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ACS Central Science

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https://www.readbyqxmd.com/read/28149957/illuminating-phenylazopyridines-to-photoswitch-metabotropic-glutamate-receptors-from-the-flask-to-the-animals
#1
Xavier Gómez-Santacana, Silvia Pittolo, Xavier Rovira, Marc Lopez, Charleine Zussy, James A R Dalton, Adèle Faucherre, Chris Jopling, Jean-Philippe Pin, Francisco Ciruela, Cyril Goudet, Jesús Giraldo, Pau Gorostiza, Amadeu Llebaria
Phenylazopyridines are photoisomerizable compounds with high potential to control biological functions with light. We have obtained a series of phenylazopyridines with light dependent activity as negative allosteric modulators (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5). Here we describe the factors needed to achieve an operational molecular photoisomerization and its effective translation into in vitro and in vivo receptor photoswitching, which includes zebrafish larva motility and the regulation of the antinociceptive effects in mice...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149956/discovery-and-investigation-of-natural-editing-function-against-artificial-amino-acids-in-protein-translation
#2
Jan-Stefan Völler, Morana Dulic, Ulla I M Gerling-Driessen, Hernan Biava, Tobias Baumann, Nediljko Budisa, Ita Gruic-Sovulj, Beate Koksch
Fluorine being not substantially present in the chemistry of living beings is an attractive element in tailoring novel chemical, biophysical, and pharmacokinetic properties of peptides and proteins. The hallmark of ribosome-mediated artificial amino acid incorporation into peptides and proteins is a broad substrate tolerance, which is assumed to rely on the absence of evolutionary pressure for efficient editing of artificial amino acids. We used the well-characterized editing proficient isoleucyl-tRNA synthetase (IleRS) from Escherichia coli to investigate the crosstalk of aminoacylation and editing activities against fluorinated amino acids...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149955/lewis-acid-induced-toggle-from-ir-ii-to-ir-iv-pathways-in-photocatalytic-reactions-synthesis-of-thiomorpholines-and-thiazepanes-from-aldehydes-and-slap-reagents
#3
Sheng-Ying Hsieh, Jeffrey W Bode
Redox neutral photocatalytic transformations often require careful pairing of the substrates and photoredox catalysts in order to achieve a catalytic cycle. This can limit the range of viable transformations, as we recently observed in attempting to extend the scope of the photocatalytic synthesis of N-heterocycles using silicon amine protocol (SLAP) reagents to include starting materials that require higher oxidation potentials. We now report that the inclusion of Lewis acids in photocatalytic reactions of organosilanes allows access to a distinct reaction pathway featuring an Ir(III)*/Ir(IV) couple instead of the previously employed Ir(III)*/Ir(II) pathway, enabling the transformation of aromatic and aliphatic aldehydes to thiomorpholines and thiazepanes...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149954/colloidal-covalent-organic-frameworks
#4
Brian J Smith, Lucas R Parent, Anna C Overholts, Peter A Beaucage, Ryan P Bisbey, Anton D Chavez, Nicky Hwang, Chiwoo Park, Austin M Evans, Nathan C Gianneschi, William R Dichtel
Covalent organic frameworks (COFs) are two- or three-dimensional (2D or 3D) polymer networks with designed topology and chemical functionality, permanent porosity, and high surface areas. These features are potentially useful for a broad range of applications, including catalysis, optoelectronics, and energy storage devices. But current COF syntheses offer poor control over the material's morphology and final form, generally providing insoluble and unprocessable microcrystalline powder aggregates. COF polymerizations are often performed under conditions in which the monomers are only partially soluble in the reaction solvent, and this heterogeneity has hindered understanding of their polymerization or crystallization processes...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149953/rechargeable-sodium-all-solid-state-battery
#5
Weidong Zhou, Yutao Li, Sen Xin, John B Goodenough
A reversible plating/stripping of a dendrite-free metallic-sodium anode with a reduced anode/ceramic interfacial resistance is created by a thin interfacial interlayer formed in situ or by the introduction of a dry polymer film. Wetting of the sodium on the interfacial interlayer suppresses dendrite formation and growth at different discharge/charge C-rates. All-solid-state batteries were obtained with a high cycling stability and Coulombic efficiency at 65 °C.
