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https://www.readbyqxmd.com/read/28212027/ferromagnetic-coupling-in-the-heterospin-bis-catecholato-manganese-iv-complex-with-pyridine-substituted-by-nitronyl-nitroxide
#1
Michael P Bubnov, Irina A Teplova, Eugenia A Kopylova, Konstantin A Kozhanov, Artem S Bogomyakov, Marina V Petrova, Vitaly A Morozov, Victor I Ovcharenko, Vladimir K Cherkasov
A new bis(3,6-di-tert-butyl-catecholato)manganese complex with two 4-NIT-Py ligands was synthesized and characterized [4-NIT-Py = pyridine substituted at position 4 with nitronyl-nitroxide radical, 2-(pyridin-4-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl]. X-ray diffraction indicated an octahedral environment of the manganese atom with a trans arrangement of ligands. Bonds lengths in the inner coordination core of the metal and in the chelate cycles that are representative of the charge distribution between the metal and ligands displayed a Mn(IV)(Cat(2-))2 charge distribution...
February 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28210984/effect-of-solution-ionic-strength-on-the-pka-of-the-nitroxide-ph-epr-probe-2-2-3-4-5-5-hexamethylimidazolidin-1-oxyl
#2
Kaleigh Margita, Maxim A Voinov, Alex I Smirnov
Spin probe and spin labeling Electron Paramagnetic Resonance methods are indispensable research tools for solving a wide range of bioanalytical problems-from measuring microviscosity and polarity of phase-separated liquids to oxygen concentrations in tissues. One of the emerging uses of spin probes are the studies of proton transfer-related and surface electrostatic phenomena. The latter Electron Paramagnetic Resonance methods rely on molecular probes containing an additional functionality capable of reversible ionization (protonation, in particular) in the immediate proximity to an Electron Paramagnetic Resonance-active reporter group, such as (N-O(•)) for nitroxides...
February 17, 2017: Cell Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28210728/self-initiation-of-uv-photopolymerization-reactions-using-tetrahalogenated-bisphenol-a-meth-acrylates
#3
Théophile Pelras, Wolfgang Knolle, Sergej Naumov, Katja Heymann, Olesya Daikos, Tom Scherzer
The potential of tetrachlorinated and tetrabrominated bisphenol A diacrylates and dimethacrylates for self-initiation of a radical photopolymerization was investigated. The kinetics of the photopolymerization of an acrylic model varnish containing halogenated monomers was studied by real-time FTIR spectroscopy, whereas the formation of reactive species and secondary products was elucidated by laser flash photolysis and product analysis by GC-MS after steady-state photolysis. The interpretation of the experimental data and the analysis of possible reaction pathways were assisted by quantum chemical calculations...
February 17, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28195581/cultivation-and-characterization-of-candidatus-nitrosocosmicus-exaquare-an-ammonia-oxidizing-archaeon-from-a-municipal-wastewater-treatment-system
#4
Laura A Sauder, Mads Albertsen, Katja Engel, Jasmin Schwarz, Per H Nielsen, Michael Wagner, Josh D Neufeld
Thaumarchaeota have been detected in several industrial and municipal wastewater treatment plants (WWTPs), despite the fact that ammonia-oxidizing archaea (AOA) are thought to be adapted to low ammonia environments. However, the activity, physiology and metabolism of WWTP-associated AOA remain poorly understood. We report the cultivation and complete genome sequence of Candidatus Nitrosocosmicus exaquare, a novel AOA representative from a municipal WWTP in Guelph, Ontario (Canada). In enrichment culture, Ca...
February 14, 2017: ISME Journal
https://www.readbyqxmd.com/read/28150497/characterization-of-nanocellulose-using-small-angle-neutron-x-ray-and-dynamic-light-scattering-techniques
#5
Yimin Mao, Kai Liu, Chengbo Zhan, Lihong Geng, Benjamin Chu, Benjamin S Hsiao
Nanocellulose extracted from wood pulps using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation and sulfuric acid hydrolysis methods was characterized by small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) techniques. The dimensions of this nanocellulose (TEMPO-oxidized cellulose nanofiber (TOCN) and sulfuric acid hydrolyzed cellulose nanocrystal (SACN)) revealed by the different scattering methods were compared with those characterized by transmission electron microscopy (TEM)...
