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w hydroxylation

Gunnar R Stratton, Fei Dai, Christopher L Bellona, Thomas M Holsen, Eric Reyvell Velazquez Dickenson, Selma Mededovic Thagard
A process based on electrical discharge plasma was tested for the transformation of perfluorooctanoic acid (PFOA). The plasma-based process was adapted for two cases, high removal rate and high removal efficiency. During a 30 minute treatment, the PFOA concentration in 1.4 L aqueous solutions was reduced by 90% with the high rate process (76.5 W input power) and 25% with the high efficiency process (4.1 W input power). Both achieved remarkably high PFOA removal and defluorination efficiencies compared to leading alternative technologies...
January 12, 2017: Environmental Science & Technology
Eli A Sutter, Peter W Sutter
Galvanic replacement reactions are important as they transform nanoparticle templates into complex porous and hollow metal or alloy nanostructures with interesting properties for a variety of applications. Real-time liquid cell electron microscopy (LCEM) observations of the transformation of solid nanoparticles into hollow shell and cage bimetallic nanostructures are challenging because the high-energy electron beam strongly affects the galvanic process via species such as aqueous electrons and hydroxyl radicals generated through the radiolysis of water in the liquid cell...
January 5, 2017: Nanoscale
Robert F Hansen, Tom R Lewis, Lee Graham, Lisa K Whalley, Paul W Seakins, Dwayne E Heard, Mark A Blitz
In environments with high concentrations of biogenic volatile organic compounds and low concentrations of nitrogen oxides (NOx = NO + NO2), significant discrepancies have been found between measured and modeled concentrations of hydroxyl radical (OH). The photolysis of peroxy radicals from isoprene (HO-Iso-O2) in the near ultraviolet represents a potential source of OH in these environments, yet has not been considered in atmospheric models. This paper presents measurements of the absorption cross-sections for OH formation (σRO2,OH) from the photolysis of HO-Iso-O2 at wavelengths from 310-362...
January 5, 2017: Physical Chemistry Chemical Physics: PCCP
Sarah Matthews, James D Belcher, Kang Lan Tee, Hazel M Girvan, Kirsty J McLean, Stephen Ej Rigby, Colin W Levy, David Leys, David A Parker, Richard T Blankley, Andrew W Munro
The Jeotgalicoccus sp. peroxygenase cytochrome P450 OleTJE (CYP152L1) is a hydrogen peroxide-driven oxidase that catalyzes oxidative decarboxylation of fatty acids, producing terminal alkenes with applications as fine chemicals and biofuels. Understanding mechanisms that favor decarboxylation over fatty acid hydroxylation in OleTJE could enable protein engineering to improve catalysis or to introduce decarboxylation activity into P450s with different substrate preferences. In this manuscript, we have focused on OleTJE active site residues Phe79, His85 and Arg245 to interrogate their roles in substrate binding and catalytic activity...
January 4, 2017: Journal of Biological Chemistry
Y Seo
PURPOSE: The poor reliability and repeatability of the manufacturer-reported SAR values on clinical MRI systems have been acknowledged. The purpose of this study is to not only measure SAR values, but also RF-induced temperature elevation at 1.5 and 3T MRI systems. METHODS: SAR measurement experiment was performed at 1.5 and 3T. Three MRI RF sequences (T1w TSE, T1w inversion recovery, and T2w TSE) with imaging parameters were selected. A hydroxyl-ethylcelluose (HEC) gelled saline phantom mimicking human body tissue was made...
June 2016: Medical Physics
Z Ouyang, G Strack, E Sajo, W Ngwa
PURPOSE: Hydroxyl radicals can be produced within tissue by radiation therapy, and they are largely responsible for DNA damage and cell killing. Coumarin-3-carboxylic acid (3-CCA) and crystal violet are reported to react with hydroxyl radicals and can be used for fluorescence and absorbance measurements, respectively. This study assesses the ability of hydroxyl measurement for both 3-CCA and crystal violet in radiolized water systems in order to provide dosimetric information in radiation chemistry and radiation biology experiments...
June 2016: Medical Physics
Ammar Abdulmughni, Ilona K Jóźwik, Natalia Putkaradze, Elisa Brill, Josef Zapp, Andy-Mark W H Thunnissen, Frank Hannemann, Rita Bernhardt
In this study the ability of CYP109E1 from Bacillus megaterium to metabolize vitamin D3 (VD3) was investigated. In an in vitro system using bovine adrenodoxin reductase (AdR) and adrenodoxin (Adx4-108), VD3 was converted by CYP109E1 into several products. Furthermore, a whole-cell system in B. megaterium MS941 was established. The new system showed a conversion of 95% after 24h. By NMR analysis it was found that CYP109E1 catalyzes hydroxylation of VD3 at carbons C-24 and C-25, resulting in the formation of 24(S)-hydroxyvitamin D3 (24S(OH)VD3), 25-hydroxyvitamin D3 (25(OH)VD3) and 24S,25-dihydroxyvitamin D3 (24S,25(OH)2VD3)...
