More specifically, this review focuses on thiol drugs that represent the standard of care for their associated conditions, including N-acetylcysteine, 2,3-meso-dimercaptosuccinic acid, British anti-Lewisite, D-penicillamine, amifostine, and others. Reports of novel dosing regimens, delivery strategies, and clinical applications for these compounds were examined with an eye toward emerging approaches to address a wide range of medical conditions in the future.
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Iciek, Małgorzata, Grazyna Chwatko, Elzbieta Lorenc-Koci, Edward Bald, and Lidia Włodek. "Plasma levels of total, free and protein bound thiols as well as sulfane sulfur in different age groups of rats." Acta Biochimica Polonica 51, no. 3 (2004): 815–24. http://dx.doi.org/10.18388/abp.2004_3564.
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The redox status of plasma thiols can be a diagnostic indicator of different pathological states. The aim of this study was to identify the age dependent changes in the plasma levels of total, free and protein bound glutathione, cysteine and homocysteine. The determination was conducted in plasma of three groups of rats: 1) young (3-month-old), 2) middle aged (19-month-old), and 3) old (31-month-old). Total levels of glutathione, cysteine and homocysteine and their respective free and protein-bound fractions decreased with age. The only exception was a rise in free homocysteine concentration in the middle group, which indicates a different pattern of transformations of this thiol in plasma. The drop in the level of protein-bound thiols suggests that the antioxidant capacity of plasma diminishes with age, which, consequently, leads to impaired protection of -SH groups through irreversible oxidation. The plasma sulfane sulfur level also declines with age, which means that aging is accompanied by inhibition of anaerobic sulfur metabolism.
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Npustroev, Kirill N., Elena V. Eneyskaya, Stepan V. Protasenya, Anatoly M. Kachurin, and Andrew N. Savel'ev. "SH-Group in the active site of u-galactosidase from trjchoderma reese/." Protein & Peptide Letters 4, no. 3 (1997): 173–80. http://dx.doi.org/10.2174/092986650403221017100953.
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Abstract: Modifications of an SH-group in active site of u-galactosidase from T. reesei by PHMB and Hg2+ inactivate the enzyme while following treatment with thiols activity is recovered. Galactose and substrates delay such recovery. This effect was utilized to compare affinity of substrates and galactose to native and inactive forms of the enzyme. It was concluded that the SH-group is important for binding of substrates in the active site.
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Lee, Duk-Shin, and Ji-Eun Kim. "PDI-Mediated Reduction of Disulfide Bond on PSD95 Increases Spontaneous Seizure Activity by Regulating NR2A–PSD95 Interaction in Epileptic Rats Independent of S-Nitrosylation." International Journal of Molecular Sciences 21, no. 6 (2020): 2094. http://dx.doi.org/10.3390/ijms21062094.
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Postsynaptic density-95 (PSD95), a major scaffolding protein, is critical in coupling N-methyl-D-aspartate receptor (NMDAR) to cellular signaling networks in the central nervous system. A couple of cysteine residues in the N-terminus of PSD95 are potential sites for disulfide bonding, S-nitrosylation and/or palmitoylation. Protein disulfide isomerase (PDI) reduces disulfide bonds (S-S) to free thiol (-SH) on various proteins. However, the involvement of PDI in disulfide bond formation/S-nitrosylation of PSD95 and its role in epilepsy are still unknown. In the present study, acute seizure activity significantly increased the bindings of PDI to NR2A, but not to PSD95, while it decreased the NR2A–PSD95 binding. In addition, pilocarpine-induced seizures increased the amount of nitrosylated (SNO-) thiols, not total (free and SNO-) thiols, on PSD95. Unlike acute seizure, spontaneous seizing rats showed the increases in PDI–PSD95 binding, total- and SNO-thiol levels on PSD95, and NR2A–PSD95 interaction. PDI siRNA effectively reduced spontaneous seizure activity with decreases in total thiol level on PSD95 and NR2A–PSD95 association. These findings indicate that PDI-mediated reduction of disulfide-bond formations may facilitate the NR2A–PSD95 binding and contribute to spontaneous seizure generation in epileptic animals.
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Spraakman, Nora A., Annemieke M. Coester, Arno R. Bourgonje, et al. "Systemic and Renal Dynamics of Free Sulfhydryl Groups during Living Donor Kidney Transplantation." International Journal of Molecular Sciences 23, no. 17 (2022): 9789. http://dx.doi.org/10.3390/ijms23179789.
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During ischemia–reperfusion injury (IRI), reactive oxygen species are produced that can be scavenged by free sulfhydryl groups (R-SH, free thiols). In this study, we hypothesized that R-SH levels decrease as a consequence of renal IRI and that R-SH levels reflect post-transplant graft function. Systemic venous, arterial, renal venous, and urinary samples were collected in donors and recipients before, during, and after transplantation. R-SH was measured colorimetrically. Systemic arterial R-SH levels in recipients increased significantly up to 30 sec after reperfusion (p < 0.001). In contrast, renal venous R-SH levels significantly decreased at 5 and 10 min compared to 30 sec after reperfusion (both p < 0.001). This resulted in a significant decrease in delta R-SH (defined as the difference between renal venous and systemic arterial R-SH levels) till 30 sec after reperfusion (p < 0.001), indicating a net decrease in R-SH levels across the transplanted kidney. Overall, these results suggest trans-renal oxidative stress as a consequence of IRI during kidney transplantation, reflected by systemic and renal changes in R-SH levels in transplant recipients.
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Hecker, M., I. Siegle, H. Macarthur, W. C. Sessa, and J. R. Vane. "Role of intracellular thiols in release of EDRF from cultured endothelial cells." American Journal of Physiology-Heart and Circulatory Physiology 262, no. 3 (1992): H888—H896. http://dx.doi.org/10.1152/ajpheart.1992.262.3.h888.
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The availability of intracellular reduced thiols, such as L-cysteine or glutathione (GSH), may be critically important for the biosynthesis of endothelium-derived relaxing factor (EDRF). We have, therefore, investigated the effects of various sulfhydryl (SH) reagents, such as 1-chloro-2,4-dinitrobenzene (CDNB), diamide, 2,2'-dithiodipyridine (DTDP), or N-ethyl-maleimide (NEM), on the release of EDRF from cultured endothelial cells. None of the SH reagents tested affected the flow-induced EDRF release, but DTDP and NEM inhibited the release of EDRF stimulated by ADP, ionomycin, or poly-L-lysine. In contrast, NG-nitro-L-arginine methyl ester, an inhibitor of EDRF biosynthesis, blocked both the flow- and agonist-induced release of EDRF. Although NEM substantially potentiated the flow-induced release of prostacyclin (PGI2), probably due to a blockade of the reacylation of arachidonic acid, it inhibited the stimulated release of PGI2, whereas diamide did not significantly affect either release. Like CDNB or diamide, NEM, but not DTDP, caused a significant decrease in endothelial GSH. In contrast, both NEM and DTDP, but not CDNB or diamide, inhibited the ADP-induced mobilization of intracellular calcium, suggesting that they act on specific target proteins involved in endothelial cell calcium homeostasis rather than intracellular free SH groups. Moreover, the selective inhibition by these two SH reagents of the stimulated release of EDRF implies that a fundamental regulatory difference exists between agonist- and flow-induced EDRF biosynthesis.
