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https://www.readbyqxmd.com/read/29776001/evidence-for-formation-of-a-radical-mediated-flavin-n5-covalent-intermediate
#1
Yumin Dai, Hannah R Valentino, Pablo Sobrado
The redox-neutral reaction catalyzed by 2-haloacrylate hydratase (2-HAH) leads to the conversion of 2-chloroacrylate to pyruvate. Previous mechanistic studies demonstrated formation of a flavin-iminium ion as an important intermediate in the 2-HAH catalytic cycle. Time-resolved flavin absorbance studies were performed in this study and the data showed that the enzyme is capable of stabilizing both anionic and neutral flavin semiquinone species. The presence of a radical scavenger decreases the activity in a concentration-dependent manner...
May 18, 2018: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/29775963/brain-ischemic-preconditioning-protects-against-ischemic-injury-and-preserves-the-blood-brain-barrier-via-oxidative-signaling-and-nrf2-activation
#2
Tuo Yang, Yang Sun, Leilei Mao, Meijuan Zhang, Qianqian Li, Lili Zhang, Yejie Shi, Rehana K Leak, Jun Chen, Feng Zhang
Brain ischemic preconditioning (IPC) with mild ischemic episodes is well known to protect the brain against subsequent ischemic challenges. However, the underlying mechanisms are poorly understood. Here we demonstrate the critical role of the master redox transcription factor, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), in IPC-mediated neuroprotection and blood-brain barrier (BBB) preservation. We report that IPC causes generation of endogenous lipid electrophiles, including 4-hydroxy-2-nonenal (4-HNE), which release Nrf2 from inhibition by Keap1 (via Keap1-C288) and inhibition by glycogen synthase kinase 3β (via GSK3β-C199)...
May 6, 2018: Redox Biology
https://www.readbyqxmd.com/read/29775962/preterm-birth-and-oxidative-stress-effects-of-acute-physical-exercise-and-hypoxia-physiological-responses
#3
Agnès Martin, Camille Faes, Tadej Debevec, Chantal Rytz, Grégoire Millet, Vincent Pialoux
Preterm birth is a global health issue that can induce lifelong medical sequela. Presently, at least one in ten newborns are born prematurely. At birth, preterm newborns exhibit higher levels of oxidative stress (OS) due to the inability to face the oxygen rich environment in which they are born into. Moreover, their immature respiratory, digestive, immune and antioxidant defense systems, as well as the potential numerous medical interventions following a preterm birth, such as oxygen resuscitation, nutrition, phototherapy and blood transfusion further contribute to high levels of OS...
May 1, 2018: Redox Biology
https://www.readbyqxmd.com/read/29775961/antioxidant-response-elements-discovery-classes-regulation-and-potential-applications
#4
REVIEW
Azhwar Raghunath, Kiruthika Sundarraj, Raju Nagarajan, Frank Arfuso, Jinsong Bian, Alan P Kumar, Gautam Sethi, Ekambaram Perumal
Exposure to antioxidants and xenobiotics triggers the expression of a myriad of genes encoding antioxidant proteins, detoxifying enzymes, and xenobiotic transporters to offer protection against oxidative stress. This articulated universal mechanism is regulated through the cis-acting elements in an array of Nrf2 target genes called antioxidant response elements (AREs), which play a critical role in redox homeostasis. Though the Keap1/Nrf2/ARE system involves many players, AREs hold the key in transcriptional regulation of cytoprotective genes...
May 7, 2018: Redox Biology
https://www.readbyqxmd.com/read/29775930/synthesis-photophysical-and-electrochemical-properties-of-a-blue-emitter-with-binaphthalene-and-carbazole-units
#5
Lixia Guo, Xiaoju Wang, Liheng Feng
A blue emitter, 3,3'-(2,2'-dimethoxy-[1,1'-binaphthalene]-6,6'-diyl)bis(9-benzyl-9H-carbazole), was synthesized by Suzuki coupling reaction. The photophysical properties of the emitter in solution were firstly investigated by UV-Vis absorption and fluorescence emission techniques. The results indicate that the emitter has excellent optical and electron transfer properties. The maximum absorption and emission peaks of the emitter are 302 nm and 406 nm with 67.4% fluorescence quantum yield in chloroform, respectively...
