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https://www.readbyqxmd.com/read/28229915/regulated-methionine-oxidation-by-monooxygenases
#1
REVIEW
Bruno Manta, Vadim N Gladyshev
Protein function can be regulated via post-translational modifications by numerous enzymatic and non-enzymatic mechanisms, including oxidation of cysteine and methionine residues. Redox-dependent regulatory mechanisms have been identified for nearly every cellular process, but the major paradigm has been that cellular components are oxidized (damaged) by reactive oxygen species (ROS) in a relatively unspecific way, and then reduced (repaired) by designated reductases. While this scheme may work with cysteine, it cannot be ascribed to other residues, such as methionine, whose reaction with ROS is too slow to be biologically relevant...
February 13, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28225599/cubic-sr2scgao5-perovskite-structural-stability-oxygen-defect-structure-and-ion-conductivity-explored-on-single-crystals
#2
Serena Corallini, Monica Ceretti, Alain Cousson, Clemens Ritter, Marco Longhin, Philippe Papet, Werner Paulus
Oxygen-deficient Sr2ScGaO5 single crystals with a cubic perovskite structure were grown by the floating-zone technique. The transparent crystals of this pure 3D oxygen electrolyte are metastable at ambient temperature, showing one-sixth of all oxygen positions vacant. While neutron single-crystal diffraction, followed by maximum entropy analysis, revealed a strong anharmonic displacements for the oxygen atoms, a predominant formation of ScO6 octahedra and GaO4 tetrahedra is indicated by Raman spectroscopic studies, resulting in a complex oxygen defect structure with short-range order...
February 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28222601/energy-related-small-molecule-activation-reactions-oxygen-reduction-and-hydrogen-and-oxygen-evolution-reactions-catalyzed-by-porphyrin-and-corrole-based-systems
#3
Wei Zhang, Wenzhen Lai, Rui Cao
Globally increasing energy demands and environmental concerns related to the use of fossil fuels have stimulated extensive research to identify new energy systems and economies that are sustainable, clean, low cost, and environmentally benign. Hydrogen generation from solar-driven water splitting is a promising strategy to store solar energy in chemical bonds. The subsequent combustion of hydrogen in fuel cells produces electric energy, and the only exhaust is water. These two reactions compose an ideal process to provide clean and sustainable energy...
February 22, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28221360/why-copper-is-preferred-over-iron-for-oxygen-activation-and-reduction-in-haem-copper-oxidases
#4
Ambika Bhagi-Damodaran, Matthew A Michael, Qianhong Zhu, Julian Reed, Braddock A Sandoval, Evan N Mirts, Saumen Chakraborty, Pierre Moënne-Loccoz, Yong Zhang, Yi Lu
Haem-copper oxidase (HCO) catalyses the natural reduction of oxygen to water using a haem-copper centre. Despite decades of research on HCOs, the role of non-haem metal and the reason for nature's choice of copper over other metals such as iron remains unclear. Here, we use a biosynthetic model of HCO in myoglobin that selectively binds different non-haem metals to demonstrate 30-fold and 11-fold enhancements in the oxidase activity of Cu- and Fe-bound HCO mimics, respectively, as compared with Zn-bound mimics...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28220171/towards-highly-active-pd-ceo2-for-alkene-hydrogenation-by-tuning-pd-dispersion-and-surface-properties-of-the-catalysts
#5
Sai Zhang, Jing Li, Zhaoming Xia, Chao Wu, Zhiyun Zhang, Yuanyuan Ma, Yongquan Qu
Extensive applications of noble metals as heterogeneous catalysts are limited by their global reserve scarcity and exorbitant price. Identifying the intrinsic active nature of a catalyst benefits the designing of catalysts with trace amounts of noble metals; these catalysts display better or comparable overall catalytic efficiency than their heavily loaded counterparts. Herein, systematic studies on Pd dispersion and surface properties of a series of Pd/CeO2 catalysts for styrene hydrogenation showed that high Pd dispersion and surface abundant defects of the catalysts are essential to realize superior activity...