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Rosenberg, Michal, Štefan Baláž, Ernest Šturdík, and Anton Kuchár. "Reactivity of 2-furylethylenes with nucleophilic groups and its biological significance." Collection of Czechoslovak Chemical Communications 52, no. 2 (1987): 425–30. http://dx.doi.org/10.1135/cccc19870425.
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The paper describes addition-nucleophilic reactions of 1-(5-R1-2-furyl)-2-R2-R3-ethylenes with SH (thioglycolic acid), NH2 (glycine) and OH (phenol) nucleophiles, and with hydroxyl ions in aqueous media. The determined rate constants, of second order (dm3 mol-1 s-1), show that in the physiological conditions the preferential reaction will be that with thiols. The amino acid composition of proteins modified with 1-(5-nitro-2-furyl)-2-nitro-2-methoxycarbonylethylene has revealed that the only group affected was the SH group of cysteine. This finding points out the significance of addition-nucleophilic SH-interactions of 2-furylethylenes with the protein macromolecules and accounts for the high cytotoxicity of these compounds.
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Hanhela, PJ, and DB Paul. "Organic Curing Agents for Polysulfide Sealants. II. Additions of Thiols to Nitrile Oxides: Scope, Relative Reactivities and Application to the Cure of Polysulfide Sealants." Australian Journal of Chemistry 42, no. 8 (1989): 1257. http://dx.doi.org/10.1071/ch9891257.
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Efficient addition between various nitrile oxides and both short (C2) and long chain (C16) alkyl thiols , aliphatic dithiols and aryl thiols occurred rapidly at ambient temperature with the formation of thiohydroximic acid derivatives. Competitive experiments with bis( nitrile oxides) showed that for terephthalonitrile oxide the second addition proceeded more readily than the first whereas with anthracene-9,l0-bis(carbonitrile oxide) elevated temperatures were needed to obtain the diadduct. Relative reactivities of a number of thiols with nitrile oxides were also determined spectroscopically . Reaction between prop-2-ene-1-thiol and p-nitrobenzonitrile oxide afforded products resulting from both cycloaddition and 1,3-addition with the latter predominating. The polysulfide prepolymer LP-2 was cured effectively at ambient temperatures by both terephthalonitrile oxide and 4,4'-sulfonylbisbenzonitrile dioxide at CNO to SH ratios of 1.5 and higher giving tack-free products within 0.5 h and 90% cure in under 4 h. For the less highly cross-linked LP-32-based sealants, curing was a little slower. Unreinforced sealants produced in this manner were firm elastomers with hardness of 35-40 (Rex A). The naphthalenebis (carbonitrile oxides) afforded softer products while anthracene-9,10- bis(carbonitrile oxide) was ineffective. One-part formulations involving in situ generation of nitrile oxide from hydroximoyl chlorides and barium hydroxide (formed by action of water vapour on barium oxide) were also produced.
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Glasco, Dalton Lee, and Jeffrey Gordon Bell. "Nonlinear Behavior during the Electrochemical Oxidation of Thiols." ECS Meeting Abstracts MA2022-01, no. 45 (2022): 1928. http://dx.doi.org/10.1149/ma2022-01451928mtgabs.
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The electrochemical behavior of sulfur-containing compounds is of great importance in fields ranging from diagnostics to energy-storage and materials chemistry. For example, thiols (R-SH) are important components of many electrochemical sensors and are routinely used in materials applications as they are known to form well-ordered and reproducible monolayers (self-assembled monolayers, SAMs) on various metal surfaces. Sulfur compounds are also interesting from the viewpoint of nonlinear dynamics owing to the presence of multiple oxidation states, which has been exploited to study complex dynamic behavior in both chemical and electrochemical systems. In this work we explore the oscillatory behavior of 2-(dimethylamino)ethanethiol (DMAET), a known hydrolysis product of V-type nerve agents, on platinum electrodes. Interestingly, the electrochemical oxidation of DMAET leads to two distinct regions of oscillatory behavior. Probing the system with electrochemical impedance spectroscopy (EIS), resulted in the classification of the DMAET system as an HN-NDR type oscillator. These results are compared to structurally similar thiol containing compounds towards the goal of elucidating general features which permit the evolution of dynamic behavior in thiol-based electrochemical systems.
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Khramtsov, Valery V., Igor A. Grigor’ev, David J. Lurie, Margaret A. Foster, Jay L. Zweier, and Periannan Kuppusamy. "Spin pH and SH probes: enhancing functionality of EPR-based techniques." Spectroscopy 18, no. 2 (2004): 213–25. http://dx.doi.org/10.1155/2004/870630.
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Along with significant progress in low-frequency electron spin resonance (ESR, also called electron paramagnetic resonance, EPR), other techniques such as Longitudinally-Detected ESR (LODESR), proton electron double-resonance imaging (PEDRI) and field-cycled dynamic nuclear polarization (FC-DNP) have been developed forin vivoapplications. However their potential is still far from maximally defined, in part, because of the need for new specific function-directed spin probes. An application of stable nitroxides of imidazoline and imidazolidine types provides unique possibility to measure local values of pH and thiol content in various biological systems, includingin vivostudies. These applications are based on the observation of specific chemical reactions of these nitroxides with protons or thiols, followed by significant changes in their EPR spectra. To increase sensitivity of pH probes for low-frequency EPR spectroscopy we evaluated two alternative approaches: (i) application of isotopically substituted labels, and (ii) acquisition of EPR spectra at high modulation amplitude. Spatial and spectral-spatial imaging (pH-mapping) using PEDRI and L-band EPR imagers were performed both on phantom samples andin vivo. The applications of the pH and SH probes in model systems, biological fluids, andin vivoin living animals are discussed.
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Bergsma, Anna T., Hui Ting Li, Jitske Eliveld, et al. "Local and Systemic Oxidative Stress Biomarkers for Male Infertility: The ORION Study." Antioxidants 11, no. 6 (2022): 1045. http://dx.doi.org/10.3390/antiox11061045.
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Infertility problems occur in around 10% of all couples worldwide, with male-factor infertility as the sole contributor in 20–30% of these cases. Oxidative stress (OS) is suggested to be associated with the pathophysiology of male infertility. In spermatozoa, OS can lead to damage to the cell membrane, resulting in disruption of DNA integrity and a decrease in motility. Established biomarkers for OS include free thiols and malondialdehyde (MDA), both representing different components of the reactive species interactome (RSI). This exploratory study aimed to investigate seminal plasma-free thiol and MDA levels in relation to semen parameters as defined by the World Health Organization (WHO) to determine if these markers are adequate to define local OS status. Furthermore, this study investigated if there is a relation between systemic and local OS status by comparing seminal concentrations of free thiol (R-SH, sulfhydryl groups, representing the extracellular redox status) and MDA (lipid peroxidation product) levels to those measured in serum. Free thiol and MDA measurements in both serum and semen plasma were performed in 50 males (18–55 y) of couples seeking fertility treatment. A significant positive correlation was found between seminal plasma-free thiol levels and sperm concentration and progressive motility (r = 0.383, p = 0.008 and r = 0.333, p = 0.022, respectively). In addition, a significant positive correlation was found between MDA levels in seminal plasma and sperm concentration (r = 0.314, p = 0.031). This study supports that seminal plasma-free thiols may be promising as local OS biomarkers. No associations were observed between local and systemic OS biomarker concentrations.