May 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29775743/redox-regulation-of-protein-kinase-c-by-selenometabolites-and-selenoprotein-thioredoxin-reductase-limits-cancer-prevention-by-selenium
#6
REVIEW
Rayudu Gopalakrishna, Usha Gundimeda, Sarah Zhou, Bui Helena, Arne Holmgren
The cancer-preventive mechanism of selenium should address the way low concentrations of selenometabolites react with cellular targets without being diffused from the sites of generation, the way selenium selectively kills tumor cells, and the intriguing U-shaped curve that is seen with dietary supplementation of selenium and cancer prevention. Protein kinase C (PKC), a receptor for tumor promoters, is well suited for this mechanism. Due to the catalytic redox cycle, low concentrations of methylselenol, a postulated active metabolite of selenium, react with the tumor-promoting lipid hydroperoxide bound to PKC to form methylseleninic acid (MSA), which selectively reacts with thiol residues present within the vicinity of the PKC catalytic domain to inactivate it...
May 15, 2018: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/29775742/ryanodine-receptor-ca-2-release-channel-post-translational-modification-central-player-in-cardiac-and-skeletal-muscle-disease
#7
Amanda Denniss, Angela F Dulhunty, Nicole A Beard
Calcium release from internal stores is a quintessential event in excitation-contraction coupling in cardiac and skeletal muscle. The ryanodine receptor Ca2+ release channel is embedded in the internal sarcoplasmic reticulum Ca2+ store, which releases Ca2+ into the cytoplasm, enabling contraction. Ryanodine receptors form the hub of a macromolecular complex extending from the extracellular space to the sarcoplasmic reticulum lumen. Ryanodine receptor activity is influenced by the integrated effects of associated co-proteins, ions, and post-translational phosphor and redox modifications...
May 15, 2018: International Journal of Biochemistry & Cell Biology
https://www.readbyqxmd.com/read/29775644/redox-signal-mediated-trpm2-promotes-ang-ii-induced-adipocyte-insulin-resistance-via-ca-2-dependent-camkii-jnk-cascade
#8
Min Gao, Yu Du, Jing-Wen Xie, Jing Xue, Yi-Ting Wang, Li Qin, Ming-Ming Ma, Yong-Bo Tang, Xiao-Yan Li
BACKGROUND AND OBJECTIVE: Redox-sensitive transient receptor potential melastatin 2 (TRPM2) is a Ca2+ -permeable, nonselective cation channel which plays a crucial role in various physiological processes. However, little is known whether TRPM2 is involved in adipocyte dysfunction during hypertension. In the present study, we determined the role of TRPM2 in angiotensin II (Ang II)-induced insulin resistance in adipocytes and the underlying mechanisms. METHODS: Ang II-induced adipocyte insulin resistant model was conducted...
May 15, 2018: Metabolism: Clinical and Experimental
https://www.readbyqxmd.com/read/29775569/modification-of-chickpea-cystatin-by-reactive-dicarbonyl-species-glycation-oxidation-and-aggregation
#9
Sheraz Ahmad Bhat, Waseem Feeroze Bhat, Mohammad Afsar, Mohd Shahnawaz Khan, Bilqees Bano
Reactive dicarbonyl species such as methylglyoxal (MGO) and glyoxal (GO) have recently received extensive attention due to their high reactivity and ability to modify biological substances such as proteins, phospholipids, and DNA. In case of proteins these reactive species mainly react with lysine and arginine residues to form AGEs, oxidative products, and aggregates. Chickpea cystatin (CPC) was incubated with varying concentrations of glyoxal and methylglyoxal which caused, along with altered secondary and tertiary structures, glycation, functional inactivation, altered redox state, cross-linking and high-molecular-mass aggregation...
May 15, 2018: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/29775499/synthesis-spectroscopic-characterization-and-redox-reactivity-of-a-cyclic-alkyl-amino-carbene-derived-arsamethine-cyanine-dye
#10
Kortney M Melancon, M Brenton Gildner, Todd W Hudnall
In our efforts to prepare a diarsenic allotrope supported by two cyclic alkyl amino carbene (CAAC) ligands we stumbled upon the serendipitous synthesis of the first carbene-supported chloroarsinidene 3 which has been fully characterized by a combination of NMR spectroscopic and XRD methods. Although further reduction of 3 was not possible, we found that addition of a second equivalent of CAAC in refluxing toluene afforded the first example of a crystallographically characterized arsamethine cyanine dye (4)...
