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https://www.readbyqxmd.com/read/28637348/hydrogen-peroxide-sensing-based-on-inner-surfaces-modification-of-solid-state-nanopore
#1
Libo Zhu, Dejian Gu, Quanjun Liu
There are many techniques for the detection of molecules. But detection of molecules through solid-state nanopore in a solution is one of the promising, high-throughput, and low-cost technology used these days. In the present investigation, a solid-state nanopore platform was fabricated for the detection of hydrogen peroxide (H2O2), which is not only a label free product but also a significant participant in the redox reaction. We have successfully fabricated silicon nitride (Si3N4) nanopores with diameters of ~50 nm by using a focused Ga ion beam, the inner surface of the nanopore has been modified with horseradish peroxidase (HRP) by employing carbodiimide coupling chemistry...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28637173/crystallographic-analyses-illustrate-significant-plasticity-and-efficient-recoding-of-meganuclease-target-specificity
#2
Rachel Werther, Jazmine P Hallinan, Abigail R Lambert, Kyle Havens, Mark Pogson, Jordan Jarjour, Roberto Galizi, Nikolai Windbichler, Andrea Crisanti, Tony Nolan, Barry L Stoddard
The retargeting of protein-DNA specificity, outside of extremely modular DNA binding proteins such as TAL effectors, has generally proved to be quite challenging. Here, we describe structural analyses of five different extensively retargeted variants of a single homing endonuclease, that have been shown to function efficiently in ex vivo and in vivo applications. The redesigned proteins harbor mutations at up to 53 residues (18%) of their amino acid sequence, primarily distributed across the DNA binding surface, making them among the most significantly reengineered ligand-binding proteins to date...
June 20, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28637168/sulfur-balance-of-sulfur-dioxide-ethanol-water-fractionation-of-sugarcane-straw
#3
Xiang You, Adriaan van Heiningen, Herbert Sixta, Mikhail Iakovlev
The sulfur balance of SO2-ethanol-water (AVAP®) fractionation of sugarcane (SC) straw was investigated. Hydrogen sulfite and sulfite anions are nearly absent in the liquors, despite cations present in straw, whose effect is thus limited to neutralization of lignosulfonic acids decreasing the acidity. Higher degree of sulfonation was observed for dissolved straw lignin compared to wood lignin (0.8-0.9 vs. 0.25 S/C9). Sulfur dioxide amounts of 0.9-1.2, 4.1-4.3 and 44-49g per o.d.kg straw were bound to pulp, precipitated lignin and lignosulfonic acid, respectively, while the rest of SO2 was recovered by distillation from the spent fractionation suspensions...
June 10, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28637162/response-of-antimicrobial-nitrofurazone-degrading-biocathode-communities-to-different-cathode-potentials
#4
Deyong Kong, Hui Yun, Dan Cui, Mengyuan Qi, Chunyan Shao, Dichen Cui, Nanqi Ren, Bin Liang, Aijie Wang
Bioelectrodegradation of various organic pollutants has been extensively studied. However, whether different cathode potentials could alter the antimicrobial-degrading biocathode community structure and composition remain poorly understood. Here, the microbial community structure and composition of the nitrofurans nitrofurazone (NFZ) degrading biocathode in response to different cathode potentials (-0.45±0.01, -0.65±0.01 and -0.86±0.05V vs standard hydrogen electrode, with applied cell voltages of 0.2, 0...
June 13, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28636951/structure-of-cc-chemokine-receptor-5-with-a-potent-chemokine-antagonist-reveals-mechanisms-of-chemokine-recognition-and-molecular-mimicry-by-hiv
#5
Yi Zheng, Gye Won Han, Ruben Abagyan, Beili Wu, Raymond C Stevens, Vadim Cherezov, Irina Kufareva, Tracy M Handel
CCR5 is the primary chemokine receptor utilized by HIV to infect leukocytes, whereas CCR5 ligands inhibit infection by blocking CCR5 engagement with HIV gp120. To guide the design of improved therapeutics, we solved the structure of CCR5 in complex with chemokine antagonist [5P7]CCL5. Several structural features appeared to contribute to the anti-HIV potency of [5P7]CCL5, including the distinct chemokine orientation relative to the receptor, the near-complete occupancy of the receptor binding pocket, the dense network of intermolecular hydrogen bonds, and the similarity of binding determinants with the FDA-approved HIV inhibitor Maraviroc...