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Kesarwani, Pravin, Amir Al-Khami, Navtej Kaur, et al. "Expression of redox-regulating molecules rather than mitochondrial biogenesis correlate with susceptibility to apoptotic stimuli in human CD62L T cell subsets (P1034)." Journal of Immunology 190, no. 1_Supplement (2013): 65.18. http://dx.doi.org/10.4049/jimmunol.190.supp.65.18.
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Abstract Ex vivo-expanded CD8+ T cells used for adoptive immunotherapy generally acquire an effector memory-like phenotype (TEM cells) and exhibit impaired in vivo persistence and anti-tumor efficacy, compared to T cells with central memory-like phenotype (TCM cells). However, the intrinsic and metabolic factors that attribute to this differential outcome of T cell subsets are not well understood. Here we show that CD62Lhi TCM-like T cells exhibited increased expression of cell surface sulphydryl groups (-SH; thiols), compared to TEM phenotype like CD62Llo TEM-like T cells. This increase in thiols coincided with an up-regulation of the redox-regulating anti-oxidant proteins catalase, SOD1, NRF2 and inversely correlated to the generation of ROS, RNS, extent of T cell proliferation and glycolytic enzymes. Further, we observed that T cells pretreated with rapamycin, a drug that favors the generation of a CD62Lhi TCM-like phenotype of T cells and renders reduced susceptibility to apoptosis, also up-regulated thiol expression and level of anti-oxidative genes. Conversely, thiol donor L-NAC pretreatment reduced mTOR activation. However, both rapamycin and L-NAC treated T cells showed a decrease in oxygen consumption rate, key glycolytic enzymes and expression of PGC1α, a key regulator of mitochondrial biogenesis. These data suggest that modulation of anti-oxidant capacity, mitochondrial metabolism and glycolytic pathway of T cell subsets could increase persistence and improve immunotherapy.
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van der Slikke, Elisabeth C., Lisanne Boekhoud, Arno R. Bourgonje, et al. "Plasma Free Thiol Levels during Early Sepsis Predict Future Renal Function Decline." Antioxidants 11, no. 5 (2022): 800. http://dx.doi.org/10.3390/antiox11050800.
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Sepsis is a life-threatening syndrome characterized by acute organ dysfunction due to infection. In particular, acute kidney injury (AKI) is common among patients with sepsis and is associated with increased mortality and morbidity. Oxidative stress is an important contributor to the pathogenesis of sepsis-related AKI. Plasma free thiols (R-SH) reflect systemic oxidative stress since they are readily oxidized by reactive species and thereby serve as antioxidants. Here, we aimed to assess the concentrations of serum free thiols in sepsis and associate these with major adverse kidney events (MAKE). Adult non-trauma patients who presented at the emergency department (ED) with a suspected infection were included. Free thiol levels and ischemia-modified albumin (IMA), a marker of oxidative stress, were measured in plasma at baseline, at the ward, and at three months, and one year after hospitalization. Plasma free thiol levels were lower at the ED visit and at the ward as compared to three months and one year after hospital admission (p < 0.01). On the contrary, plasma levels of IMA were higher at the ED and at the ward compared to three months and one year after hospital admission (p < 0.01). Furthermore, univariate logistic regression analyses showed that plasma free thiol levels at the ED were inversely associated with long-term renal function decline and survival at 90 days (MAKE90) and 365 days (MAKE365) (OR 0.43 per standard deviation [SD] [0.22–0.82, 95% CI], p = 0.011 and OR 0.58 per SD [0.34–0.96, 95% CI], p = 0.035, respectively). A multivariate regression analysis revealed an independent association of plasma free thiols at the ED (OR 0.52 per SD [0.29–0.93, 95% CI], p = 0.028) with MAKE365, even after adjustments for age, eGFR at the ED, SOFA score, and cardiovascular disease. These data indicate the clear role of oxidative stress in the pathogenesis of sepsis-AKI, as reflected in the lower plasma free thiol levels and increased levels of IMA.
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Mori, Kunio, Hidetoshi Hirahara, and Yoshiyuki Oishi. "Direct Adhesion between Electroless Nickel-P Plated Metals and NBR Compounds during Curing." Rubber Chemistry and Technology 70, no. 2 (1997): 211–21. http://dx.doi.org/10.5254/1.3538426.
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Abstract In this study, an examination was made of the various causative factors for the direct adhesion between nickel-P alloy (nickel alloy) and acrylonitrile-butadiene rubber (NBR) compounds during curing. In a high sulfur curing system (SV), direct adhesion was found to depend on time of exposure to air and not to occur after more than 48 h of exposure. In the peroxide curing system (PV), there was no adhesion at all regardless of the exposure time. The addition of triazine thiols to NBR compounds resulted in adhesion between NBR compounds and nickel alloy for exposures exceeding 48 h. Typical curing systems such as SV, low sulfur curing (LSV), sulfurless curing (SLV), and PV gave good NBR-nickel adherends when the NBR compounds contained the monosodium salt of triazine trithiol (TTN). In these system, peel strength in the adherends increased with triazine thiols, to a maximum, and then decreased. This parameter was influenced by the chemical structures of triazine thiols, such as those containing thiol(-SH) and the sodium salt of thiol (-SNa) groups, and by the exposure of nickel alloy to air. Peel strength decreased with the formation of nickel oxides on the surface. When the nickel oxides were removed from the nickel alloy surface, peel strength was recovered. High peel-strength adhesion between NBR compounds with TTN and nickel alloy is due to the formation of interfacial bonds and reinforcement layers at the adhesive interface during curing. Adherends consisting of NBR compounds with TTN and nickel alloy generally showed high heat resistance, oil resistance, and water resistance. The values for these parameters differed accordingly to the curing system and were optimal in the following order: SV &lt; SV with TTN &lt; PV with TTN.
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van Dijk, Peter R., Amaal Eman Abdulle, Marian L. C. Bulthuis, et al. "The Systemic Redox Status Is Maintained in Non-Smoking Type 2 Diabetic Subjects Without Cardiovascular Disease: Association with Elevated Triglycerides and Large VLDL." Journal of Clinical Medicine 9, no. 1 (2019): 49. http://dx.doi.org/10.3390/jcm9010049.