May 18, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29775067/rhodium-iii-catalyzed-redox-neutral-synthesis-of-isoquinolinium-salts-via-c-h-activation-of-imines
#11
Miaomiao Tian, Guangfan Zheng, Xuesen Fan, Xingwei Li
Redox-neutral synthesis of isoquinolinium salts via C-H activation of pre-synthesized or in situ formed imines and coupling with α-diazo ketoesters have been realized, where a zinc salt promotes cyclization as well as provides a counter anion. Under three-component conditions, both ketone and aldehydes are viable arene sources. The coupling of imines with diazo malonates under similar conditions afforded isoquinolin-3-ones as the coupling product.
May 18, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29775045/in-situ-spectroelectrochemical-monitoring-of-dye-bleaching-after-electrogeneration-of-chlorine-based-species-application-to-chloride-detection
#12
Daniel Martín-Yerga, Alejandro Pérez-Junquera, María Begoña Gonzalez-Garcia, David Hernández-Santos, Pablo Fanjul-Bolado
Spectroelectrochemical techniques are becoming increasingly versatile tools to solve a diverse range of analytical problems. Herein, the use of in situ real-time luminescence spectroelectrochemistry to quantify chloride ions is demonstrated. Utilizing the bleaching effect of chlorine-based electrogenerated products after chloride oxidation, it is shown that the fluorescence of the Rhodamine 6G dye decrease proportionally to the initial chloride concentration in solution. A strong decrease of fluorescence is observed in acidic media compared to a lower decrease in alkaline media, which suggests that Cl2 , favourably generated at low pH, could be the main species responsible of the fluorescence loss...
May 18, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29774976/stimuli-responsive-organic-dyes-with-tropylium-chromophore
#13
Demelza Lyons, Reece Crocker, Thanh Vinh Nguyen
Tropylium ions possess an interesting combination of structural stability and chemical reactivity due to its Hückel-aromaticity and its positively charged polyene nature, respectively. Herein we exploit the chemical versatility and unique structural properties of the tropylium ion to derive a family of novel 'push-and-pull' organic dyes with strong absorption in the visible range via simple and practical synthetic protocols. These stable organic dyes are highly stimuli-responsive, as demonstrated by their sensitivity towards solvent, pH change, redox reaction, Lewis base and counterion, which marks them as potentially useful compounds for opto-electronic applications...
May 18, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29774663/dual-responsive-carbon-dot-for-ph-redox-triggered-fluorescence-imaging-with-controllable-photothermal-ablation-therapy-of-cancer
#14
Cheong A Choi, Jung Eun Lee, Zihnil Adha Islamy Mazrad, Young Kwang Kim, Insik In, Ji Hoon Jeong, Sung Young Park
We described fluorescence resonance energy transfer for pH/redox-activatable fluorescent carbon dot (FNP) to realize "off-on" switched imaging-guided controllable photothermal therapy (PTT). The FNP is a carbonized self-crosslinked polymer that allows IR825 loading (FNP[IR825]) via hydrophobic interactions in cancer therapy. The capability for fluorescence bioimaging was achieved via the internalization of FNP(IR825) into tumor cells, wherein glutathione (GSH) disulfide bonds were reduced and benzoic imine were cleaved under acidic conditions...
May 18, 2018: ChemMedChem
https://www.readbyqxmd.com/read/29774604/plant-sunscreen-and-co-ii-iii-porphyrins-for-uv-resistant-and-thermally-stable-perovskite-solar-cells-from-natural-to-artificial
#15
Jing Cao, Xudong Lv, Peng Zhang, Tracy T Chuong, Binghui Wu, Xiaoxia Feng, Changfu Shan, Jiacheng Liu, Yu Tang
The poor UV, thermal, and interfacial stability of perovskite solar cells (PSCs) makes it highly challenging for their technological application, and has drawn increasing attention to resolving the above issues. In nature, plants generally sustain long exposure to UV illumination without damage, which is attributed to the presence of the organic materials acting as sunscreens. Inspired by the natural phenomenon, a natural plant sunscreen, sinapoyl malate, an ester derivative of sinapic acid, is employed to modify the surface of electron transport materials (ETMs)...
