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Aurélie Fossey-Jouenne, Carine Vergne-Vaxelaire, Anne Zaparucha
Amino alcohols are versatile compounds with a wide range of applications. For instance, they have been used as chiral scaffolds in organic synthesis. Their synthesis by conventional organic chemistry often requires tedious multi-step synthesis processes, with difficult control of the stereochemical outcome. We present a protocol to enzymatically synthetize amino alcohols starting from the readily available L-lysine in 48 h. This protocol combines two chemical reactions that are very difficult to conduct by conventional organic synthesis...
February 16, 2018: Journal of Visualized Experiments: JoVE
Amit A Vernekar, Gilles Berger, Anna E Czapar, Frank A Veliz, David I Wang, Nicole F Steinmetz, Stephen J Lippard
Efficient loading of drugs in novel delivery agents has the potential to substantially improve therapy by targeting the diseased tissue while avoiding unwanted side effects. Here we report the first systematic study of the loading mechanism of phenanthriplatin and its analogs into tobacco mosaic virus (TMV), previously used by our group as an efficient carrier for anticancer drug delivery. A detailed investigation of the preferential uptake of phenanthriplatin in its aquated form (∼2000 molecules per TMV particle versus ∼1000 for the chlorido form) is provided...
March 19, 2018: Journal of the American Chemical Society
Anna Żądło-Dobrowolska, Nina G Schmidt, Wolfgang Kroutil
Amide bond formation has considerable significance in synthetic chemistry. Although the C-acyltransferase from Pseudomonas protegens has been found to catalyze C-C bond formation in nature as well as in in vitro experiments with non-natural substrates, it is now shown that the enzyme is also able to catalyze amide formation using aniline derivatives as substrates with promiscuous activity. Importantly, the amide formation was enabled in aqueous buffer. Identifying phenyl acetate as the most suitable acetyl donor, the products were obtained with up to >99% conversion and up to 99% isolated yield...
March 19, 2018: Chemical Communications: Chem Comm
Chiaki Yabuki, Akitomo Rikuta, Ryosuke Murayama, Syunsuke Akiba, Soshi Suzuki, Toshiki Takamizawa, Hiroyasu Kurokawa, Masashi Miyazaki
The purpose of this study was to investigate the effect of acid erosion on the bonding performance of universal adhesives. Freshly extracted bovine teeth were cut into enamel slabs and assigned to either the Er or the control group. Specimens in the Er group were immersed in citric acid solution (pH 2.1) twice a day and stored in artificial saliva, while control specimens were simply stored in artificial saliva. Differences in the mean values between the control and Er groups were greater than expected, despite accounting for the effect of differences in the adhesive systems (p=0...
March 17, 2018: Dental Materials Journal
Hao Yu, Zhen Li, Carsten Bolm
A copper-catalyzed sulfoxidation of benzylic C-H bonds by nondirected oxidative C(sp3 )-H activation was developed. The process proceeds via sulfenate anions, which are generated by base-triggered elimination of β-sulfinyl esters and benzyl radicals. The functional group tolerance is high, and the product yields are good.
March 19, 2018: Organic Letters
Lei Zhang, Beiqi Sun, Qianyi Liu, Fanyang Mo
We describe here an operationally simple and straightforward synthesis method for a series of diverse 4,5-disubstituted 1,2,3-thiadiazoles via the nucleophilic addition of α-diazo carbonyl compounds to carbon disulfide. This method features using abundant and inexpensive carbon disulfide with mild reaction conditions.
March 19, 2018: Journal of Organic Chemistry
Ling Yang, Wei-Wei Ji, E Lin, Ji-Lin Li, Wen-Xin Fan, Qingjiang Li, Honggen Wang
A reductive cross-coupling of gem-difluoroalkenes with diverse unactivated and heteroatom substituted olefins through a Fe-catalyzed hydrogen atom transfer (HAT) strategy is reported. Different from the previous HAT-type olefin cross-coupling reactions, the presence of a fluorine atom in the molecule results in a stereoselective β-F cleavage, leading to a C(sp2 )-C(sp3 ) bond formation. A wide variety of alkylated monofluoroalkenes were obtained in good efficiency with excellent Z selectivity under air- and water-tolerant reaction conditions...
March 19, 2018: Organic Letters
Arup Tarai, Jubaraj B Baruah
A series of mononuclear complexes of divalent nickel and zinc with N-(4-methoxyphenyl)-2-(propan-2-ylidene)hydrazine carbothioamide (H2Lmethoxy) as well as with N-(4-nitrophenyl)-2-(propan-2-ylidene)hydrazine carbothioamide (H2Lnitro) have been structurally characterised. Among these two ligands, H2Lnitro formed an analogous copper(ii) complex to that of nickel and zinc, whereas H2Lmethoxy undergoes a catalytic cyclisation reaction in the presence of copper(ii) nitrate trihydrate. Control experiments based on ESR have revealed that copper(ii) is reduced to copper(i) and reverts back to copper(ii) as the cyclisation reaction proceeds, generating a catalytic reaction...
