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1.
Xenobiotica ; 51(1): 31-39, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32744915

RESUMO

Targeted covalent inhibitors designed to bind covalently to a specific molecular target have recently been a focus of drug development. Among these inhibitors, thiol compounds bind covalently to endogenous thiols in the body through a process involving disulfide bonds. We investigated the predictability of changes in the exposure to captopril, tiopronin, the active form of dalcetrapib and the active metabolite of prasugrel, R-138727, all of which have a sulfhydryl group, in moderate and severe chronic kidney disease (CKD) patients using a constructed PBPK model. The changes in the exposure to captopril, tiopronin and the active form of dalcetrapib under CKD conditions were well predicted. However, the change in exposure to R-138727, which is a secondary metabolite of prasugrel, was overpredicted. Although these thiol compounds covalently bind to endogenous thiols, our study concluded that changes in exposure to these compounds under CKD conditions can probably be predicted, except for compounds with a complicated mechanism whereby the thiol metabolite is generated.


Assuntos
Insuficiência Renal Crônica/metabolismo , Compostos de Sulfidrila/metabolismo , Humanos , Pacientes , Farmacocinética
2.
Niger J Clin Pract ; 23(10): 1401-1406, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33047697

RESUMO

Aims: This study aimed to compare the serum thiol-disulfide homeostasis, total antioxidant status (TAS), and total oxidant status (TOS) in patients with pseudoexfoliation glaucoma (PEG) patients, primary open-angle glaucoma (POAG) patients, and healthy individuals (control). Methods: Ninety subjects were included in this study. Three groups were separated as PEG, POAG, and control. All groups were chosen to be similar in terms of age and gender. Blood samples were obtained following an overnight fasting state and were collected on the ice at 4°C. The serum samples were separated from the cells by centrifugation at 3000 rpm for 15 min and were stored at -80°C. Serum samples analyzed for TAS and TOS, native thiol, total thiol, disulfide, and native thiol/disulfide ratio. Results: TAS and TOS levels of PEG patients were 1.2892 ± 0.0905 mmol/L; 5.0191 ± 2.7722 µmol/L, respectively. TAS and TOS levels of POAG patients were 1.2741 ± 0.1252 mmol/L; 4.1674 ± 1.7723 µmol/L, respectively. TAS and TOS levels of the control group were 2.3414 ± 0.1409 mmol/L; 4.0931 ± 0.1107 µmol/L, respectively. The TAS level was significantly lower in PEG and POAG groups compared to control. TOS level showed no significant differ ¬ ence between PEG, POAG, and control groups (P > 0.05). The mean serum total thiol and native thiol levels were significantly lower in patients with PEG compared to POAG and control group; there was no significant difference between the POAG and control group (P > 0.05). The mean serum disulfide level was significantly lower in patients with PEG compared to POAG (P = 0.018). Conclusion: Low levels of TAS were observed in patients with glaucoma, which was likely a response to the increased oxidative stress observed in these patients. While total thiol and native thiol levels were higher in the PEG group, the disulfide level was higher in the POAG group. TAS and TOS levels showed no significant difference between POAG and PEG groups.


Assuntos
Antioxidantes/metabolismo , Dissulfetos/sangue , Síndrome de Exfoliação/sangue , Glaucoma de Ângulo Aberto/sangue , Homeostase/fisiologia , Compostos de Sulfidrila/sangue , Adulto , Antioxidantes/análise , Estudos de Casos e Controles , Dissulfetos/metabolismo , Síndrome de Exfoliação/metabolismo , Feminino , Glaucoma de Ângulo Aberto/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Óxido Nítrico/sangue , Oxidantes/sangue , Estresse Oxidativo/fisiologia , Compostos de Sulfidrila/metabolismo
3.
Proc Natl Acad Sci U S A ; 117(43): 26804-26811, 2020 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-33055209

RESUMO

The p53 tumor suppressor protein is a transcription factor and master stress response mediator, and it is subject to reduction-oxidation (redox)-dependent regulation. The P47S variant of TP53, which exists primarily in African-descent populations, associates with an elevated abundance of low molecular weight (LMW) thiols, including glutathione (GSH) and coenzyme A (CoA). Here we show that S47 and P47 cells exhibit distinct metabolic profiles, controlled by their different redox states and expression of Activating Transcription Factor-4 (ATF4). We find that S47 cells exhibit decreased catabolic glycolysis but increased use of the pentose phosphate pathway (PPP), and an enhanced abundance of the antioxidant, NADPH. We identify ATF4 as differentially expressed in P47 and S47 cells and show that ATF4 can reverse the redox status and rescue metabolism of S47 cells, as well as increase sensitivity to ferroptosis. This adaptive metabolic switch is rapid, reversible, and accompanied by thiol-mediated changes in the structures and activities of key glycolytic signaling pathway proteins, including GAPDH and G6PD. The results presented here unveil the important functional interplay among pathways regulating thiol-redox status, metabolic adaptation, and cellular responses to oxidative stress.