February 2, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28115098/tempo-oxidized-bacterial-cellulose-nanofibers-supported-gold-nanoparticles-with-superior-catalytic-properties
#6
Yan Chen, Shiyan Chen, Baoxiu Wang, Jingjing Yao, Huaping Wang
A novel nanohybrid was successfully fabricated by deposition of gold nanoparticles (AuNPs) onto the surface of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized bacterial cellulose nanofibers (TOBCNs). The prepared AuNPs/TOBCNs nanohybrids were characterized by UV-vis spectral analysis, XRD, TEM and HRTEM. Their catalytic activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) was estimated by UV-vis spectrometry. The results showed that the AuNPs/TOBCNs nanohybrids possessed AuNPs with an average diameter of 4...
March 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28095321/cellulose-to-depolymerize%C3%A2-or-not-to
#7
REVIEW
Sergiu Coseri
Oxidation of the primary OH groups in cellulose is a pivotal reaction both at lab and industrial scale, leading to the value-added products, i.e. oxidized cellulose which have tremendous applications in medicine, pharmacy and hi-tech industry. Moreover, the introduction of carboxyl moieties creates prerequisites for further cellulose functionalization through covalent attachment or electrostatic interactions, being an essential achievement designed to boost the area of cellulose-based nanomaterials fabrication...
January 15, 2017: Biotechnology Advances
https://www.readbyqxmd.com/read/28069660/antioxidant-treatment-attenuates-lactate-production-in-diabetic-nephropathy
#8
Christoffer Laustsen, Per Mose Nielsen, Thomas Stokholm Nørlinger, Haiyun Qi, Uffe Kjærgaard Pedersen, Lotte Bonde Bertelsen, Jakob Appel Østergaard, Allan Flyvbjerg, Jan Henrik Ardenkjær-Larsen, Fredrik Palm, Hans Stødkilde-Jørgensen
The early progression of diabetic nephropathy is notoriously difficult to detect and quantify before the occurrence of substantial histological damage. Recently, hyperpolarized [1-(13)C]pyruvate has demonstrated increased lactate production in the kidney early after the onset of diabetes, implying increased lactate dehydrogenase activity as a consequence of increased nicotinamide adenine dinucleotide substrate availability due to upregulation of the polyol pathway, i.e., pseudohypoxia. In this study, we investigated the role of oxidative stress in mediating these metabolic alterations using state-of-the-art hyperpolarized magnetic resonance (MR) imaging...
January 1, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28064177/nitric-oxide-acts-upstream-of-ethylene-in-cell-wall-phosphorus-reutilization-in-phosphorus-deficient-rice
#9
Xiao Fang Zhu, Chun Quan Zhu, Chao Wang, Xiao Ying Dong, Ren Fang Shen
Nitric oxide (NO) and ethylene are both involved in cell wall phosphorus (P) reutilization in P-deficient rice; however, the crosstalk between them remains unclear. In the present study using P-deficient 'Nipponbare' (Nip), root NO accumulation significantly increased after 1 h and reached a maximum at 3 h, while ethylene production significantly increased after 3 h and reached a maximum at 6 h, indicating NO responded more quickly than ethylene. Irrespective of P status, addition of the NO donor sodium nitroprusside (SNP) significantly increased while the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) significantly decreased the production of ethylene, while neither the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) nor the ethylene inhibitor aminoethoxyvinylglycine (AVG) had any influence on NO accumulation, suggesting NO acted upstream of ethylene...
January 7, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28063096/feasibility-of-in-vivo-three-dimensional-t-2-mapping-using-dicarboxy-proxyl-and-cw-epr-based-single-point-imaging
#10
Harue Kubota, Denis A Komarov, Hironobu Yasui, Shingo Matsumoto, Osamu Inanami, Igor A Kirilyuk, Valery V Khramtsov, Hiroshi Hirata
OBJECTIVES: The aim of this study was to demonstrate the feasibility of in vivo three-dimensional (3D) relaxation time T 2(*) mapping of a dicarboxy-PROXYL radical using continuous-wave electron paramagnetic resonance (CW-EPR) imaging. MATERIALS AND METHODS: Isotopically substituted dicarboxy-PROXYL radicals, 3,4-dicarboxy-2,2,5,5-tetra((2)H3)methylpyrrolidin-(3,4-(2)H2)-(1-(15)N)-1-oxyl ((2)H,(15)N-DCP) and 3,4-dicarboxy-2,2,5,5-tetra((2)H3)methylpyrrolidin-(3,4-(2)H2)-1-oxyl ((2)H-DCP), were used in the study...