Full textAbstract:
Decreased circulating levels of free thiols (R-SH, sulfhydryl groups) reflect enhanced oxidative stress, which plays an important role in the pathogenesis of cardiometabolic diseases. Since hyperglycemia causes oxidative stress, we questioned whether plasma free thiols are altered in patients with type 2 diabetes mellitus (T2DM) without cardiovascular disease or renal function impairment. We also determined their relationship with elevated triglycerides and very low density lipoproteins (VLDL), a central feature of diabetic dyslipidemia. Fasting plasma free thiols (colorimetric method), lipoproteins, VLDL (nuclear magnetic resonance spectrometry), free fatty acids (FFA), phospholipid transfer protein (PLTP) activity and adiponectin were measured in 79 adult non-smoking T2DM subjects (HbA1c 51 ± 8 mmol/mol, no use of insulin or lipid lowering drugs), and in 89 non-smoking subjects without T2DM. Plasma free thiols were univariately correlated with glucose (r = 0.196, p < 0.05), but were not decreased in T2DM subjects versus non-diabetic subjects (p = 0.31). Free thiols were higher in subjects with (663 ± 84 µmol/L) versus subjects without elevated triglycerides (619 ± 91 µmol/L; p = 0.002). Age- and sex-adjusted multivariable linear regression analysis demonstrated that plasma triglycerides were positively and independently associated with free thiols (β = 0.215, p = 0.004), FFA (β = 0.168, p = 0.029) and PLTP activity (β = 0.228, p = 0.002), inversely with adiponectin (β = −0.308, p < 0.001) but not with glucose (β = 0.052, p = 0.51). Notably, the positive association of free thiols with (elevated) triglycerides appeared to be particularly evident in men. Additionally, large VLDL were independently associated with free thiols (β = 0.188, p = 0.029). In conclusion, circulating free thiols are not decreased in this cohort of non-smoking and generally well-controlled T2DM subjects. Paradoxically, higher triglycerides and more large VLDL particles are likely associated with higher plasma levels of thiols, reflecting lower systemic oxidative stress.
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Zheng, Yan, Peng Hou, Yu Li, et al. "A Phenothiazine-HPQ Based Fluorescent Probe with a Large Stokes Shift for Sensing Biothiols in Living Systems." Molecules 26, no. 8 (2021): 2337. http://dx.doi.org/10.3390/molecules26082337.
Full textAbstract:
Due to the redox properties closely related to numerous physiological and pathological processes, biothiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), have received considerable attention in biological science. On account of the important physiological roles of these biothiols, it is of profound significance to develop sensitive and selective detection of biothiols to understand their biological profiles. In this work, we reported an efficient fluorescent probe, PHPQ-SH, for detecting biothiols in vitro and vivo, based on the phenothiazine-HPQ skeleton, with DNBS (2,4-dinitrobenzenesulfonate) as the response unit. Probe PHPQ-SH exhibited brilliant sensing performances toward thiols, including a large Stokes shift (138 nm), excellent sensitivity (for GSH, LOD = 18.3 nM), remarkable fluorescence enhancement (163-fold), low cytotoxicity, rapid response (8 min), and extraordinary selectivity. Finally, the probe PHPQ-SH illustrated herein was capable of responding and visualizing biothiols in MCF-7 cells and zebrafish.
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Tsikas, Dimitrios. "Extra-platelet low-molecular-mass thiols mediate the inhibitory action of S-nitrosoalbumin on human platelet aggregation via S-transnitrosylation of the platelet surface." Amino Acids 53, no. 4 (2021): 563–73. http://dx.doi.org/10.1007/s00726-021-02950-8.
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AbstractNitrosylation of sulfhydryl (SH) groups of cysteine (Cys) moieties is an important post-translational modification (PTM), often on a par with phosphorylation. S-Nitrosoalbumin (ALB-Cys34SNO; SNALB) in plasma and S-nitrosohemoglobin (Hb-Cysβ93SNO; HbSNO) in red blood cells are considered the most abundant high-molecular-mass pools of nitric oxide (NO) bioactivity in the human circulation. SNALB per se is not an NO donor. Yet, it acts as a vasodilator and an inhibitor of platelet aggregation. SNALB can be formed by nitrosation of the sole reduced Cys group of albumin (Cys34) by nitrosating species such as nitrous acid (HONO) and nitrous anhydride (N2O3), two unstable intermediates of NO autoxidation. SNALB can also be formed by the transfer (S-transnitrosylation) of the nitrosyl group (NO+) of a low-molecular-mass (LMM) S-nitrosothiol (RSNO) to ALB-Cys34SH. In the present study, the effects of LMM thiols on the inhibitory potential of ALB-Cys34SNO on human washed platelets were investigated. ALB-Cys34SNO was prepared by reacting n-butylnitrite with albumin after selective extraction from plasma of a healthy donor on HiTrapBlue Sepharose cartridges. ALB-Cys34SNO was used in platelet aggregation measurements after extended purification on HiTrapBlue Sepharose and enrichment by ultrafiltration (cutoff, 20 kDa). All tested LMM cysteinyl thiols (R-CysSH) including l-cysteine and L-homocysteine (at 10 µM) were found to mediate the collagen-induced (1 µg/mL) aggregation of human washed platelets by SNALB (range, 0–10 µM) by cGMP-dependent and cGMP-independent mechanisms. The LMM thiols themselves did not affect platelet aggregation. It is assumed that the underlying mechanism involves S-transnitrosylation of SH groups of the platelet surface by LMM RSNO formed through the reaction of SNALB with the thiols: ALB-Cys34SNO + R-CysSH ↔ ALB-Cys34SH + R-CysSNO. Such S-transnitrosylation reactions may be accompanied by release of NO finally resulting in cGMP-dependent and cGMP-independent mechanisms.
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Csako, G. "False-positive results for ketone with the drug mesna and other free-sulfhydryl compounds." Clinical Chemistry 33, no. 2 (1987): 289–92. http://dx.doi.org/10.1093/clinchem/33.2.289.
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Abstract All free-sulfhydryl compounds tested produced false-positive reactions in the Legal test for ketones. The color developed in the ketone pad of urine dipsticks [N-Multistix SG, Multistix 10 SG (Ames), and Chemstrip 9 (Boehringer-Mannheim)] was misinterpreted for ketone bodies, both by visual and automated reading. In contrast to the reaction with true ketones, a drop of glacial acetic acid added onto the ketone pad of dipsticks discharged the false-positive red color. A red-violet also developed instantly with free -SH compounds in the Acetest tablet assay (Ames), but quickly faded. In general, the presence of acidic groups such as -COOH and -SO3H in the structure appeared to increase the nitroprusside reactivity of free -SH compounds, whereas the presence of a -NH2 group appeared to decrease it. Currently, false-positive ketone reactions ascribable to a free -SH group are most likely to be seen for urine containing mesna. The false-positive test for ketones caused by free -SH compounds can be recognized and ruled out by proper procedures. On the other hand, this chromogenic reaction with free thiols might be used for monitoring urinary excretion of mesna.
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Le Gal, Marion, Estelle Renard, Christelle Simon-Colin, Benoit Larrat, and Valérie Langlois. "Amphiphilic and Perfluorinated Poly(3-Hydroxyalkanoate) Nanocapsules for 19F Magnetic Resonance Imaging." Bioengineering 8, no. 9 (2021): 121. http://dx.doi.org/10.3390/bioengineering8090121.