Assuntos
Fator 4 Ativador da Transcrição/metabolismo , Ferroptose , Genes p53 , Oxirredução , Compostos de Sulfidrila/metabolismo , Animais , Linhagem Celular , Coenzima A/metabolismo , Glutationa/metabolismo , Glicólise , Homeostase , Humanos , Masculino , Camundongos , Processamento de Proteína Pós-Traducional
4.
Yakugaku Zasshi ; 140(9): 1119-1128, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32879244

RESUMO

Humans are exposed to various xenobiotic electrophiles on a daily basis. Electrophiles form covalent adducts with nucleophilic residues of proteins. Redox signaling, which consists of effector molecules (e.g., kinases and transcription factors) and redox sensor proteins with low pKa cysteine residues, is involved in cell survival, cell proliferation, quality control of cellular proteins and oxidative stress response. Herein, we showed that at a low dose, xenobiotic electrophiles selectively modified redox sensor proteins through covalent modification of their reactive thiols, resulting in activation of a variety of redox signaling pathways. However, increasing the dose of xenobiotic electrophiles caused non-selective and extensive modification of cellular proteins involved in toxicity. Of interest, reactive sulfur species (RSS), such as hydrogen sulfide (H2S), cysteine persulfide (CysSSH), glutathione persulfide (GSSH) and even synthetic polysulfide (e.g., Na2S4), readily captured xenobiotic electrophiles, forming their sulfur adducts, which was associated with inactivation of the electrophiles. Our findings suggest that an adaptive response through redox signaling activation and RSS-mediated electrophile capturing is involved in the regulation of electrophilic stress.


Assuntos
Cisteína/análogos & derivados , Dissulfetos/metabolismo , Glutationa/análogos & derivados , Sulfeto de Hidrogênio/metabolismo , Oxirredução , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Animais , Cisteína/metabolismo , Glutationa/metabolismo , Humanos , Compostos de Sulfidrila/metabolismo , Xenobióticos/metabolismo
5.
Ecotoxicol Environ Saf ; 206: 111208, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32871521

RESUMO

Water management is an economic and effective strategy to reduce arsenic (As) accumulation in rice grains, but little is known about the effect of water management on the migration and transformation of As in the soil-rice system. In this study, the effect of the continually (CF) and intermittent flooding (IF) treatments on the dynamic change of As in the rhizosphere soil-pore water-iron plaque-rice system was systematically investigated using pot experiments. The expressions of genes involved in As uptake and translocation in rice plants under different water management treatments were further examined. Results showed that the total As concentration in brown rice was increased by 50.8% in the CF treatment compared to the IF treatment, and dimethylarsinic acid (DMA) made greater contribution (from 15.5% to 29.2%) to total As increase in brown rice under the CF treatment. The CF treatment increased As bioavailability in the rhizosphere soil and soil pore water, which enhanced As uptake and transport to the xylem in rice plants by inducing the expressions of silicon transporter genes (OsLsi1 and OsLsi2) compared to the IF treatment. Moreover, the CF treatment increased As translocation from roots to shoots by reducing soil available sulfur and phytochelatins (PCs) biosynthesis and vacuolar sequestration in rice roots compared with the IF treatment. The study provides insight into the physiological and molecular mechanisms underlying As uptake and translocation in rice plants under different water regimes, which will be helpful for adopting the irrigation technique to mitigate excessive As accumulation in rice grains and associated health risk to humans.