February 21, 2017: Nanoscale
https://www.readbyqxmd.com/read/28219939/peroxiredoxin-1-prx1-is-a-dual-function-enzyme-by-possessing-cys-independent-catalase-like-activity
#6
Cen-Cen Sun, Wei-Ren Dong, Tong Shao, Jiang-Yuan Li, Jing Zhao, Li Nie, Li-Xin Xiang, Guan Zhu, Jian-Zhong Shao
Peroxiredoxin (Prx) was previously known as a Cys-dependent thioredoxin. However, we unexpected observed that Prx1 from the green spotted puffer fish Tetraodon nigroviridis (TnPrx1) was able to reduce H2O2 in a manner independent on the Cys peroxidation and reductants. This study aimed to validate the novel function for Prx1, delineate the biochemical features and explore its antioxidant role in cells. We have confirmed that Prx1 from the puffer fish and humans truly possesses a catalase-like activity that is independent of Cys residues and reductants, but dependent on iron...
February 20, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28218849/theoretical-study-of-the-heterolytic-%C3%AF-bond-cleavage-on-the-ge%C3%A2-o-bond-of-germanone-an-insight-into-the-driving-force-from-both-electronic-and-dynamical-aspects
#7
Toshiaki Matsubara, Tomoyoshi Ito
The mechanism of the σ bond cleavage of H2O, NH3, Me2C═O, H2, CH4, BH3, and SiH4 on the Ge═O bond of germanone is examined by means of both quantum mechanical (QM) and molecular dynamics (MD) methods. The QM calculations show that the σ bonds of all the substrates are heterolytically broken on the very largely polarized Ge═O bond. Before the σ bond cleavage, the substrate at first approach the Ge═O germanium in the cases of H2O, Me2C═O, and NH3, and in contrast, the Ge═O oxygen in the cases of H2, CH4, BH3, and SiH4...
February 20, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28218800/hydrogen-atom-transfer-hat-initiated-by-intramolecular-ligand-metal-electron-transfer
#8
Hendrik Herrmann, Elisabeth Kaifer, Hans-Jörg Himmel
Hydrogen-atom transfer (HAT) is of key importance for several catalytic and biological processes, and provides an elegant access to C-H activation. In synthetic chemistry, a photoactivated metal complex is often employed to abstract an oxygen- or nitrogen-bound hydrogen, and the as generated oxygen- or nitrogen-centered radical is the hydrogen atom acceptor for HAT. Herein we report the first examples for HAT processes initiated by one-electron oxidation of urea azines. A further novelty is that the HAT-initiating oxidation can be realized by intramolecular ligand-metal electron transfer in copper(II)-urea azine complexes...
February 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28217747/insights-into-photosystem-ii-from-isomorphous-difference-fourier-maps-of-femtosecond-x-ray-diffraction-data-and-quantum-mechanics-molecular-mechanics-structural-models
#9
REVIEW
Jimin Wang, Mikhail Askerka, Gary W Brudvig, Victor S Batista
Understanding structure-function relations in photosystem II (PSII) is important for the development of biomimetic photocatalytic systems. X-ray crystallography, computational modeling, and spectroscopy have played central roles in elucidating the structure and function of PSII. Recent breakthroughs in femtosecond X-ray crystallography offer the possibility of collecting diffraction data from the X-ray free electron laser (XFEL) before radiation damage of the sample, thereby overcoming the main challenge of conventional X-ray diffraction methods...
February 10, 2017: ACS Energy Lett
https://www.readbyqxmd.com/read/28215595/gas-exchange-kinetics-following-concentric-eccentric-isokinetic-arm-and-leg-exercise
#10
U Drescher, S Mookerjee, A Steegmanns, A Knicker, U Hoffmann
PURPOSE: To evaluate the effects of exercise velocity (60, 150, 240 deg·s(-1)) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO2) following high-intensity concentric-eccentric isokinetic exercise. METHODS: Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t1/2) for oxygen uptake (V'O2pulm), carbon dioxide output (V'CO2pulm), and ventilation (V'E)...