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149952/scalable-synthesis-of-thapsigargin
#6
Hang Chu, Joel M Smith, Jakob Felding, Phil S Baran
Total syntheses of the complex, highly oxygenated sesquiterpenes thapsigargin (1) and nortrilobolide (2) are presented. Access to analogues of these promising bioactive natural products has been limited to tedious isolation and semisynthetic efforts. Elegant prior total syntheses demonstrated the feasibility of creating these entitites in 36-42 step processes. The currently reported route proceeds in a scalable and more concise fashion by utilizing two-phase terpene synthesis logic. Salient features of the work include application of the classic photosantonin rearrangement and precisely choreographed installation of the multiple oxygenations present on the guaianolide skeleton...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149951/unravelling-photochemical-relationships-among-natural-products-from-aplysia-dactylomela
#7
Bryan S Matsuura, Patrick Kölle, Dirk Trauner, Regina de Vivie-Riedle, Robin Meier
Aplydactone (1) is a brominated ladderane sesquiterpenoid that was isolated from the sea hare Aplysia dactylomela together with the chamigranes dactylone (2) and 10-epi-dactylone (3). Given the habitat of A. dactylomela, it seems likely that 1 is formed from 2 through a photochemical [2 + 2] cycloaddition. Here, we disclose a concise synthesis of 1, 2, and 3 that was guided by excited state theory and relied on several highly stereoselective transformations. Our experiments and calculations confirm the photochemical origin of 1 and explain why it is formed as the sole isomer...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149950/metal-organic-framework-supported-cobalt-catalysts-for-the-oxidative-dehydrogenation-of-propane-at-low-temperature
#8
Zhanyong Li, Aaron W Peters, Varinia Bernales, Manuel A Ortuño, Neil M Schweitzer, Matthew R DeStefano, Leighanne C Gallington, Ana E Platero-Prats, Karena W Chapman, Christopher J Cramer, Laura Gagliardi, Joseph T Hupp, Omar K Farha
Zr-based metal-organic frameworks (MOFs) have been shown to be excellent catalyst supports in heterogeneous catalysis due to their exceptional stability. Additionally, their crystalline nature affords the opportunity for molecular level characterization of both the support and the catalytically active site, facilitating mechanistic investigations of the catalytic process. We describe herein the installation of Co(II) ions to the Zr6 nodes of the mesoporous MOF, NU-1000, via two distinct routes, namely, solvothermal deposition in a MOF (SIM) and atomic layer deposition in a MOF (AIM), denoted as Co-SIM+NU-1000 and Co-AIM+NU-1000, respectively...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149949/cyp450-enzymes-effect-oxygen-dependent-reduction-of-azide-based-fluorogenic-dyes
#9
Liam J O'Connor, Ishna N Mistry, Sarah L Collins, Lisa K Folkes, Graham Brown, Stuart J Conway, Ester M Hammond
Azide-containing compounds have broad utility in organic synthesis and chemical biology. Their use as powerful tools for the labeling of biological systems in vitro has enabled insights into complex cellular functions. To date, fluorogenic azide-containing compounds have primarily been employed in the context of click chemistry and as sensitive functionalities for hydrogen sulfide detection. Here, we report an alternative use of this functionality: as fluorogenic probes for the detection of depleted oxygen levels (hypoxia)...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149948/mechanochemistry-a-force-of-synthesis
#10
REVIEW
Jean-Louis Do, Tomislav Friščić
The past decade has seen a reawakening of solid-state approaches to chemical synthesis, driven by the search for new, cleaner synthetic methodologies. Mechanochemistry, i.e., chemical transformations initiated or sustained by mechanical force, has been advancing particularly rapidly, from a laboratory curiosity to a widely applicable technique that not only enables a cleaner route to chemical transformations but offers completely new opportunities in making and screening for molecules and materials. This Outlook provides a brief overview of the recent achievements and opportunities created by mechanochemistry, including access to materials, molecular targets, and synthetic strategies that are hard or even impossible to access by conventional means...