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Nanoparticles have recently emerged as valuable tools in biomedical imaging techniques. Here PEGylated and fluorinated nanocapsules based on poly(3-hydroxyalkanoate) containing a liquid core of perfluorooctyl bromide PFOB were formulated by an emulsion-evaporation process as potential 19F MRI imaging agents. Unsaturated poly(hydroxyalkanoate), PHAU, was produced by marine bacteria using coprah oil and undecenoic acid as substrates. PHA-g-(F; PEG) was prepared by two successive controlled thiol-ene reactions from PHAU with firstly three fluorinated thiols having from 3 up to 17 fluorine atoms and secondly with PEG-SH. The resulting PHA-g-(F; PEG)-based PFOB nanocapsules, with a diameter close to 250–300 nm, are shown to be visible in 19F MRI with an acquisition time of 15 min. The results showed that PFOB-nanocapsules based on PHA-g-(F; PEG) have the potential to be used as novel contrast agents for 19F MRI.
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Kesarwani, Pravin, Krishnamurthy Thyagarajan, Myroslawa Soloshchenko, Shilpak Chatterjee, Nilanjana Maulik, and Shikhar Mehrotra. "Increased expression of anti-oxidant molecule Thioredoxin-1 on T cells improves immunotherapeutic control of tumors (VAC7P.1039)." Journal of Immunology 194, no. 1_Supplement (2015): 143.9. http://dx.doi.org/10.4049/jimmunol.194.supp.143.9.
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Abstract Adoptive transfer of tumor epitope reactive T cells is a promising strategy to control tumor growth. However, chronically stimulated T cells expanded for adoptive cell transfer (ACT) are susceptible to cells death in an oxidative tumor microenvironment. Since oxidation of cell surface thiols (c-SH) also alters functionality of proteins, we hypothesized that increased level of thioredoxin, an anti-oxidant molecule that facilitates reduction of proteins by cysteine thiol-disulfide exchange, in T cells will result in sustained anti-tumor function. We thus crossed Trx1 transgenic mice with gp100 reactive TCR (Pmel) to generate Pmel/Trx mice. The Trx overexpressing transgenic T cells expressed higher thiols that inversely correlated with ROS, and susceptibility to TCR restimulation or H2O2 mediated cell death. These Trx1 expressing T cells showed CD62Lhi central memory-like (TCM) phenotype with reduced effector function (IFNglo2-NBDGlo), and were less effective in controlling tumor upon adoptive transfer. However, adoptive transfer of Pmel cells mixed with Pmel/Trx1 cells in 1:1 ratio markedly improved tumor control as compared to the mice that were transferred Pmel or Pmel/Trx T cells alone. It is likely that Pmel immediate effectors and Pmel/Trx cells with T-stem cell memory phenotype (i.e. CD62LhiCD44loCD122+Sca1hi), contributed to the improved tumor control. Thus, strategies to increase anti-oxidant capacity of anti-tumor T cells could have immunotherapeutic implications.
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Robertson, Nancy Weeks, and Stan R. Blecher. "Epidermal growth factor (EGF) affects sulphydryl and disulphide levels in cultured mouse skin : possible relationship between effects of EGF and of the tabby gene on thiols." Biochemistry and Cell Biology 65, no. 7 (1987): 658–67. http://dx.doi.org/10.1139/o87-087.
Full textAbstract:
Studies from our laboratory have previously shown that the syndrome produced in the mouse by the X-linked gene tabby (Ta) has many features in common with human X-linked hypohidrotic ectodermal dysplasia. We have also demonstrated that tabby has abnormally elevated epidermal sulphydryl (SH) : disulphide (SS) ratios, in common with an autosomal form of ectodermal dysplasia. The organs and tissues affected in many of the traits of these syndromes are targets of epidermal growth factor (EGF) and we have shown that the EGF-producing cells are deficient in tabby. In the present study we examined whether EGF affects SH and SS levels in normal mouse skin in tissue culture, and we report here that it does. EGF at a concentration of 25 ng/mL tissue culture medium lowers SH levels as compared with controls (0 ng/mL) in the epidermal layers examined (stratum malpighii of the tail and stratum malpighii and stratum corneum of flank skin). In general, other concentrations of EGF increase epidermal SH levels, although very high doses also reduce them. EGF at 25 ng/mL also lowers total SH + SS concentrations in the epidermal layers. Fetuses hemizygous for the Ta gene appear to have higher total SH + SS epidermal concentrations than their wild-type control littermates. These data, taken together with some of our previous findings, suggest the possibility that a relationship may exist between Ta, EGF, and thiol concentrations. Further study is required to elucidate this relationship.
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Khanra, Tapan Kumar, Basudam Adhikari, and Sukumar Maiti. "Multifunctional Activities of Benzazole Derivatives in Rubber Vulcanization." Rubber Chemistry and Technology 66, no. 1 (1993): 30–37. http://dx.doi.org/10.5254/1.3538297.
Full textAbstract:
Abstract Benzazole thiol (e.g. 2-Mercaptobenzothiazole and 2-Mercaptobenzimidazole) and sulfenamide (e.g. 2-Morpholino thiobenzothiazole) are used as rubber chemicals. The nature and the extent of their performances in rubber depend on the nature of the key heteroatom present in the azole ring. It has been found that the presence of X (S or N) as the key heteroatom in the grouping —X—‖—SH of the azole ring is responsible for either accelerator or antioxidant action. Although some scattered informations on accelerator and antioxidant functions are available for some of the benzazole derivatives, their comparative ratings in these functions are not found in the literature. In the present communication, synthesis and characterization of some benzazole sulfenamides are reported. Together with this, a comparative evaluation of accelerator-cum-anti-oxidant properties of both the benzazole thiols and sulfenamides is described. Such dual function rubber chemicals are unusual and novel and should fetch a premium price as rubber additives.
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Neves, Ricardo Pires das, Mónica Chagoyen, Antonio Martinez-Lorente, et al. "Each Cellular Compartment Has a Characteristic Protein Reactive Cysteine Ratio Determining Its Sensitivity to Oxidation." Antioxidants 12, no. 6 (2023): 1274. http://dx.doi.org/10.3390/antiox12061274.
Full textAbstract:
Signaling and detoxification of Reactive Oxygen Species (ROS) are important patho-physiologcal processes. Despite this, we lack comprehensive information on individual cells and cellular structures and functions affected by ROS, which is essential to build quantitative models of the effects of ROS. The thiol groups from cysteines (Cys) in proteins play a major role in redox defense, signaling, and protein function. In this study, we show that the proteins in each subcellular compartment contain a characteristic Cys amount. Using a fluorescent assay for -SH in thiolate form and amino groups in proteins, we show that the thiolate content correlates with ROS sensitivity and signaling properties of each compartment. The highest absolute thiolate concentration was found in the nucleolus, followed by the nucleoplasm and cytoplasm whereas protein thiolate groups per protein showed an inverse pattern. In the nucleoplasm, protein reactive thiols concentrated in SC35 speckles, SMN, and the IBODY that accumulated oxidized RNA. Our findings have important functional consequences, and explain differential sensitivity to ROS.