March 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
R Walker, D Pociecha, J P Abberley, A Martinez-Felipe, D A Paterson, E Forsyth, G B Lawrence, P A Henderson, J M D Storey, E Gorecka, C T Imrie
The spontaneous formation of a chiral phase via molecular recognition in a system consisting of achiral components is reported. Specifically, the liquid crystalline behaviour of two molecular complexes assembled by hydrogen bonding between a stilbazole-based template and alkoxybenzoic acids has been characterised. The complexes exhibit the heliconical twist-bend nematic phase (NTB) over a broad temperature range despite the hydrogen-bond acceptor not being liquid crystalline and the donor exhibiting the conventional achiral nematic phase...
March 19, 2018: Chemical Communications: Chem Comm
Jannis Köhler, Jegor Ruschke, Katja Bettina Ferenz, Cemal Esen, Michael Kirsch, Andreas Ostendorf
Albumin-derived perfluorocarbon-based capsules are promising as artificial oxygen carriers with high solubility. However, these capsules have to be studied further to allow initial human clinical tests. The aim of this paper is to provide and characterize a holographic optical tweezer to enable contactless trapping and moving of individual capsules in an environment that mimics physiological (in vivo) conditions most effectively in order to learn more about the artificial oxygen carrier behavior in blood plasma without recourse to animal experiments...
February 1, 2018: Biomedical Optics Express
Soroush Safaei, Pablo J Blanco, Lucas O Müller, Leif R Hellevik, Peter J Hunter
We propose a detailed CellML model of the human cerebral circulation that runs faster than real time on a desktop computer and is designed for use in clinical settings when the speed of response is important. A lumped parameter mathematical model, which is based on a one-dimensional formulation of the flow of an incompressible fluid in distensible vessels, is constructed using a bond graph formulation to ensure mass conservation and energy conservation. The model includes arterial vessels with geometric and anatomical data based on the ADAN circulation model...
2018: Frontiers in Physiology
Sung-Hoon Kim, Chan-Jin Park, Lee-Ra Cho, Yoon-Hyuk Huh
STATEMENT OF PROBLEM: Little information is available for the strength of bonding between zirconia and lithium disilicate as affected by surface pretreatment methods. PURPOSE: The purpose of this in vitro study was to investigate the shear bond strength (SBS) between zirconia core and lithium disilicate (LS2 ) veneered ceramic after surface pretreatments. MATERIAL AND METHODS: Fully sintered yttrium oxide partially stabilized tetragonal zirconia (Y-TZP) disk specimens were fabricated from zirconia ceramic materials...
March 15, 2018: Journal of Prosthetic Dentistry
Ting Zhang, Liping Wang, Ying Bao, Qi Yang, Lina Zhou, Hongxun Hao, Chuang Xie
Polymorphic forms of etoricoxib have been reported in the literature and form I was considered to be the most stable one. However, in this work, it was found that form I and form V are enantiotropic by DSC analysis, solubility measurements and solution-mediated polymorphic transformation experiments with form V being more stable than form I at room temperature. Thermodynamic transition temperature is determined as (353.45 ± 0.10) K. Besides, form V would transform to form I with the seeding effect of form I at high temperature below the melting point of form V...
March 15, 2018: Journal of Pharmaceutical Sciences
Margherita Sosio, Eleonora Gaspari, Marianna Iorio, Silvia Pessina, Marnix H Medema, Alice Bernasconi, Matteo Simone, Sonia I Maffioli, Richard H Ebright, Stefano Donadio
Pseudouridimycin (PUM) is a selective nucleoside-analog inhibitor of bacterial RNA polymerase with activity against Gram-positive and Gram-negative bacteria. PUM, produced by Streptomyces sp. ID38640, consists of a formamidinylated, N-hydroxylated Gly-Gln dipeptide conjugated to 5'-aminopseudouridine. We report the characterization of the PUM gene cluster. Bioinformatic analysis and mutational knockouts of pum genes with analysis of accumulated intermediates, define the PUM biosynthetic pathway. The work provides the first biosynthetic pathway of a C-nucleoside antibiotic and reveals three unexpected features: production of free pseudouridine by the dedicated pseudouridine synthase, PumJ; nucleoside activation by specialized oxidoreductases and aminotransferases; and peptide-bond formation by amide ligases...