Assuntos
Irrigação Agrícola/métodos , Arsênico/metabolismo , Proteínas de Membrana Transportadoras/genética , Oryza/metabolismo , Poluentes do Solo/metabolismo , Compostos de Sulfidrila/metabolismo , Poluentes Químicos da Água/metabolismo , Arsênico/análise , Disponibilidade Biológica , Transporte Biológico , Ácido Cacodílico/metabolismo , Grão Comestível/genética , Grão Comestível/metabolismo , Humanos , Ferro/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Oryza/genética , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Rizosfera , Solo/química , Poluentes do Solo/análise , Poluentes Químicos da Água/análise
6.
Artigo em Inglês | MEDLINE | ID: mdl-32656654

RESUMO

Nitric oxide (NO) being a signaling molecule inside the plant cells, play significant role in signaling cascades and protection against environmental stresses. However, the protective role of NO in alleviating As toxicity in rice plants is currently not available. In the present study, the level of NO, nitrogen (N), inorganic N (nitrate, ammonium), thiols {TT (Total thiols), NPT (Nonprotein thiol)} and AAs contents along with N assimilating enzymes (NR, GDH, GOGAT) were analyzed after exposure of AsIII/NO treatment alone, and in combination. NO supplementation enhanced the content of N, inorganic N & thiol contents, NR, GOGAT activities, when compared with AsIII exposure alone. In AsIII exposed rice seedlings, content of AAs (except His, Arg, Met) reduced over the control, while supplementation of SNP improved AAs contents, compared to AsIII treatment alone. In conclusion, rice seedlings supplemented with NO tolerate the AsIII toxicity by reducing the N related parameters, thiol contents, altering the AA profile and enhanced the nutritional quality by increasing EAAs (essential amino acids) and NEAAs (non-essential amino acids).


Assuntos
Aminoácidos/metabolismo , Arsênico/efeitos adversos , Óxido Nítrico/metabolismo , Nitrogênio/metabolismo , Oryza/metabolismo , Poluentes do Solo/efeitos adversos , Compostos de Sulfidrila/metabolismo , Relação Dose-Resposta a Droga , Glutationa/metabolismo , Óxido Nítrico/administração & dosagem , Oryza/efeitos dos fármacos , Estresse Fisiológico
7.
Sci Rep ; 10(1): 12500, 2020 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-32719469

RESUMO

Body odour is a characteristic trait of Homo sapiens, however its role in human behaviour and evolution is poorly understood. Remarkably, body odour is linked to the presence of a few species of commensal microbes. Herein we discover a bacterial enzyme, limited to odour-forming staphylococci that are able to cleave odourless precursors of thioalcohols, the most pungent components of body odour. We demonstrated using phylogenetics, biochemistry and structural biology that this cysteine-thiol lyase (C-T lyase) is a PLP-dependent enzyme that moved horizontally into a unique monophyletic group of odour-forming staphylococci about 60 million years ago, and has subsequently tailored its enzymatic function to human-derived thioalcohol precursors. Significantly, transfer of this enzyme alone to non-odour producing staphylococci confers odour production, demonstrating that this C-T lyase is both necessary and sufficient for thioalcohol formation. The structure of the C-T lyase compared to that of other related enzymes reveals how the adaptation to thioalcohol precursors has evolved through changes in the binding site to create a constrained hydrophobic pocket that is selective for branched aliphatic thioalcohol ligands. The ancestral acquisition of this enzyme, and the subsequent evolution of the specificity for thioalcohol precursors implies that body odour production in humans is an ancient process.


Assuntos
Álcoois/metabolismo , Corpo Humano , Odorantes/análise , Compostos de Sulfidrila/metabolismo , Álcoois/química , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Teorema de Bayes , Sítios de Ligação , Liases de Carbono-Enxofre/química , Liases de Carbono-Enxofre/metabolismo , Cisteína/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Modelos Moleculares , Filogenia , Staphylococcus/metabolismo , Compostos de Sulfidrila/química , Fatores de Tempo
8.
J Med Chem ; 63(21): 12460-12484, 2020 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-32608981

RESUMO

It is now 30 years since the first report of a potent zinc-dependent histone deacetylase (HDAC) inhibitor appeared. Since then, five HDAC inhibitors have received regulatory approval for cancer chemotherapy while many others are in clinical development for oncology as well as other therapeutic indications. This Perspective reviews the biological and medicinal chemistry advances over the past 3 decades with an emphasis on the design of selective inhibitors that discriminate between the 11 human HDAC isoforms.