December 30, 2016: Journal of Biotechnology
B L Pan, H T Zhang, H J Zhang, W T Chen, J Yang
Objective: To investigate the relationship between urinary polycyclic aromatic hydrocarbon metabolite and cell cycle of lymphocyte in coke oven workers. Methods: 437 coke oven workers and 163 work-ers in water treatment department were recruited in this study. Flow cytometry was used to detect the cell cycle of lymphocyte. For the measurement of urinary metabolites, urine samples were treated with β-glucuronidase and analyzed using HPLC with a fluorescence detector. Results: The concentrations of urinary 2-naphthol, 2-hydroxyfluorene, 9-phenanthrol and 1-hydroxypyrene l in coke oven workers were significantly higher than those in control group (P<0...
November 20, 2016: Chinese Journal of Industrial Hygiene and Occupational Diseases
Arnaud W G Tamba Sompila, Sylvie Héron, Dorra Hmida, Alain Tchapla
The distribution of fatty acid species at the sn-1/3 position or the sn-2 position of triacylglycerols (TAGs) in natural fats and oils affects their physical and nutritional properties. In fats and oils, determining the presence of one or two regioisomers and the identification of structure, where they do have one, as well as their separation, became a problem of fundamental importance to solve. A variety of instrumental technics has been proposed, such as MS, chromatography-MS or pure chromatography. A number of studies deal with the optimization of the separation, but very often, they are expensive in time...
January 15, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Cezary Skobowiat, Allen S W Oak, Tae-Kang Kim, Chuan He Yang, Lawrence M Pfeffer, Robert C Tuckey, Andrzej T Slominski
A novel pathway of vitamin D3 (D3) metabolism, initiated by C20-hydroxylation of D3 by CYP11A1, has been confirmed to operate in vivo. Its major product, 20(OH)D3, exhibits antiproliferative activity in vitro comparable to that of 1,25(OH)2D3, but is noncalcemic in mice and rats. To further characterize the antimelanoma activity of 20(OH)D3, we tested its effect on colony formation of human melanoma cells in monolayer culture and anchorage-independent growth in soft agar. The migratory capabilities of the cells and cell-cell and cell-extracellular matrix interactions were also evaluated using transwell cell migration and spheroid toxicity assays...
December 26, 2016: Oncotarget
Yunpan Ying, Dahuan Liu, Weixin Zhang, Jing Ma, Hongliang Huang, Qingyuan Yang, Chongli Zhong
Graphene oxide (GO) membranes assembled by single-atom thick GO nanosheets have displayed huge potential application both in gas and liquid separation process due to its facile and large-scale preparation resulting from various functional groups, such as hydroxyl, carboxyl and epoxide groups. Taking advantage of these characters, GO membranes intercalated by super-hydrophilic metal-organic frameworks (MOFs) as strengthening separation fillers were prepared on modified polyacrylonitrile (PAN) support by a novel pressure-assisted self-assembly (PASA) filtration technique instead of traditional vacuum filtration method for the first time...
December 21, 2016: ACS Applied Materials & Interfaces
Jessica K Holien, Michael W Parker, Alan J Conley, C Jo Corbin, Raymond J Rodgers, Lisandra L Martin
Cytochrome P450 17α-hydroxylase, 17,20-lyase (P450c17) is a key enzyme in the synthesis of cortisol in the zona fascicula of the adrenal cortex, and the synthesis of androgen precursors in the adrenal zona reticularis and the gonads. Each of these reactions require electrons transferred by the electron donor cytochrome P450 oxidoreductase. The 17-hydroxylation of its substrate occurs in all cells where P450c17 is expressed. Remarkably, a second, subsequent reaction, namely the 17,20-lyase activity, only occurs in the zona reticularis and gonads...
December 20, 2016: Current Protein & Peptide Science
R T De Silva, M M M G P G Mantilaka, S P Ratnayake, G A J Amaratunga, K M Nalin de Silva
Chitosan nanocomposite thin films were fabricated by incorporating MgO nanoparticles to significantly improve its physical properties for potential packaging applications. A novel in-situ method was developed to synthesise spherical shaped MgO nanoparticles by heat-treating magnesium carbonate/poly(methyl methacrylate) (PMMA) composite precursor. Optimum mechanical properties of chitosan composites were yielded at 5 (w/w%) of MgO concentration, where tensile stress and elastic modulus significantly improved by 86% and 38%, respectively, compared to those of pure chitosan films...
February 10, 2017: Carbohydrate Polymers
Elisabet Quintana, M Blanca Roncero, Teresa Vidal, Cristina Valls
In this work, laccase-TEMPO (Lac-T) treatments were applied to bleached commercial dissolving pulp in order to introduce carbonyl and carboxyl groups, which were found to improve dry and wet strength-related properties. Also the solubility behavior towards xanthate reactions was assessed. The effect of a refining step (R) before the oxidative treatment, the absence or presence of oxygen pressure, TEMPO dose (2 or 8% oven dried pulp) and reaction time (8 or 20h) were thoroughly examined. Treatments conducted in the presence of oxygen pressure exhibited greater amount of functional groups...