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Lepedda, Antonio Junior, and Marilena Formato. "Oxidative Modifications in Advanced Atherosclerotic Plaques: A Focus on In Situ Protein Sulfhydryl Group Oxidation." Oxidative Medicine and Cellular Longevity 2020 (January 9, 2020): 1–7. http://dx.doi.org/10.1155/2020/6169825.
Full textAbstract:
Although oxidative stress has been long associated with the genesis and progression of the atherosclerotic plaque, scanty data on its in situ effects on protein sulfhydryl group modifications are available. Within the arterial wall, protein sulfhydryls and low-molecular-weight (LMW) thiols are involved in the cell regulation of both Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) levels and are a target for several posttranslational oxidative modifications that take place inside the atherosclerotic plaque, probably contributing to both atherogenesis and atherosclerotic plaque progression towards complicated lesions. Advanced carotid plaques are characterized by very high intraplaque GSH levels, due to cell lysis during apoptotic and/or necrotic events, probably responsible for the altered equilibrium among protein sulfhydryls and LMW thiols. Some lines of evidence show that the prooxidant environment present in atherosclerotic tissue could modify filtered proteins also by protein-SH group oxidation, and demonstrate that particularly albumin, once filtered, represents a harmful source of homocysteine and cysteinylglycine inside the plaque. The oxidative modification of protein sulfhydryls, with particular emphasis to protein thiolation by LMW thiols and its association with atherosclerosis, is the main topic of this review.
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Demain, Arnold L., and Spyridon N. Agathos. "Studies on in vivo inactivation of gramicidin S synthetase and its retardation." Canadian Journal of Microbiology 32, no. 3 (1986): 208–14. http://dx.doi.org/10.1139/m86-042.
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The oxygen-dependent in vivo inactivation of gramicidin S synthetase was investigated in Bacillus brevis ATCC 9999. Inhibitors of energy metabolism and of protein synthesis added to aerated cell suspensions did not provide any protection against inactivation, thus indicating that the process does not depend on energy-yielding metabolism nor on de novo protein synthesis. Organic thiols added to anaerobic long-term incubations retarded synthetase inactivation for several hours, whereas in short-term incubations of previously air-exposed cells they resulted in partial restoration of activity. The in vivo inactivation of the enzyme was found to be accompanied by a parallel drop in intracellular thiols. These results implicate enzyme SH oxidation as a mechanism of in vivo inactivation. Retardation of inactivation was achieved upon addition of utilizable carbon sources (glycerol, fructose, inositol) to aerated cell suspensions in buffer, the degree of stabilization being proportional to the ease of uptake and to the concentration of C source. This effect involves actual consumption of the exogenous C source and is accompanied by lower dissolved oxygen levels in the cell suspension. Pulsed additions of C source could retard inactivation but could not restore partly or fully lost activity. The C-source effect was blocked by the uncoupler dinitrophenol, while dissolved oxygen levels in the suspension remained low. C-source-supplemented cell suspensions incubated under air had a decreased intracellular redox state, as revealed by intracellular SH concentration.
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Lepedda, Antonio Junior, Angelo Zinellu, Gabriele Nieddu, et al. "Protein Sulfhydryl Group Oxidation and Mixed-Disulfide Modifications in Stable and Unstable Human Carotid Plaques." Oxidative Medicine and Cellular Longevity 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/403973.
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Objectives. Oxidative stress has been implicated in the outcome of atherosclerotic plaques. However, at present, no data are available neither on the degree of plaque protein sulfhydryl groups oxidation nor on its relationship with plaque vulnerability. We investigated the entity of protein-SH oxidative modifications, focusing on low molecular weight thiols adduction, in human carotid plaque extracts in relation to plaque stability/instability.Methods. Plaque stability/instability was histologically assessed. The extent of protein-SH oxidative modifications was established by a differential proteomic approach on fluorescein-5-maleimide-labeled plaque extracts and corresponding plasma samples from 48 endarterectomized patients. The analysis on protein thiolation was performed by capillary zone electrophoresis.Results. We observed a higher protein-SH oxidation of both plasma-derived and topically expressed proteins in unstable plaques, partly due to higher levels of S-thiolation. Conversely, in plasma, none of the investigated parameters discriminated among patients with stable and unstable plaques.Conclusions. Our results suggest the presence of a more pronounced oxidative environment in unstable plaques. Identifying specific oxidative modifications and understanding their effects on protein function could provide further insight into the relevance of oxidative stress in atherosclerosis.
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Eligini, Sonia, Marco Munno, Gloria Modafferi, Daphne Atlas, and Cristina Banfi. "N-Acetylcysteine, N-Acetylcysteine Amide, and Thioredoxin Mimetic Peptides Regenerate Mercaptoalbumin and Exhibit Antioxidant Activity." Antioxidants 13, no. 3 (2024): 351. http://dx.doi.org/10.3390/antiox13030351.
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Albumin (HSA) is the most abundant circulating protein and plays a pivotal role in maintaining the redox state of the plasma. Three HSA proteoforms have been identified based on the redox state of cysteine 34. These proteoforms comprise of the reduced state (HSA-SH) referred to as mercaptoalbumin, non-mercaptoalbumin-1, containing a disulfide with small thiols such as cysteine (HSA-Cys), and non-mercaptoalbumin-2, representing the higher oxidized proteoform. Several clinical studies have shown a relationship between an individual’s serum HSA redox status and the severity of diseases such as heart failure, diabetes mellitus, and liver disease. Furthermore, when HSA undergoes oxidation, it can worsen certain health conditions and contribute to their advancement. This study aimed to evaluate the ability of the redox compounds AD4/NACA and the thioredoxin mimetic (TXM) peptides TXM-CB3, TXM-CB13, and TXM-CB30 to regenerate HSA-SH and to enhance its redox activity. The HSA proteoforms were quantified by LC-MS, and the antioxidant activity was determined using dichlorofluorescin. Each of the compounds exhibited a significant increase in HSA-SH and a reduction in HSA-Cys levels. The increase in HSA-SH was associated with a recovery of its antioxidant activity. In this work, we unveil a novel mechanistic facet of the antioxidant activity of AD4/NACA and TXM peptides. These results suggest an additional therapeutic approach for addressing oxidative stress-related conditions.
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Veksler, Kirill V., Evgenia N. Volkova, and Alexander G. Gontсharenko. "HYDROPHOBIC AROMATIC THIO (DITHIO)COMPOUNDS AS CHROMOGENIC ANALYTICAL REAGENTS FOR PHOTOMETRIC DETERMINATION OF THIOLS BY MERCAPTO GROUP II. A UNIFIED MOLECULAR MODEL OF THE ANALYTICAL REAGENT." Bulletin of the Saint Petersburg State Institute of Technology (Technical University) 55 (2020): 49–57. http://dx.doi.org/10.36807/1998-9849-2020-55-81-49-57.