Assuntos
Inibidores de Histona Desacetilases/química , Histona Desacetilases/metabolismo , Anilidas/química , Anilidas/metabolismo , Anilidas/uso terapêutico , Produtos Biológicos/química , Produtos Biológicos/metabolismo , Produtos Biológicos/uso terapêutico , Ensaios Clínicos como Assunto , Inibidores de Histona Desacetilases/metabolismo , Inibidores de Histona Desacetilases/uso terapêutico , Histona Desacetilases/química , Humanos , Ácidos Hidroxâmicos/química , Ácidos Hidroxâmicos/metabolismo , Ácidos Hidroxâmicos/uso terapêutico , Isoenzimas/antagonistas & inibidores , Isoenzimas/metabolismo , Linfoma/tratamento farmacológico , Linfoma/patologia , Compostos de Sulfidrila/química , Compostos de Sulfidrila/metabolismo , Compostos de Sulfidrila/uso terapêutico
9.
Sci Rep ; 10(1): 10193, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32576894

RESUMO

Phytohormones, such as auxins and cytokinins, take part in the integration of growth control and stress response, but their role in algal adaptation to heavy metal remains to be elucidated. The current research indicated that lead (Pb), one of the most toxic metals in nature, causes severe depletion of endogenous cytokinins, auxins, and gibberellin and an increase in abscisic acid content in the green alga Acutodesmus obliquus. Exogenous auxins and cytokinins alleviate Pb toxicity through the regulation of the endogenous phytohormones' levels. Exogenously applied auxins provoked the coordinated activation metal tolerance mechanisms leading to the increase in phytochelatin synthase activity and accumulation of phytochelatins and their precursors, which are essential for Pb sequestration. On the other hand, phytochelatin synthesis decreased in algal cells treated with cytokinins. Significant changes in the levels of low molecular weight metabolites, mainly involved in metal chelation and glutathione synthesis pathway under the influence of phytohormones in algal cells growing in the presence of Pb stress, were observed. This is the first report showing that auxins and cytokinins are important regulatory factors in algal adaptation strategies to heavy metal stress based on thiol-mediated compounds and the maintenance of phytohormone homeostasis.


Assuntos
Clorofíceas/metabolismo , Clorófitas/metabolismo , Citocininas/metabolismo , Homeostase/fisiologia , Ácidos Indolacéticos/metabolismo , Chumbo/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Compostos de Sulfidrila/metabolismo , Adaptação Fisiológica/fisiologia , Fitoquelatinas/metabolismo
10.
Chem Biol Interact ; 327: 109166, 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-32531310

RESUMO

Boldine is the main alkaloid of Peumus boldus Molina, widely used in the traditional medicine for the treatment of digestive disorders. It is a compound with excellent antioxidant and anti-inflammatory properties already described. Despite the widespread use of P. boldus for digestive disorders treatment, the gastroprotective effect of Boldine remains unknown. Considering the need for new approaches to treat gastric ulcers with fewer side effects than current therapy, this study aimed to investigate the gastroprotective effect of Boldine in mice, as well as the mechanisms underlying this effect. The gastroprotective effect of Boldine was evaluated on gastric ulcer induced by 60% ethanol/0.3 M HCl or indomethacin (100 mg/kg) in mice. Histological analysis and the mucin-like glycoprotein content were evaluated in ethanol-ulcerated tissue, as well as, oxidative stress and inflammatory parameters. The mechanisms involved in the effect of Boldine were evaluated by pretreating mice with NEM (a sulfhydryl group chelator, 10 mg/kg, i.p.), l-NAME (a non-selective nitric oxide synthase inhibitor, 70 mg/kg, i.p.), yohimbine (an alpha-adrenergic receptor antagonist, 2 mg/kg, i.p.) and indomethacin (a cyclooxygenase inhibitor, 10 mg/kg, i.p.). In addition, the in vitro effect of Boldine on H+/K+-ATPase activity was determined. Boldine was able to protect gastric mucosa against the damage induced by ethanol/HCl and indomethacin, as evidenced by reduced lesion area and histological analysis. Moreover, the alkaloid reduced oxidative stress and inflammatory mediators in ethanol-ulcerated tissue, beyond has increased mucin-like glycoprotein amount. Finally, Boldine effect is dependent on non-protein sulfhydryl groups and prostanoids but does not involve the inhibition of H+/K + -ATPase activity, being a promising natural resource for gastric ulcer treatment.