February 16, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28215087/microwave-initiated-facile-formation-of-ni3se4-nanoassemblies-for-enhanced-and-stable-water-splitting-in-neutral-and-alkaline-media
#11
Sengeni Anantharaj, Jeevarathinam Kennedy, Subrata Kundu
Molecular hydrogen (H2) generation through water splitting with minimum energy loss has become practically possible due to the recent evolution of high performance electrocatalysts. In this study, we had fabricated, evaluated and presented such a high performance catalyst which is the Ni3Se4 nanoassemblies that can efficiently catalyze water splitting in neutral and alkaline media. A hierarchical nanoassemblies of Ni3Se4 was fabricated by functionalizing the surface cleaned Ni foam using NaHSe solution as Se source with the assistance of microwave irradiation (300 W) for 3 min followed by 5 h of aging at room temperature (RT)...
February 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28215084/effect-of-l-cysteine-and-transition-metal-ions-on-dimethyl-sulfide-oxidation
#12
Matthias Baldus, Rüdiger Klie, Xi De, Frank-Juergen Methner
During malt kilning, significant amounts of dimethyl sulfide (DMS) oxidize leading to the formation of dimethyl sulfoxide (DMSO), a precursor of DMS during fermentation. Yet, knowledge regarding reaction mechanisms of DMSO formation during malt production is limited. The role of thiols in sulfide oxidation is unclear as they possess sulfoxide reducing ability as well as pro- and antioxidative properties. This study investigated the effects of the thiol L-cysteine (Cys), molecular oxygen, transition metal ions and EDTA on DMS oxidation in aqueous model solutions...
February 18, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28214421/effects-of-molecular-size-fraction-of-dom-on-photodegradation-of-aqueous-methylmercury
#13
Moon-Kyung Kim, A-Young Won, Kyung-Duk Zoh
This study investigated the photodegradation kinetics of MeHg in the presence of various size fractions of dissolved organic matter (DOM) with MW < 3.5 kDa, 3.5 < MW < 10 kDa, and MW > 10 kDa. The DOM fraction with MW < 3.5 kDa was most effective in MeHg photodegradation. Increasing UV intensity resulted in the increase of photodegradation rate of the MeHg in all size of DOM fractions. Higher rates of MeHg degradation was observed at higher pH. For the portion of MW < 3.5 kDa, the photodegradation rate of MeHg increased with increasing DOM concentration, indicating that radicals such as singlet oxygen ((1)O2) radicals can be effectively produced by DOM...
February 6, 2017: Chemosphere
https://www.readbyqxmd.com/read/28213710/biohydrogen-production-from-sugarcane-bagasse-hydrolysate-effects-of-ph-s-x-fe-2-and-magnetite-nanoparticles
#14
Karen Reddy, Mahmoud Nasr, Sheena Kumari, Santhosh Kumar, Sanjay Kumar Gupta, Abimbola Motunrayo Enitan, Faizal Bux
Batch dark fermentation experiments were conducted to investigate the effects of initial pH, substrate-to-biomass (S/X) ratio, and concentrations of Fe(2+) and magnetite nanoparticles on biohydrogen production from sugarcane bagasse (SCB) hydrolysate. By applying the response surface methodology, the optimum condition of steam-acid hydrolysis was 0.64% (v/v) H2SO4 for 55.7 min, which obtained a sugar yield of 274 mg g(-1). The maximum hydrogen yield (HY) of 0.874 mol (mol glucose(-1)) was detected at the optimum pH of 5...
February 18, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28213335/transformation-products-of-clindamycin-in-moving-bed-biofilm-reactor-mbbr
#15
Gordon T H Ooi, Monica Escola Casas, Henrik R Andersen, Kai Bester
Clindamycin is widely prescribed for its ability to treat a number of common bacterial infections. Thus, clindamycin enters wastewater via human excretion or disposal of unused medication and widespread detection of pharmaceuticals in rivers proves the insufficiency of conventional wastewater treatment plants in removing clindamycin. Recently, it has been discovered that attached biofilm reactors, e.g., moving bed biofilm reactors (MBBRs) obtain a higher removal of pharmaceuticals than conventional sludge wastewater treatment plants...