January 6, 2017: Magma
https://www.readbyqxmd.com/read/28062279/nitric-oxide-induced-synthesis-of-hydrogen-sulfide-alleviates-osmotic-stress-in-wheat-seedlings-through-sustaining-antioxidant-enzymes-osmolyte-accumulation-and-cysteine-homeostasis
#11
M Nasir Khan, M Mobin, Zahid Khorshid Abbas, Manzer H Siddiqui
Nitric oxide (NO) and hydrogen sulfide (H2S) have been shown to act as signaling molecules in various physiological processes, play significant roles in plant cellular processes, and also mediate responses to both biotic and abiotic stresses in plants. The present investigation was carried out to test the effect of exogenous NO on endogenous synthesis of H2S in osmotic-stressed wheat (Triticum aestivum L.) seedlings. The results show that application of NO to wheat seedlings, suffered from PEG8000-induced osmotic stress, considerably enhanced the activities of H2S-synthesizing enzymes l-cysteine desulfhydrase (LCD) and d-cysteine desulfhydrase (DCD) leading to enhanced level of endogenous H2S content...
January 3, 2017: Nitric Oxide: Biology and Chemistry
https://www.readbyqxmd.com/read/28052402/electron-spin-resonance-studies-on-deuterated-nitroxyl-spin-probes-used-in-overhauser-enhanced-magnetic-resonance-imaging
#12
D David Jebaraj, Hideo Utsumi, A Milton Franklin Benial
The Electron Spin Resonance studies were carried out for 2 mM concentration of (14) N and (15) N -labeled 3-carbamoyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-carboxy-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and their deuterated nitroxyl radicals using X-band Electron Spin Resonance spectrometer. The ESR Line shape analysis was carried out. The Electron Spin Resonance parameters such as, linewidth, Lorentzian component, signal intensity ratio, rotational correlation time, hyperfine coupling constant and g-factor were estimated...
January 4, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28042034/the-nitroxide-tempo-inhibits-hydroxyl-radical-production-from-the-fenton-like-reaction-of-iron-ii-citrate-with-hydrogen-peroxide
#13
Fengqiang Shi, Peifeng Zhang, Yujia Mao, Can Wang, Meiqing Zheng, Zhongwei Zhao
In vivo physiological ligand citrate can bind iron(II) ions to form the iron(II)-citrate complex. Inhibition of hydroxyl radical (OH) production from the Fenton-like reaction of iron(II)-citrate with H2O2 is biologically important, as this reaction may account for one of the mechanisms of the labile iron pool in vivo to induce oxidative stress and pathological conditions. Nitroxides have promising potentials as therapeutic antioxidants. However, there are controversial findings indicating that they not only act as antioxidants but also as pro-oxidants when engaged in Fenton reactions...
January 29, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28036163/immunosensors-for-c-reactive-protein-based-on-ultrathin-films-of-carboxylated-cellulose-nanofibrils
#14
Yanxia Zhang, Orlando J Rojas
C-reactive protein (CRP) is an acute phase protein that has been widely used as a predictor of cardiovascular diseases. We report herein the synthesis of immunosensors based on carboxylated cellulose nanofibrils (CNF) for CRP detection, as demonstrated by quartz crystal microgravimetry (QCM). QCM sensors carrying ultrathin films of carboxylated CNF were prepared by using two protocols: (i) spin coating of CNF on the sensors followed by carboxylation via in situ oxidation with 2,2,6,6-tetramethylpiperidine 1-oxyl and (ii) carboxymethylation of CNF in aqueous dispersion followed by spin coating deposition on the sensors...
January 18, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28032021/detection-of-ligand-induced-conformational-changes-in-the-activation-loop-of-aurora-a-kinase-by-peldor-spectroscopy
#15
Selena G Burgess, Maria Grazia Concilio, Richard Bayliss, Alistair J Fielding
The structure of protein kinases has been extensively studied by protein crystallography. Conformational movement of the kinase activation loop is thought to be crucial for regulation of activity; however, in many cases the position of the activation loop in solution is unknown. Protein kinases are an important class of therapeutic target and kinase inhibitors are classified by their effect on the activation loop. Here, we report the use of pulsed electron double resonance (PELDOR) and site-directed spin labeling to monitor conformational changes through the insertion of MTSL [S-(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1 H-pyrrol-3-yl)methyl methanesulfonothioate] on the dynamic activation loop and a stable site on the outer surface of the enzyme...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28012884/erythrocytes-properties-in-varicose-veins-patients
#16
L Gwozdzinski, A Pieniazek, J Bernasinska, M Grabowski, E Kowalczyk, K Gwozdzinski
Varicose veins (VV) are enlarged veins of the subcutaneous tissue, usually caused by faulty or damaged venous valves leading to impaired blood flow. Blood stasis, excessive clotting disorder and alterations in the vein walls are symptoms of Virchow's triad which may affect the morphotic elements of blood, including erythrocytes. The aim of this study was to investigate alterations in the properties of the erythrocytes taken from varicose veins in comparison to those from antecubital vein of patients with chronic venous disease...