Assuntos
Antiulcerosos/farmacologia , Aporfinas/farmacologia , Mucosa Gástrica/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Úlcera Gástrica/prevenção & controle , Animais , Etanol , Feminino , Mucosa Gástrica/patologia , ATPase Trocadora de Hidrogênio-Potássio/metabolismo , Indometacina , Inflamação/induzido quimicamente , Inflamação/prevenção & controle , Peroxidação de Lipídeos/efeitos dos fármacos , Camundongos , Prostaglandinas/metabolismo , Coelhos , Úlcera Gástrica/induzido quimicamente , Compostos de Sulfidrila/metabolismo
11.
J Agric Food Chem ; 68(27): 7184-7193, 2020 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-32539383

RESUMO

3-Mercaptocycloalkanones and 3-mercaptocycloalkanols (chain lengths C5-C7) were obtained by addition of thioacetic acid to the respective 2-cycloalken-1-ones and subsequent enzyme-mediated hydrolysis and reduction with LiAlH4, respectively. The stereoisomers were separated via capillary gas chromatography using chiral stationary phases. Their configurations were determined based on 1H NMR data and enzyme-catalyzed kinetic resolutions. Odor thresholds and odor qualities were assessed by capillary gas chromatography/olfactometry. Compared to the analogous acyclic 4-mercapto-2-alkanones and 4-mercapto-2-alkanols, the cyclic polyfunctional thiols lacked fruity, tropical notes; the perceived odor properties ranged from cooked, roasted vegetables and meat types to onion-related notes. The odor thresholds of the enantiomers of the 3-mercaptocycloalkanones were mainly impacted by their ring size rather than their configuration. For the 3-mercaptocycloalkanols, the (S)-configuration at the stereogenic center bearing the thiol group and the relative configuration of the second asymmetric center with the hydroxyl group were of importance for low odor thresholds.


Assuntos
Cicloparafinas/química , Compostos de Sulfidrila/química , Compostos Orgânicos Voláteis/química , Adulto , Cicloparafinas/metabolismo , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estrutura Molecular , Odorantes/análise , Olfatometria , Olfato , Estereoisomerismo , Compostos de Sulfidrila/metabolismo , Compostos Orgânicos Voláteis/metabolismo
12.
Ecotoxicol Environ Saf ; 201: 110805, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32540618

RESUMO

Screening new accumulators of heavy metal and identifying their tolerance, enrichment capacity of heavy metals are currently hot issues in phytoremediation research. A series of hydroponic experiments were conducted to analyze the effects of glutathione and phytochelatins in roots, stems, and leaves of Perilla frutescens under cadmium stress. The results showed that the non-protein thiols in roots and stems mainly existed in the form of GSH, PC2, PC3, and PC4 under Cd stress condition, while in leaves they existed in the form of GSH, PC2, and PC3. Furthermore, the contents of GSH and PCs positively correlated with Cd, but negatively correlated with root vigor and chlorophyll content under Cd stress conditions. After 21 days of treatments, the contents of Cd in different parts of the plant were 1465.2-3092.9 mg· kg-1 in the roots, 199.6-478.4 mg·kg-1 in the stems and 61.3-96.9 mg· kg-1 in the leaves at 2, 5, 10 mg·L-1 Cd levels respectively, and the amount of Cd uptakes were up to 3547.7-5701.7 µg·plant-1. Therefore, P. frutescens performed high capacity in Cd accumulation, and PCs played a key role in Cd tolerance. The application prospect of the plant in phytoremediation Cd polluted soil was also discussed.


Assuntos
Cádmio/toxicidade , Glutationa/biossíntese , Estresse Oxidativo/efeitos dos fármacos , Perilla frutescens/metabolismo , Fitoquelatinas/biossíntese , Poluentes do Solo/toxicidade , Biodegradação Ambiental , Cádmio/metabolismo , Clorofila/metabolismo , Perilla frutescens/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Solo/química , Poluentes do Solo/metabolismo , Compostos de Sulfidrila/metabolismo
13.
Sci Rep ; 10(1): 10177, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32576932