February 2, 2017: Water Research
https://www.readbyqxmd.com/read/28211331/sulfamethoxazole-and-cod-increase-abundance-of-sulfonamide-resistance-genes-and-change-bacterial-community-structures-within-sequencing-batch-reactors
#16
Xueping Guo, Weihai Pang, Chunling Dou, Daqiang Yin
The abundant microbial community in biological treatment processes in wastewater treatment plants (WWTPs) may potentially enhance the horizontal gene transfer of antibiotic resistance genes with the presence of antibiotics. A lab-scale sequencing batch reactor was designed to investigate response of sulfonamide resistance genes (sulI, sulII) and bacterial communities to various concentrations of sulfamethoxazole (SMX) and chemical oxygen demand (COD) of wastewater. The SMX concentrations (0.001 mg/L, 0.1 mg/L and 10 mg/L) decreased with treatment time and higher SMX level was more difficult to remove...
February 1, 2017: Chemosphere
https://www.readbyqxmd.com/read/28211275/suppression-of-hydrogen-evolution-by-oxygen-reduction-in-nanoporous-electrocatalysts
#17
Ellen Benn, Bernard Gaskey, Jonah D Erlebacher
Electroreduction of small molecules in aqueous solution often competes with the hydrogen evolution reaction (HER), especially if the reaction is driven even moderately hard using a large overpotential. Here, the oxygen reduction reaction (ORR) was studied under proton diffusion-limited conditions in slightly acidic electrolytes - a model system to study the relative transport kinetics of protons and reactants to an electrocatalyst and the relationship between transport and catalytic performance. Using dealloyed nanoporous nickel-platinum (np-NiPt) electrodes, we find the hydrogen evolution reaction can be completely suppressed even at high overpotentials (-400 mV vs...
February 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28209841/salicylic-acid-dependent-plant-stress-signalling-via-mitochondrial-succinate-dehydrogenase
#18
Katharina Belt, Shaobai Huang, Louise F Thatcher, Hayley Casarotto, Karam Singh, Olivier Van Aken, A Harvey Millar
Mitochondria are known for their role in ATP production and generation of reactive oxygen species (ROS), but little is known about the mechanism of their early involvement in plant stress signalling. The role of mitochondrial succinate dehydrogenase (SDH) in salicylic acid (SA) signalling was analysed using two mutants; disrupted in stress response 1 (dsr1) which is a point mutation in SDH1 identified in a loss of SA signalling screen, and a knockdown mutant (sdhaf2) for SDH assembly factor 2 that is required for FAD insertion into SDH1...
February 16, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28207229/efficient-and-durable-bifunctional-oxygen-catalysts-based-on-nifeo-mnox-core-shell-structures-for-rechargeable-zn-air-batteries
#19
Yi Cheng, Shuo Dou, Jean-Pierre Veder, Shuangyin Wang, Martin Saunders, San Ping Jiang
Rechargeable Zn-air battery is limited by the sluggish kinetics and poor durability of the oxygen catalysts. In this paper, a new bifunctional oxygen catalyst has been developed through embedding the ultrafine NiFeO nanoparticles (NPs) in a porous amorphous MnOx layer, in which the NiFeO-core contributes to the high activity for oxygen evolution reaction (OER) and the amorphous MnOx-shell functions as active phase for oxygen evolution reaction (OER), promoted by the synergistic effect between the NiFeO core and MnOx shell...
February 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28202306/nitrite-oxidation-kinetics-of-two-nitrospira-strains-the-quest-for-competition-and-ecological-niche-differentiation
#20
Norisuke Ushiki, Masaru Jinno, Hirotsugu Fujitani, Toshikazu Suenaga, Akihiko Terada, Satoshi Tsuneda
Nitrite oxidation is an aerobic process of the nitrogen cycle in natural ecosystems, and is performed by nitrite-oxidizing bacteria (NOB). Also, nitrite oxidation is a rate-limiting step of nitrogen removal in wastewater treatment plants (WWTPs). Although Nitrospira is known as dominant NOB in WWTPs, information on their physiological properties and kinetic parameters is limited. Here, we report the kinetic parameters and inhibition of nitrite oxidation by free ammonia in pure cultures of Nitrospira sp. strain ND1 and Nitrospira japonica strain NJ1, which were previously isolated from activated sludge in a WWTP...
February 12, 2017: Journal of Bioscience and Bioengineering
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