May 17, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29774235/the-redox-filter-beneath-magmatic-orogens-and-the-formation-of-continental-crust
#16
Ming Tang, Monica Erdman, Graham Eldridge, Cin-Ty A Lee
The two most important magmatic differentiation series on Earth are the Fe-enriching tholeiitic series, which dominates the oceanic crust and island arcs, and the Fe-depleting calc-alkaline series, which dominates the continental crust and continental arcs. It is well known that calc-alkaline magmas are more oxidized when they erupt and are preferentially found in regions of thick crust, but why these quantities should be related remains unexplained. We use the redox-sensitive behavior of europium (Eu) in deep-seated, plagioclase-free arc cumulates to directly constrain the redox evolution of arc magmas at depth...
May 2018: Science Advances
https://www.readbyqxmd.com/read/29773789/light-induced-formation-of-partially-reduced-oxygen-species-limits-the-lifetime-of-photosystem-1-based-biocathodes
#17
Fangyuan Zhao, Steffen Hardt, Volker Hartmann, Huijie Zhang, Marc M Nowaczyk, Matthias Rögner, Nicolas Plumeré, Wolfgang Schuhmann, Felipe Conzuelo
Interfacing photosynthetic proteins specifically photosystem 1 (PS1) with electrodes enables light-induced charge separation processes for powering semiartificial photobiodevices with, however, limited long-term stability. Here, we present the in-depth evaluation of a PS1/Os-complex-modified redox polymer-based biocathode by means of scanning photoelectrochemical microscopy. Focalized local illumination of the bioelectrode and concomitant collection of H2 O2 at the closely positioned microelectrode provide evidence for the formation of partially reduced oxygen species under light conditions...
May 17, 2018: Nature Communications
https://www.readbyqxmd.com/read/29773670/high-%C3%AE-tocopherol-dosing-increases-lipid-metabolism-by-changing-redox-state-in-damaged-rat-gastric-mucosa-and-liver-after-ethanol-treatment
#18
Marisela Olguín-Martínez, Diego R Hernández-Espinosa, Rolando Hernández-Muñoz
Regeneration of ethanol-injured rat gastric mucosa must undergo changes in major metabolic pathways to achieve DNA replication and cell proliferation. These events are highly dependent on glucose utilization and inhibited by vitamin E (α-tocopherol) administration. Therefore, this study was aimed at assessing lipid metabolism in the gastric mucosa and ethanol-induced gastric damage and the effect of α-tocopherol administration. For this, rates of fatty acid β-oxidation and lipogenesis were tested in gastric mucosa samples...
May 17, 2018: Clinical Science (1979-)
https://www.readbyqxmd.com/read/29773177/participation-of-selenoproteins-localized-in-the-er-in-the-processes-occurring-in-this-organelle-and-in-the-regulation-of-carcinogenesis-associated-processes
#19
REVIEW
Elena Gennadyevna Varlamova
The functions performed by the ER are diverse: synthesis of steroid hormones, synthesis of proteins for the plasma membrane, lysosomes, as well as proteins meant for exocytosis, protein folding, formation of disulfide bonds, N-linked glycosylation, etc. Selenoproteins localized in this organelle are definitely involved in the processes occurring in it, and the most common of them include participation in protein degradation, regulation of ER stress and redox metabolism. ER stress has been registered in many types of cancer cells...
July 2018: Journal of Trace Elements in Medicine and Biology
https://www.readbyqxmd.com/read/29773173/gene-expression-in-adverse-reaction-to-metal-debris-around-metal-on-metal-arthroplasty-an-rna-seq-based-study
#20
Antti Pemmari, Tiina Leppänen, Erja-Leena Paukkeri, Antti Eskelinen, Teemu Moilanen, Eeva Moilanen
Joint replacement surgery is a standard treatment of advanced osteoarthritis (OA). Since 2000, cobalt-chromium (CoCr) metal-on-metal (MoM) implants were widely used in hip arthroplasties. Some patients developed "adverse reaction to metal debris" (ARMD) around the prosthesis, resulting in a need for revision surgery. In the present study, we addressed the pathogenesis of ARMD by genome-wide expression analysis. Pseudosynovial ARMD tissue was obtained from revision surgery of Articular Surface Replacement (ASR, DePuy, Warsaw, IN, USA) hip arthroplasties...
July 2018: Journal of Trace Elements in Medicine and Biology
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