RESUMO

Stromal interaction molecule-1 and -2 (STIM1/2) are endoplasmic reticulum (ER) membrane-inserted calcium (Ca2+) sensing proteins that, together with Orai1-composed Ca2+ channels on the plasma membrane (PM), regulate intracellular Ca2+ levels. Recent evidence suggests that S-nitrosylation of the luminal STIM1 Cys residues inhibits store operated Ca2+ entry (SOCE). However, the effects of thiol modifications on STIM2 during nitrosative stress and their role in regulating basal Ca2+ levels remain unknown. Here, we demonstrate that the nitric oxide (NO) donor nitrosoglutathione (GSNO) thermodynamically stabilizes the STIM2 Ca2+ sensing region in a Cys-specific manner. We uncovered a remarkable synergism in this stabilization involving the three luminal Cys of STIM2, which is unique to this paralog. S-Nitrosylation causes structural perturbations that converge on the face of the EF-hand and sterile α motif (EF-SAM) domain, implicated in unfolding-coupled activation. In HEK293T cells, enhanced free basal cytosolic Ca2+ and SOCE mediated by STIM2 overexpression could be attenuated by GSNO or mutation of the modifiable Cys located in the luminal domain. Collectively, we identify the Cys residues within the N-terminal region of STIM2 as modifiable targets during nitrosative stress that can profoundly and cooperatively affect basal Ca2+ and SOCE regulation.


Assuntos
Cálcio/metabolismo , Membrana Celular/metabolismo , Glutationa/metabolismo , Molécula 2 de Interação Estromal/metabolismo , Compostos de Sulfidrila/metabolismo , Sinalização do Cálcio/fisiologia , Linhagem Celular , Retículo Endoplasmático/metabolismo , Células HEK293 , Humanos , Proteínas de Membrana/metabolismo , Proteína ORAI1/metabolismo , Ligação Proteica/fisiologia , Molécula 1 de Interação Estromal/metabolismo
14.
Nucleosides Nucleotides Nucleic Acids ; 39(8): 1108-1121, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32449465

RESUMO

Promutagenic O6-alkylguanine adducts in DNA are repaired in humans by O6-methylguanine-DNA-methyltransferase (MGMT) in an irreversible reaction. Here we describe the synthesis of a phosphoramidite that allows the preparation of oligodeoxyribonucleotides (ODNs) containing a novel tricyclic thio analogue of O6-methylguanine in which the third ring bridges the 6-thio group and C7 of a 7-deazapurine. These ODNs are very poor substrates for MGMT and poorly recognised by the alkyltransferase-like protein, Atl1. Examination of the active sites of both MGMT and Atl1 suggest large steric clashes hindering binding of the analogue. Such analogues, if mutagenic, are likely to be highly toxic.


Assuntos
Alquil e Aril Transferases/química , Guanina/análogos & derivados , O(6)-Metilguanina-DNA Metiltransferase/química , Oligodesoxirribonucleotídeos/química , Compostos de Sulfidrila/química , Alquil e Aril Transferases/metabolismo , Guanina/química , Guanina/metabolismo , Humanos , Modelos Moleculares , Estrutura Molecular , O(6)-Metilguanina-DNA Metiltransferase/metabolismo , Oligodesoxirribonucleotídeos/síntese química , Oligodesoxirribonucleotídeos/metabolismo , Compostos de Sulfidrila/metabolismo
15.
Inorg Chem ; 59(12): 8034-8043, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32452669

RESUMO

Cytochrome (Cyt) P450s are an important class of enzymes with numerous functions in nature. The unique reactivity of these enzymes relates to their heme b active sites with an axially bound, deprotonated cysteine (a "cysteinate") ligand (chemically speaking a thiolate). The heme-thiolate active sites further contain a number of conserved hydrogen-bonds (H-bonds) to the bound cysteinate ligand, which have been proposed to tune and stabilize the Fe-S bond. In this work, we present the low-temperature preparation of five ferric heme-thiolate nitric oxide (NO) model complexes that contain one tunable hydrogen-bond to the bound thiolate ligand. We show that the presence of a H-bond has a dramatic effect in stabilizing the thiolate ligand against direct reaction with NO. This observation reinforces the important protective role of H-bonds in Cyt P450s. We further demonstrate that H-bond strength tunes thiolate donor strength, which, in turn, controls the N-O and Fe-NO stretching frequencies and hence, bond strengths. We observe a direct correlation between the Fe-NO and N-O stretching frequencies, indicative of a thiolate σ-trans effect (interaction). Here, very small changes in H-bond strength lead to a surprisingly large effect on the FeNO unit. This result implies that subtle changes in the Cys-pocket of a Cyt P450 can strongly affect reactivity. Importantly, using the Fe-NO/N-O correlation established here, the thiolate donor strength in heme-thiolate enzyme active sites and model complexes can be quantified in a straightforward way, using NO as a probe. This spectroscopic correlation provides a quantitative measure of the thiolate's "push" effect, which is important in O2-activation (Compound I formation) in Cyt P450s in general.