December 21, 2016: Microvascular Research
https://www.readbyqxmd.com/read/28006433/intracerebroventricular-tempol-administration-in-older-rats-reduces-oxidative-stress-in-the-hypothalamus-but-does-not-change-stat3-signalling-or-sirt1-ampk-pathway
#17
Hale Z Toklu, Philip J Scarpace, Yasemin Sakarya, Nataliya Kirichenko, Michael Matheny, Erin B Bruce, Christy S Carter, Drake Morgan, Nihal Tümer
Hypothalamic inflammation and increased oxidative stress are believed to be mechanisms that contribute to obesity. 4-Hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (tempol), a free radical scavenger, has been shown to reduce inflammation and oxidative stress. We hypothesized that brain infusion of tempol would reduce oxidative stress, and thus would reduce food intake and body weight and improve body composition in rats with age-related obesity and known elevated oxidative stress. Furthermore, we predicted an associated increase in markers of leptin signalling, including the silent mating type information regulator 2 homolog 1 (SIRT1)/5'AMP-activated protein kinase (AMPK) pathway and the signal transducer and activator of transcription 3 (STAT3) pathway...
January 2017: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/27997159/the-formation-time-of-ti-o-%C3%A2-and-ti-o-%C3%A2-ti-radicals-at-the-n-srtio3-aqueous-interface-during-photocatalytic-water-oxidation
#18
Xihan Chen, Stephanie N Choing, Daniel J Aschaffenburg, C D Pemmaraju, David Prendergast, Tanja Cuk
The initial step of photocatalytic water oxidation reaction at the metal oxide/aqueous interface involves intermediates formed by trapping photogenerated, valence band holes on different reactive sites of the oxide surface. In SrTiO3, these one-electron intermediates are radicals located in Ti-O(•) (oxyl) and Ti-O(•)-Ti (bridge) groups arranged perpendicular and parallel to the surface respectively, and form electronic states in the band gap of SrTiO3. Using an ultrafast sub band gap probe of 400 nm and white light, we excited transitions between these radical states and the conduction band...
December 20, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27995786/cellulose-nanofibers-prepared-using-the-tempo-laccase-o2-system
#19
Jie Jiang, Wenbo Ye, Liang Liu, Zhiguo Wang, Yimin Fan, Tsuguyuki Saito, Akira Isogai
The 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)/laccase/O2 system was used to prepare cellulose nanofibers from wood cellulose without requiring any chlorine-containing oxidant. Laccase was degraded by oxidized TEMPO (TEMPO(+)) formed by laccase-mediated oxidation with O2, which competed with the oxidation of wood cellulose. Thus, large amounts of laccase and TEMPO and a long reaction time were needed to introduce ∼0.6 mmol g(-1) of C6-carboxylate groups onto wood cellulose. The TEMPO/laccase/O2 system underwent one-way reaction from TEMPO to reduced TEMPO through TEMPO(+)...
December 20, 2016: Biomacromolecules
https://www.readbyqxmd.com/read/27980017/nitric-oxide-modulates-histone-acetylation-at-stress-genes-by-inhibition-of-histone-deacetylases
#20
Alexander Mengel, Alexandra Ageeva, Elisabeth Georgii, Jörg Bernhardt, Keqiang Wu, Jörg Durner, Christian Lindermayr
Histone acetylation, which is an important mechanism to regulate gene expression, is controlled by the opposing action of histone acetyltransferases (HATs) and histone deacetylases (HDACs). In animals, several HDACs are subjected to regulation by nitric oxide (NO), in plants however, it is unknown whether NO affects histone acetylation. We found that treatment with the physiological NO-donor S-nitroso-glutathione (GSNO) increased the abundance of several histone acetylation marks in Arabidopsis, which was strongly diminished in the presence of the NO scavenger 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO)...
December 15, 2016: Plant Physiology
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