February 26, 2018: Cell Chemical Biology
María M Adeva-Andany, Natalia Carneiro-Freire, Mónica Seco-Filgueira, Carlos Fernández-Fernández, David Mouriño-Bayolo
Mitochondrial β-oxidation of fatty acids generates acetyl-coA, NADH and FADH2 . Acyl-coA synthetases catalyze the binding of fatty acids to coenzyme A to form fatty acyl-coA thioesters, the first step in the intracellular metabolism of fatty acids. l-carnitine system facilitates the transport of fatty acyl-coA esters across the mitochondrial membrane. Carnitine palmitoyltransferase-1 transfers acyl groups from coenzyme A to l-carnitine, forming acyl-carnitine esters at the outer mitochondrial membrane. Carnitine acyl-carnitine translocase exchanges acyl-carnitine esters that enter the mitochondria, by free l-carnitine...
March 15, 2018: Mitochondrion
Xin Meng, Harrison Sejoon Kim, Antonio T Lucero, Su Min Hwang, Joy S Lee, Young-Chul Byun, Jiyoung Kim, Byung Keun Hwang, Xiaobing Zhou, Jeanette Young, Michael Telgenhoff
In this work, a novel chlorodisilane precursor, pentachlorodisilane (PCDS, HSi2 Cl5 ), was investigated for the growth of SiNx via hollow cathode plasma-enhanced atomic layer deposition (PEALD). Well-defined self-limiting growth behavior was successfully demonstrated over the growth temperature range of 270-360 °C. At identical process conditions, PCDS not only demonstrated approximately >20% higher growth per cycle (GPC) than that of a commercially available chlorodisilane precursor, hexachlorodisilane (HCDS, Si2 Cl6 ), but also delivered a better or at least comparable film quality determined by characterizing the refractive index, wet etch rate, and density of the films...
March 17, 2018: ACS Applied Materials & Interfaces
Adrien J Göttle, Marc T M Koper
This work provides insights to understand the selectivity during the reduction of CO2 with metalloporphyrin (MP) catalysts (the porphyrin complex with porphin ligand and the metal-centers Fe, Co, Ni, Cu, Zn, Rh, Pd, Ag, Cd, Ga, In and Sn were considered). The attack of a nucleophile on the carbon of the CO2 appears as a necessary event to trigger the catalytic reaction, and the nature of this nucleophile determines the selectivity between CO (or further reduced species) and HCOOH/HCOO-. For MP, the relevant electrogenerated nucleophiles are the reduced metal-center, the metal-hydride or the phlorin-hydride ligand...
March 18, 2018: Journal of the American Chemical Society
Michael C Owen, Waldemar Kulig, Tomasz Rog, Ilpo Vattulainen, Birgit Strodel
In an effort to delineate how cholesterol protects membrane structure under oxidative stress conditions, we monitored the changes to the structure of lipid bilayers comprising 30 mol% cholesterol and an increasing concentration of Class B oxidized 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) glycerophospholipids, namely, 1-palmitoyl-2-(9'-oxo-nonanoyl)-sn-glycero-3-phosphocholine (PoxnoPC), and 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC), using atomistic molecular dynamics simulations. Increasing the content of oxidized phospholipids (oxPLs) from 0 to 60 mol% oxPL resulted in a characteristic reduction in bilayer thickness and increase in area per lipid, thereby increasing the exposure of the membrane hydrophobic region to water...
March 17, 2018: Journal of Membrane Biology
Zhiyong Yan, Feng Wang, Pingye Deng, Yu Wang, Kai Cai, Yanhui Chen, Zonghua Wang, Yang Liu
In this work, a novel and sensitive electrogenerated chemiluminescence (ECL) biosensor for protein kinase A (PKA) activity analysis and relevant inhibitor screening was proposed based on bimetallic catalysis signal amplification and recognition of Au and Pt nanoparticles loaded metal-organic frameworks (Au&Pt@UiO-66) nanocomposite. After being phosphorylated by PKA in the presence of ATP, Au&Pt@UiO-66 probes were specifically chelated to the modified electrode by forming Zr-O-P bonds between the surface defects of UiO-66 and the phosphorylated kemptide...
March 5, 2018: Biosensors & Bioelectronics
Xiujuan Kong, Zihao Wu, Ziran Ren, Kaiheng Guo, Shaodong Hou, Zhechao Hua, Xuchun Li, Jingyun Fang
Degradation of three lipid regulators, i.e., gemfibrozil, bezafibrate and clofibric acid, by a UV/chlorine treatment was systematically investigated. The chlorine oxide radical (ClO• ) played an important role in the degradation of gemfibrozil and bezafibrate with second-order rate constants of 4.2 (±0.3) × 108  M-1  s-1 and 3.6 (±0.1) × 107  M-1  s-1 , respectively, whereas UV photolysis and the hydroxyl radical (HO• ) mainly contributed to the degradation of clofibric acid. The first-order rate constants (k') for the degradation of gemfibrozil and bezafibrate increased linearly with increasing chlorine dosage, primarily due to the linear increase in the ClO• concentration...
March 6, 2018: Water Research
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