Assuntos
Sistema Enzimático do Citocromo P-450/química , Compostos Férricos/química , Modelos Químicos , Compostos de Sulfidrila/química , Sistema Enzimático do Citocromo P-450/metabolismo , Teoria da Densidade Funcional , Compostos Férricos/metabolismo , Ligação de Hidrogênio , Compostos de Sulfidrila/metabolismo
16.
Biochem J ; 477(10): 1865-1878, 2020 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-32463881

RESUMO

The antagonism between thiol oxidation and reduction enables efficient control of protein function and is used as central mechanism in cellular regulation. The best-studied mechanism is the dithiol-disulfide transition in the Calvin Benson Cycle in photosynthesis, including mixed disulfide formation by glutathionylation. The adjustment of the proper thiol redox state is a fundamental property of all cellular compartments. The glutathione redox potential of the cytosol, stroma, matrix and nucleoplasm usually ranges between -300 and -320 mV. Thiol reduction proceeds by short electron transfer cascades consisting of redox input elements and redox transmitters such as thioredoxins. Thiol oxidation ultimately is linked to reactive oxygen species (ROS) and reactive nitrogen species (RNS). Enhanced ROS production under stress shifts the redox network to more positive redox potentials. ROS do not react randomly but primarily with few specific redox sensors in the cell. The most commonly encountered reaction within the redox regulatory network however is the disulfide swapping. The thiol oxidation dynamics also involves transnitrosylation. This review compiles present knowledge on this network and its central role in sensing environmental cues with focus on chloroplast metabolism.


Assuntos
Cloroplastos/metabolismo , Estresse Oxidativo/fisiologia , Fotossíntese/fisiologia , Plantas/metabolismo , Compostos de Sulfidrila/metabolismo , Dissulfetos/metabolismo , Glutationa/metabolismo , Oxirredução , Espécies Reativas de Nitrogênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Estresse Fisiológico , Tiorredoxinas/metabolismo
17.
Sci Rep ; 10(1): 6900, 2020 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-32327685

RESUMO

In this study, Ca2+ mediated NO signalling was studied in response to metalloid (As) stress in Brassica seedlings. Arsenic toxicity strongly suppressed the growth (fresh weight, root and shoot length), photosynthetic pigments, Chl a fluorescence indices (Kinetic traits: Fv, Fm, Fv/Fo, Fm/Fo, ФPo or Fv/Fm, Ψo, ФEo, PIABS, Area and N and redox status (AsA/DHA and GSH/GSSG ratios) of the cell; whereas energy flux traits: ABS/RC, TRo/RC, ETo/RC and DIo/RC along with Fo, Fo/Fv, Fo/Fm, ФDo and Sm) were enhanced. Further, addition of EGTA (Ca2+ scavenger) and LaCl3 (plasma membrane Ca2+ channel blocker) to As + Ca; while c‒PTIO (NO scavenger) and L‒NAME (NO synthase inhibitor) to As + SNP treated seedlings, siezed recovery on above parameters caused due to Ca2+ and NO supplementation, respectively to As stressed seedlings thereby indicating their signalling behaviour. Further, to investigate the link between Ca2+ and NO, when c‒PTIO and L‒NAME individually as well as in combination were supplemented to As + Ca treated seedlings; a sharp inhibition in above mentioned traits was observed even in presence of Ca2+, thereby signifying that NO plays crucial role in Ca2+ mediated signalling. In addition, As accumulation, ROS and their indices, antioxidant system, NO accumulation and thiol compounds were also studied that showed varied results.