June 20, 2017: Immunity
https://www.readbyqxmd.com/read/28636914/peptide-protein-binding-investigated-by-far-ir-spectroscopy-and-molecular-dynamics-simulations
#6
Yoann Cote, Yves Nominé, Juan Ramirez, Petra Hellwig, Roland H Stote
Molecular dynamics (MD) simulations and far-infrared (far-IR) spectroscopy were combined to study peptide binding by the second PDZ domain (PDZ1) of MAGI1, which has been identified as an important target for the Human Papilloma Virus. PDZ1 recognizes and binds to the C-terminal end of the E6 protein from high-risk Human Papilloma Virus. The far-IR spectra of two forms of the protein, an unbound APO form and a HOLO form (where the PDZ1 is bound to an 11-residue peptide derived from the C terminus of HPV16 E6), were obtained...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636908/schiff-base-proton-acceptor-assists-photoisomerization-of-retinal-chromophores-in-bacteriorhodopsin
#7
Chih-Chang Hung, Xiao-Ru Chen, Ying-Kuan Ko, Takayoshi Kobayashi, Chii-Shen Yang, Atsushi Yabushita
In this study, we investigated the ultrafast dynamics of bacteriorhodopsins (BRs) from Haloquadratum walsbyi (HwBR) and Haloarcula marismortui (HmBRI and HmBRII). First, the ultrafast dynamics were studied for three HwBR samples: wild-type, D93N mutation, and D104N mutation. The residues of the D93 and D104 mutants correspond to the control by the Schiff base proton acceptor and donor of the proton translocation subchannels. Measurements indicated that the negative charge from the Schiff base proton acceptor residue D93 interacts with the ultrafast and substantial change of the electrostatic potential associated with chromophore isomerization...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636684/balanced-work-function-as-a-driver-for-facile-hydrogen-evolution-reaction-comprehension-and-experimental-assessment-of-interfacial-catalytic-descriptor
#8
Aleksandar R Zeradjanin, Ashokanand Vimalanandan, George Polymeros, Angel A Topalov, Karl J J Mayrhofer, Michael Rohwerder
A major step in the development of (electro)catalysis would be the possibility to estimate accurately the energetics of adsorption processes related to reaction intermediates. Computational chemistry (e.g. using DFT) developed significantly in that direction and allowed the fast prediction of (electro)catalytic activity trends and improved the general understanding of adsorption at electrochemical interfaces. However, building a reliable and comprehensive picture of electrocatalytic reactions undoubtedly requires experimental assessment of adsorption energies...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28636605/catalytic-allylic-oxidation-of-internal-alkenes-to-a-multifunctional-chiral-building-block
#9
Liela Bayeh, Phong Q Le, Uttam K Tambar
The stereoselective oxidation of hydrocarbons is one of the most notable advances in synthetic chemistry over the past fifty years. Inspired by nature, enantioselective dihydroxylations, epoxidations and other oxidations of unsaturated hydrocarbons have been developed. More recently, the catalytic enantioselective allylic carbon-hydrogen oxidation of alkenes has streamlined the production of pharmaceuticals, natural products, fine chemicals and other functional materials. Allylic functionalization provides a direct path to chiral building blocks with a newly formed stereocentre from petrochemical feedstocks while preserving the olefin functionality as a handle for further chemical elaboration...
June 21, 2017: Nature
https://www.readbyqxmd.com/read/28636596/selective-sp-3-c-h-alkylation-via-polarity-match-based-cross-coupling
#10
Chip Le, Yufan Liang, Ryan W Evans, Ximing Li, David W C MacMillan
The functionalization of carbon-hydrogen (C-H) bonds is one of the most attractive strategies for molecular construction in organic chemistry. The hydrogen atom is considered to be an ideal coupling handle, owing to its relative abundance in organic molecules and its availability for functionalization at almost any stage in a synthetic sequence. Although many C-H functionalization reactions involve C(sp(3))-C(sp(2)) coupling, there is a growing demand for C-H alkylation reactions, wherein sp(3) C-H bonds are replaced with sp(3) C-alkyl groups...