February 10, 2017: Carbohydrate Polymers
Yi Wang, Peter W Villalta, Lijuan Peng, Karen H Dingley, Michael A Malfatti, Kenneth W Turteltaub, Robert J Turesky
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a carcinogenic heterocyclic aromatic amine formed during the high temperature cooking of meats. The cytochrome P450-mediated N-hydroxylation of the exocyclic amine group of PhIP produces 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (HONH-PhIP), an electrophilic metabolite which forms adducts with DNA and proteins. Previous studies conducted by our laboratory showed that the reaction of N-oxidized-PhIP metabolites with human albumin in vitro primarily occurs at the Cys34 residue, to produce an acid-labile linked sulfinamide adduct...
December 16, 2016: Chemical Research in Toxicology
Shuangliang Zhao, Bicai Zhan, Yaofeng Hu, Zhaoyu Fan, Marc Pera-Titus, Honglai Liu
Pickering emulsions combining surface-active and catalytic properties offer a promising platform for conducting interfacial reactions between immiscible reagents. Despite the significant progress in the design of Pickering interfacial catalysts for a broad panel of reactions, the dynamics of Pickering emulsions under reaction conditions is still poorly understood. Herein, using benzene hydroxylation with aqueous H2O2 as a model system, we explored the dynamics of benzene/water Pickering emulsions during reaction by dissipative particle dynamics...
December 13, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
By Ji-Fa Zhang, Lian-Hai Shan, Feng Gao, Shuai Huang, Xian-Li Zhou
Five new diterpenoid alkaloids tianshanitine A-E (1-5), along with ten known compounds (6-15), were isolated from the ethanolic extracts of the whole plant of Delphinium tianshanicum W. T. Wang. Their structures were determined based on extensive spectroscopic analyses, including 1D, 2D NMR, HRESIMS, and the structure of tianshanitine C (3) was confirmed by X-ray diffraction analysis. Tianshanitine A (1) is the first example of natural diterpenoid alkaloid containing a benzoyl group at C-1 position. Tianshanitine B (2) is a rare natural diterpenoid alkaloid including a hydroxyl group at C-16 position...
December 9, 2016: Chemistry & Biodiversity
Lin Li, Sheng Shu, Qing Xu, Ya-Hong An, Jin Sun, Shi-Rong Guo
Nitric oxide (NO) and hydrogen peroxide (H2 O2 ), two important signalling molecules, are stimulated in plants by abiotic stresses. In this study, we investigated the role of NO and its interplay with H2 O2 in the response of self-grafted and salt-tolerant pumpkin-grafted (Cucurbita maxima × C. moschata) cucumber seedlings to 80 mM Ca(NO3 )2 stress. Endogenous NO and H2 O2 production in self-grafted seedlings increased in a time-dependent manner, reaching maximum levels after 24 h of Ca(NO3 )2 stress. In contrast, a transient increase in NO production, accompanied by H2 O2 accumulation, was observed at 2 h in rootstock-grafted plants...
December 9, 2016: Physiologia Plantarum
Nicholas J Porter, Nicolas H Christianson, Christophe Decroos, David W Christianson
Histone deacetylase 8 (HDAC8) catalyzes the hydrolysis of acetyl-l-lysine to yield products l-lysine and acetate through a mechanism in which a nucleophilic water molecule is activated by a histidine general base and a catalytic metal ion (Zn(2+) or Fe(2+)). Acetyl-l-lysine also requires activation by metal coordination and a hydrogen bond with catalytic tyrosine Y306, which also functions in transition state stabilization. Interestingly, Y306 is located in the conserved glycine-rich loop G(302)GGGY. The potential flexibility afforded by the tetraglycine segment may facilitate induced-fit conformational changes in Y306 between "in" and "out" positions, as observed in related deacetylases...
December 6, 2016: Biochemistry
Zhenqiu Li, Ruiping Gao, Qinggang Hao, Huifang Zhao, Longbin Cheng, Fang He, Li Liu, Xiuhua Liu, Wayne K W Chou, Huajie Zhu, David E Cane
The T296V mutant of amorpha-4,11-diene synthase catalyzes the abortive conversion of the natural substrate (E,E)-farnesyl diphosphate mainly into the acyclic product (E)-β-farnesene (88%) instead of the natural bicyclic sesquiterpene amorphadiene (7%). Incubation of the T296V mutant with (3R,6E)-nerolidyl diphosphate resulted in cyclization to amorphadiene. Analysis of additional mutants of amino acid residue 296 and in vitro assays with the intermediate analogue (2Z,6E)-farnesyl diphosphate as well as (3S,6E)-nerolidyl diphosphate demonstrated that the T296V mutant can no longer catalyze the allylic rearrangement of farnesyl diphosphate to the normal intermediate (3R,6E)-nerolidyl diphosphate, while retaining the ability to cyclize (3R,6E)-nerolidyl diphosphate to amorphadiene...
December 6, 2016: Biochemistry
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