Assuntos
Arsênico/toxicidade , Cálcio/metabolismo , Mostardeira/crescimento & desenvolvimento , Óxido Nítrico/metabolismo , Plântula/crescimento & desenvolvimento , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Carotenoides/metabolismo , Clorofila/metabolismo , Eletrólitos/metabolismo , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Mostardeira/efeitos dos fármacos , Nitroprussiato/farmacologia , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Fenótipo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Plântula/efeitos dos fármacos , Compostos de Sulfidrila/metabolismo , Superóxidos/metabolismo
18.
Food Chem ; 322: 126754, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32283367

RESUMO

During storage of coffee, the key aroma 2-furfurylthiol becomes less active, the mechanisms of this loss and ways to mitigate it were investigated. Aroma profiles were analyzed using GC-MS and sensory properties were evaluated by Quantitative Descriptive Analysis. Quinones, as the oxidation products of hydroxydroquinone, was found to actively bind 2-furfurylthiol, which accounted for the loss of 2-furfurylthiol. To mitigate this loss, ingredients were screened for their ability to prevent 2-furfurylthiol from loss. Cysteine had the highest 2-furfurylthiol releasing efficiency and ascorbic acid was also selected due to its 2-furfurylthiol releasing ability in Fenton reaction system. Concentrations were optimized and the addition of 0.045 g/L cysteine and 0.05 g/L ascorbic acid directly protected aroma during storage, these included 2-furfurylthiol, dimethyltrisulfide, methyl furfuryl disulfide, 4-ethylguaiacol and 4-vinylguaiacol. Ultimately, sensory testing showed a direct enhancement in nutty, sulfurous and roasted aroma attributes, an increase in flavour intensity and preference over shelf life.


Assuntos
Café/química , Furanos/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Compostos de Sulfidrila/metabolismo , Compostos Orgânicos Voláteis/análise , Ácido Ascórbico/química , Café/metabolismo , Culinária/métodos , Cisteína/química , Armazenamento de Alimentos , Furanos/química , Análise dos Mínimos Quadrados , Quinonas/química , Quinonas/metabolismo , Compostos de Sulfidrila/química , Paladar , Compostos Orgânicos Voláteis/química
19.
Sensors (Basel) ; 20(6)2020 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-32245186

RESUMO

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.


Assuntos
Transferência Ressonante de Energia de Fluorescência/métodos , Mitocôndrias/metabolismo , Compostos de Sulfidrila/metabolismo , Corantes Fluorescentes , Glutationa/química , Células HeLa , Humanos , Naftalimidas/química , Imagem Óptica , Rodaminas/química
20.
J Sci Food Agric ; 100(7): 3262-3268, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32086798

RESUMO

BACKGROUND: Over recent years, a new wave of disease-tolerant to mildew varieties has flooded the viticulture sector, for reasons of human safety and economic expediency. These hybrid grape cultivars are selected mainly on the basis of their intrinsic capability to counter the attack of the main fungal diseases that affect grape production, such as downy mildew and powdery mildew. However, their organoleptic and oenological characteristics have not yet been studied in depth for purposes of both juice and wine production, due to the high number of newly proposed germplasms and the lack of information about their adaptability to different environments. This work examines the thiol aroma precursors concentration in 64 red and white disease-tolerant hybrid varieties in the vine germplasm collections of Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria-Viticulture and Enology Research Center and Fondazione Edmund Mach, both from the north-east of Italy. RESULTS: All cultivars showed the presence of 3-mercaptohexan-1-ol (3MH) precursors, ranging from 4.4 to 1141 µg kg-1 for 3-S-glutathionyl hexan-1-ol (GSH-3MH), and from 0.3 to 136 µg kg-1 for 3-S-cysteinyl 3-hexan-1-ol. The concentration of GSH-3MH exceeded 600 µg kg-1 in eight varieties, with values comparable to those of the richest Vitis vinifera reported so far. On average, red grapes showed higher concentrations of 3MH precursors than white ones did. Only two hybrids had 4-mercapto-4-methylpentan-2-one (4MMP) precursors over the limit of quantification, albeit with a much higher concentration than those normally reported in Sauvignon Blanc. CONCLUSION: This is the first detailed survey of 3MH and 4MMP precursors carried out taking into account a considerable number of hybrid grape varieties. The results show that some of these varieties could be interesting for the production of tropical juices or tropical-aromatic wines and soft drinks, through the enzymatic liberation of thiol aromas, as well as for the production of aromatizing tannins to be used in the food industry. © 2020 Society of Chemical Industry.


Assuntos
Compostos de Sulfidrila/análise , Vitis/química , Fungos/fisiologia , Itália , Odorantes/análise , Doenças das Plantas/microbiologia , Compostos de Sulfidrila/metabolismo , Vitis/classificação , Vitis/metabolismo , Vitis/microbiologia , Vinho/análise , Vinho/microbiologia
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