June 21, 2017: Nature
https://www.readbyqxmd.com/read/28636451/assessing-hydrogen-peroxide-vapor-exposure-from-hospital-sterilizers
#11
Robert Cornelia, P Richard Warburton
This study examined the hydrogen peroxide concentrations measured near four models of hydrogen peroxide sterilizers, from two manufacturers, monitored in seven hospitals across the US and Canada over several years. The results showed that the majority of sterilizers do not emit hazardous levels of hydrogen peroxide and none of them exceeded the OSHA PEL of 1 ppm (8 hour time weighted average (TWA)), however several of the sterilizers exceeded 3 ppm, the short term exposure limit in a couple of states, Washington and Hawaii...
June 21, 2017: Journal of Occupational and Environmental Hygiene
https://www.readbyqxmd.com/read/28636401/one-step-solvothermal-synthesis-of-petalous-carbon-coated-cu-doped-cds-nanocomposites-with-enhanced-photocatalytic-hydrogen-production
#12
Bin He, Ren Liu, Jiabin Ren, Caijian Tang, Yijun Zhong, Yong Hu
Metal ion doping and nanocoating to CdS photocatalyst have been proved to be effective strategies to inhibit photocorrosion and improve photocatalytic performance. In this study, carbon-coated Cu+-doped CdS nanocomposites (C-Cu-CdS) with a stable petalous structure and highly uniform size distribution were successfully synthesized via a facile one-step solvothermal method. Both Cu+ doping and carbon coating to the CdS photocatalyst are realized in this one-step strategy. Benefiting from the unique core-shell structure and metal ion doping, the as-prepared C-Cu-CdS catalyst exhibits significantly enhanced photostability and visible-light-driven photocatalytic efficiency...
June 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28636375/one-pot-synthesis-of-functionalized-carbazoles-via-a-can-catalyzed-multicomponent-process-comprising-a-c-h-activation-step
#13
Juan Francisco González, Damiano Rocchi, Tomas Tejero, Pedro Merino, J Carlos Menéndez
The microwave-promoted three-component reaction between o-nitrochalcones, primary amines and β-dicarbonyl compounds in the presence of Ce(IV) ammonium nitrate constitutes the first example of a multicomponent carbazole syntrhesis. This reaction furnishes highly substituted and functionalized carbazole derivatives via a double annulation process that generates two C-C and two C-N bonds, with water as the only side product. Mechanistically, this process has some unusual features that include an intramolecular coupled hydrogenation-dehydrogenation process, the functionalization of a C-H group by direct attack onto a nitrogen function and a CAN-catalyzed reduction via hydride transfer from ethanol...
June 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28636363/distinct-protein-hydration-water-species-defined-by-spatially-resolved-spectra-of-intermolecular-vibrations
#14
Viren Sureshkumar Pattni, Tatiana Vasilevskaya, Walter Thiel, Matthias Heyden
In this molecular dynamics simulation study, we analyze intermolecular vibrations in the hydration shell of a solvated enyzme, the membrane type 1--matrix metalloproteinase, with high spatial resolution. Our approach allows us to characterize vibrational signatures of the local hydrogen bond network, the translational mobility of water molecules, as well as the molecular entropy, in specific local environments. Our study demonstrates the heterogeneity of water properties within the hydration shell of a complex biomolecule...
June 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28636350/integrating-a-semi-transparent-fullerene-free-organic-solar-cell-in-tandem-with-a-bivo4-photoanode-for-unassisted-solar-water-splitting
#15
Yuelin Peng, Gokul V Govindaraju, Dong Ki Lee, Kyoung-Shin Choi, Trisha L Andrew
We report an unassisted solar water splitting system powered by a diketopyrrolopyrrole (DPP)-containing semi-transparent organic solar cell. Two major merits of this fullerene-free solar cell enable its integration with a BiVO4 photoanode. First is the high open circuit voltage and high fill factor displayed by this single junction solar cell, which yields sufficient power to effect water splitting when serially-connected to an appropriate electrode/catalyst. Second, the wavelength-resolved photoaction spectrum of the DPP-based solar cell has minimal overlap with that of the BiVO4 photoanode, thus ensuring that light collection across these two components can be optimized...