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The concept of a unified molecular model is proposed for the directed synthesis of chromogenic analytical reagents for the mercapto group in ("thiol-thiol") substitution reactions (SH reagents). The unified molecular model of the SH reagent includes an aromatic chromophore-containing thio fragment covalently bound by an ordinary bond on a sulfide sulfur atom to an electrophilic, relatively soft one [in terms of the principle of hard and soft acids and bases (the HSAB principle)] reaction center. The characteristics of the analytical effect of the SH reagent are determined by the structure of the thio fragment. The required change in the reactivity and selectivity of the SH reagent are achieved mainly by varying the softness (stiffness) of the reaction center. Spectral characteristics of analytical effects, reactivity and selectivity of SH reagents (obtained earlier and synthesized for the first time in this work) – hydrophobic aromatic thio (dithio) compounds: thiocyanates, symmetric disulfides, and thiomercuric compounds – were studied in an aprotic dipolar DMF medium. In support of the concept of the unified molecular model for compounds containing identical thiofragments it was established: - spectral characteristics of the analytical effect of all three types of compounds (thiocyanates, disulfides and thiomercuric compounds) are the same in the DMF medium. - in accordance with the principle of HSAB, the reactivity increases in the sequence thiocyanate < disulfide <<thiomercuric compound, which corresponds to an increase in the softness of the reaction center in the series: -С << - S-<< -Hg-. The universality of the concept of the unified molecular model follows from consideration of the spectral and kinetic characteristics not only of Ellman reagent, but as well of thio(dithio)azo compounds, thiocyanate and thiomercuric compound containing the same 3-carboxy, 4-nitrophenylthio fragment.
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Steiner, M. "Dynamics of Platelet Tubulin in Response to Changes in Free Sulfhydryl Groups." Thrombosis and Haemostasis 53, no. 02 (1985): 176–79. http://dx.doi.org/10.1055/s-0038-1661267.
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SummaryPools of polymerized and total tubulin were measured in human platelets as a function of free sulfhydryl groups both in acid-soluble and acid-precipitable cell fractions. Changes in free thiols were produced either by storage of platelets at room temperature or by addition of the potent oxidizing agent diazene dicarboxylic acid (diamide) and were correlated with shifts in the dynamic equilibrium between assembled and disassembled microtubules and platelet aggregation. Diamide at concentrations of 0.5 to 5 mM depleted acid soluble SH groups and reduced protein thiols while causing a progressive decrease in polymerized tubulin. Similar changes, although not as severe, were initiated by storage of platelets at room temperature. Platelet aggregation especially that induced by collagen showed a positive correlation with the pool of polymerized tubulin. Our results indicate that the state of oxidation of sulfhydryl groups especially in the acid- precipitable fraction plays an important role in determining the position of equilibrium between polymerized and depolymerized tubulin.
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EVENSON, DONALD P., LORNA K. JOST, MICHELE CORZETT, and ROD BALHORN. "Characteristics of Human Sperm Chromatin Structure Following an Episode of Influenza and High Fever: A Case Study." Journal of Andrology 21, no. 5 (2000): 739–46. http://dx.doi.org/10.1002/j.1939-4640.2000.tb02142.x.
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ABSTRACT: Semen samples from a fertile patient presenting with influenza and a 1‐day fever of 39.9°C were obtained and analyzed at 18–66 days postfever (dpf) for sperm nuclear proteins, DNA stainability, free thiols (—SH), and susceptibility to DNA denaturation in situ. At 18 dpf, 36% of sperm demonstrated denatured DNA as measured by the sperm chromatin structure assay (SCSA), and decreased to 23% by 39 dpf. Samples at 33 and 39 dpf contained 49% and 30%, respectively, of cells with increased DNA stainability (HIGRN). A unique sperm nuclear protein band migrating between histones and protamines on acid‐urea gels appeared at 33 and 39 dpf and nearly disappeared by 52 dpf. Amino acid sequencing of the first 8 N‐terminal residues identified this protein as the precursor to protamine 2. The protamine P1 and P2 ratio remained normal, whereas the histone to protamine ratio increased slightly at 33 to 39 dpf. Flow cytometric measurements of nuclear —SH groups revealed the greatest reduction in free nuclear thiols at 33 dpf, and returned to normal by 45 dpf. The time of appearance of the unprocessed protamine 2 precursor and the relative increase in histone suggest a fever‐related disruption of the synthesis of mRNA that codes for a P2 processing enzyme or enzymes. Increased DNA staining is likely due to the increased histone/protamine ratio. This case study demonstrates that fever/influenza can have latent effects on sperm chromatin structure and may result in transient release of abnormal sperm.
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Urbainsky, Claudia, Rolf Nölker, Marcel Imber, et al. "Nucleoredoxin-Dependent Targets and Processes in Neuronal Cells." Oxidative Medicine and Cellular Longevity 2018 (November 21, 2018): 1–11. http://dx.doi.org/10.1155/2018/4829872.
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Nucleoredoxin (Nrx) is an oxidoreductase of the thioredoxin family of proteins. It was shown to act as a signal transducer in some pathways; however, so far, no comprehensive analysis of its regulated substrates and functions was available. Here, we used a combination of two different strategies to fill this gap. First, we analyzed the thiol-redox state of the proteome of SH-SY5Y neuroblastoma cells depleted of Nrx compared to control cells using a differential thiol-labeling technique and quantitative mass spectrometry. 171 proteins were identified with an altered redox state; 161 of these were more reduced in the absence of Nrx. This suggests functions of Nrx in the oxidation of protein thiols. Second, we utilized the active site mutant Cys208Ser of Nrx, which stabilizes a mixed disulfide intermediate with its substrates and therefore trapped interacting proteins from the mouse brain (identifying 1710 proteins) and neuronal cell culture extracts (identifying 609 proteins). Profiling of the affected biological processes and molecular functions in cells of neuronal origin suggests numerous functions of Nrx in the redox regulation of metabolic pathways, cellular morphology, and signal transduction. These results characterize Nrx as a cellular oxidase that itself may be oxidized by the formation of disulfide relays with peroxiredoxins.
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Cain, Kelvin, Salmaan H. Inayat-Hussain, Ludmilla Kokileva, and Gerald M. Cohen. "DNA cleavage in rat liver nuclei activated by Mg2+ or Ca2+ + Mg2+ is inhibited by a variety of structurally unrelated inhibitors." Biochemistry and Cell Biology 72, no. 11-12 (1994): 631–38. http://dx.doi.org/10.1139/o94-083.