June 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28636333/glycosaminoglycan-analysis-by-cryogenic-messenger-tagging-ir-spectroscopy-combined-with-ims-ms
#16
Neelam Khanal, Chiara Masellis, Michael Z Kamrath, David E Clemmer, Thomas R Rizzo
We combine ion mobility spectrometry with cryogenic, messenger-tagging, infrared spectroscopy and mass spectrometry to identify different isomeric disaccharides of chondroitin sulfate (CS) and heparan sulfate (HS), which are representatives of two major subclasses of glycosaminoglycans. Our analysis shows that while CS and HS disaccharide isomers have similar drift times, they can be uniquely distinguished by their vibrational spectrum between ~3200-3700 cm-1 due to their different OH hydrogen-bonding patterns...
June 21, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28636265/switch-of-c-h-activation-mechanism-for-full-selectivity-control-in-cobalt-iii-catalyzed-c-h-alkylations
#17
Daniel Zell, Markus Bursch, Valentin Müller, Stefan Grimme, Lutz Ackermann
Selectivity control in hydroarylation-based C-H alkylation has been dominated by steric interactions. In contrast, we unravel a conceptually distinct strategy that exploits the programmed switch in the C-H activation mechanism by means of cobalt catalysis, setting the stage for expedient C-H alkylations with unactivated alkenes. Detailed mechanistic studies provided compelling evidence for a programmable switch in the C-H activation mechanism from a linear-selective ligand-to-ligand hydrogen transfer (LLHT) to a branched-selective base-assisted internal electrophilic-type substitution (BIES)...
June 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28636148/magneto-structural-characterization-of-oxalamide-dihalo-bridged-copper-dimers-intra-and-interdimer-interactions-studied-by-single-crystal-esr-spectroscopy
#18
Dijana Zilic, Debdeep Maity, Mario Cetina, Kresimir Molcanov, Zoran Dzolic, Mirta Herak
The detailed single crystal electron spin resonance (ESR) analysis of oxalamide complexes with halogen-bridged copper dimers, supported by X-ray, magnetic susceptibility and powder ESR studies, is reported. Four complexes with two different ligands were synthesized: [CuLA(μ-X)]₂ and [CuLV(μ-X)]₂, where LA = N-(L-alanine methyl ester)-N'-((2-pyridine-2-yl)methyl)oxalamide and LV=N-(L-valine methyl ester)-N'-((2-pyridine-2-yl)methyl)oxalamide, while X=Cl or Br. X-ray analysis shows that geometry at each copper(II) ion is square pyramidal while two pyramids share one base-to-apex edge with parallel basal planes...
June 21, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28636035/development-of-air-stable-hydrogen-evolution-catalysts
#19
Biswajit Mondal, Abhishek Dey
Obtaining abundant pure hydrogen by reduction of water has an important implication in the development of clean and renewable energy. Hence research focused on the development of non-noble metal based facile and energy efficient catalysts for proton reduction is on the rise. However, for practical utilization, it is necessary that these complexes function unabated in the presence of atmospheric oxygen and other common contaminants in abundant water sources. There has been very little activity towards the development of oxygen-tolerant hydrogen producing catalysts...
June 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28636013/new-insights-into-the-solubility-of-graphene-oxide-in-water-and-alcohols
#20
Vadim V Neklyudov, Nail R Khafizov, Igor A Sedov, Ayrat M Dimiev
One of the main advantages of graphene oxide (GO) over its non-oxidized counterpart is its ability to form stable solutions in water and some organic solvents. At the same time, the nature of GO solutions is not completely understood; the existing data are scarce and controversial. Here, we demonstrate that the solubility of GO, and the stability of the as-formed solutions depend not just on the solute and solvent cohesion parameters, as commonly believed, but mostly on the chemical interactions at the GO/solvent interface...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
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