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Internucleosomal DNA fragmentation is often regarded as the biochemical hallmark of apoptosis and can be reproduced in vitro in rat liver nuclei. In this study we demonstrate that DNA is initially cleaved into ≥700, 200–250, and 30–50 kilobase pair (kbp) fragments via a Mg2+-dependent, multistep process which can be potentiated by Ca2+. The subsequent internucleosomal cleavage requires both Ca2+ and Mg2+. Furthermore, we show that the heavy metals Cd2+ and Hg2+, dichloroisocoumarin (a general serine protease inhibitor), and N-ethyl maleimide (NEM, a specific thiol reagent) are potent inhibitors of both the Mg2+- and Ca2+/Mg2+-stimulated DNA fragmentation. In contrast, two other serine protease inhibitors, N-α-tosyl-L-lysine chloromethylketone and N-tosyl-L-phenylalanine chloromethylketone are weak and ineffective, respectively, as inhibitors of DNA cleavage. Increasing inhibition of DNA cleavage is accompanied by a shift in the size of the cleaved DNA fragments, which increases from mono- + oligo-nucleosomes → 30–50 kbp → 200–300 kbp → ≥ 700 kbp → intact DNA. Dithiothreitol, a dithiol, blocks NEM and dichloroisocoumarin inhibition, and since Cd2+ and Hg2+ are also potent —SH blocking agents it is proposed that a critical thiol is involved in the cleavage of DNA into both large kbp fragments and oligonucleosomal-sized fragments.Key words: DNA cleavage, protease inhibitors, thiols.
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CECAN, Andra-Diana, Alina Elena PÂRVU, Marcel PÂRVU, et al. "Mahonia Aquifolium Flowers Extract Effects in Acute Experimental Inflammation." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Food Science and Technology 75, no. 2 (2018): 189. http://dx.doi.org/10.15835/buasvmcn-fst:2018.0019.
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Natural products were proved to have inhibitory effect on the nitro-oxidative stress. The aim of the study was to evaluate the effect of Mahonia aquifolium (MA) flowers extract upon nitro-oxidative stress in acute experimental inflammation. The extract was prepared by repercolation method. Acute experimental inflammation was induced with turpentine oil (0,6ml/kg b.w. i.m.). MA extract was given for 7 days. Were used 6 groups (n=5) of male Wistar rats: Groups 1-3 were with acute inflammation and treated with MA dilutions (100%, 50%, 25%); Group 4 was acute inflammation control; Group 5 was negative control; Group 6 was acute inflammation treated with diclofenac (10mg/kg b.w. p.o). In day 8 nitro-oxidative stress was evaluated by measuring serum nitrites and nitrates (NOx), Total oxidative stress (TOS), Total antioxidant capacity (TAC), Oxidative stress index (OSI), Malondialdehyde (MDA) and Thiols (SH). MA reduced OSI and TOS, increased SH, and had no important effect on TAC, NO and MDA. Compared to MA, Diclofenac was a stronger inhibitor of TOS and OSI, and had a smaller effect on SH. Mahonia aquifolium flowers extract had inhibitory effect on the oxidative stress, without influencing NO and lypoperoxides production, the effect being smaller than that of Diclofenac.
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Shoukry, Mohamed M., Bruce V. Cheesman, and Dallas L. Rabenstein. "Polarimetric and nuclear magnetic resonance studies of the complexation of mercury by thiols." Canadian Journal of Chemistry 66, no. 12 (1988): 3184–89. http://dx.doi.org/10.1139/v88-492.
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The complexation of Hg(II) by glutathione has been studied by polarimetry under conditions of excess ligand with the objective of characterizing formation of the 3:1 complex, Hg(glutathione)3. The optical rotatory power of solutions containing glutathione only and of solutions containing glutathione and Hg(II) at ratios of 2:1, 2.5:1, 3:1, and 4:1 was measured as a function of pH. Acid dissociation constants for the ammonium and thiol groups of glutathione and for the two ammonium groups of Hg(glutathione)2 and the formation constant of the 3:1 complex (Hg(glutathione)2 + glutathione [Formula: see text] Hg(glutathione)3) were determined from the pH dependence of the optical rotatory power. The value obtained for the formation constant, Kf = 1.5 × 103, indicates that binding of the third ligand to form Hg(glutathione)3 is much weaker than binding of the first two glutathione ligands. However, calculations indicate that binding is sufficiently strong that a significant fraction of Hg(II) is present as Hg(glutathione)3 under physiological conditions. Equilibrium constants were also determined by polarimetry and by 13C nuclear magnetic resonance for the displacement of one thiolate ligand by another (RSHgSR + R′SH [Formula: see text] RSHgSR′ + RSH; RSHgSR′ + R′SH [Formula: see text] R′SHgSR′ + RSH). The results indicate that, at pH 5.5 and at physiological pH, the relative stability increases in the order Hg(glutathione)2 < Hg(penicillamine)2 < Hg(mercaptoethylamine) 2. However, when competitive protonation of free ligand is accounted for, it is shown that the intrinsic stability of the complexes increases in the order Hg(penicillamine)2 < Hg(mercaptoethylamine)2 < Hg(glutathione)2, which parallels the order of the Brønsted basicity of the thiolate ligands.
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Minkwitz, Rolf, Ulrike Lohmann, and Hans Preut. "Primäre und sekundäre Ethyl-und i-Propylsulfoniumsalze sowie Kristallstruktur von i-C3H7SH2+SbF6- [1]." Zeitschrift für Naturforschung B 51, no. 2 (1996): 277–85. http://dx.doi.org/10.1515/znb-1996-0218.
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Abstract The synthesis of salts of the type RnSH3-n+MF6- (R = C2H5, i-C3H7; n = 1, 2; M = As, Sb) by protonation of the corresponding thiols and sulfides in the superacid systems HF/MF5 is reported. The salts have been characterized by vibrational and NMR spectroscopic methods. Isopropylsulfonium hexafluoroantimonate is the first known example of a sulfonium salt, for which a SH bond distance has been determined by a crystal structure analysis, i-C3H7SH2+SbF6- crystallizes in the monoclinic space group P21/m with a = 568.0(4), b = 801.1(6), c = 1019.7(8) pm, β = 82.63(6) °, with two formula units per unit cell.
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Lieberzeit, Peter A., Abdul Rehman, Bita Najafi, and Franz L. Dickert. "Generating Bio-Analogous Recognition of Artificial Materials – Sensors and Electronic Noses for Odours." Advances in Science and Technology 58 (September 2008): 103–7. http://dx.doi.org/10.4028/www.scientific.net/ast.58.103.
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Chemical sensing is a key application of bio-inspired smart materials. Artificial nanostructured layers mimicking biorecognition are synthetically accessible e.g. by imprinting techniques or affinity material nanoparticles. Hence, for detecting extremely malodorous organic thiols (butane/octance thiol), we designed molybdenum disulphide nanoparticles. In contrast to soft metals (e.g. gold) they interact with the SH-group fully reversibly leading to one of the first real QCM sensors for these compounds. Rationally varying the surface of the recognition material allows for optimizing the interaction properties. Electrolyzed gold e.g. shows sensor effects being about an order of magnitude higher than screen printed electrodes. Furthermore, molecular imprinting leads to highly selective cavities in polymers (polyurethanes, -styrenes, -acrylates) for detecting odorous compounds, e.g. aliphatic alcohols, ethyl acetate and limonene. With these materials, we designed an electronic nose for monitoring plant degradation processes based on a six-electrode QCM (quartz crystal microbalance) array. With a variety of degrading materials (grass, fruit, conifers), it determines the above analytes down to some ppm directly on-line. The concentration data can be extracted from the E-nose frequency shifts by Neural Networks and validated by GC-MS.