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149947/oxidative-dehydrogenation-of-propane-in-the-realm-of-metal-organic-frameworks
#11
Maciej Damian Korzyński, Mircea Dincă
No abstract text is available yet for this article.
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149946/dust-unsettled
#12
Janet Pelley
No abstract text is available yet for this article.
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149945/a-conversation-with-sascha-drewlo
#13
Erika Gebel Berg
No abstract text is available yet for this article.
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28149944/a-peek-into-the-world-behind-the-submit-button
#14
EDITORIAL
Miranda A Paley
No abstract text is available yet for this article.
January 25, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28058286/close-correlation-of-monoamine-oxidase-activity-with-progress-of-alzheimer-s-disease-in-mice-observed-by-in-vivo-two-photon-imaging
#15
Dokyoung Kim, Sung Hoon Baik, Seokjo Kang, Seo Won Cho, Juryang Bae, Moon-Yong Cha, Michael J Sailor, Inhee Mook-Jung, Kyo Han Ahn
Monoamine oxidases (MAOs) play an important role in Alzheimer's disease (AD) pathology. We report in vivo comonitoring of MAO activity and amyloid-β (Aβ) plaques dependent on the aging of live mice with AD, using a two-photon fluorescence probe. The probe under the catalytic action of MAO produces a dipolar fluorophore that senses Aβ plaques, a general AD biomarker, enabling us to comonitor the enzyme activity and the progress of AD indicated by Aβ plaques. The results show that the progress of AD has a close correlation with MAO activity, which can be categorized into three stages: slow initiation stage up to three months, an aggressive stage, and a saturation stage from nine months...
December 28, 2016: ACS Central Science
https://www.readbyqxmd.com/read/28058285/large-hyperpolarizabilities-at-telecommunication-relevant-wavelengths-in-donor-acceptor-donor-nonlinear-optical-chromophores
#16
Animesh Nayak, Jaehong Park, Kurt De Mey, Xiangqian Hu, Timothy V Duncan, David N Beratan, Koen Clays, Michael J Therien
Octopolar D2-symmetric chromophores, based on the MPZnM supermolecular motif in which (porphinato)zinc(II) (PZn) and ruthenium(II) polypyridyl (M) structural units are connected via ethyne linkages, were synthesized. These structures take advantage of electron-rich meso-arylporphyrin or electron-poor meso-(perfluoroalkyl)porphyrin macrocycles, unsubstituted terpyridyl and 4'-pyrrolidinyl-2,2';6',2″-terpyridyl ligands, and modulation of metal(II) polypyridyl-to-(porphinato)zinc connectivity, to probe how electronic and geometric factors impact the measured hyperpolarizability...
December 28, 2016: ACS Central Science
https://www.readbyqxmd.com/read/28058284/why-do-membranes-of-some-unhealthy-cells-adopt-a-cubic-architecture
#17
Qi Xiao, Zhichun Wang, Dewight Williams, Pawaret Leowanawat, Mihai Peterca, Samuel E Sherman, Shaodong Zhang, Daniel A Hammer, Paul A Heiney, Steven R King, David M Markovitz, Sabine André, Hans-Joachim Gabius, Michael L Klein, Virgil Percec
Nonlamellar lipid arrangements, including cubosomes, appear in unhealthy cells, e.g., when they are subject to stress, starvation, or viral infection. The bioactivity of cubosomes-nanoscale particles exhibiting bicontinuous cubic structures-versus more common vesicles is an unexplored area due to lack of suitable model systems. Here, glycodendrimercubosomes (GDCs)-sugar-presenting cubosomes assembled from Janus glycodendrimers by simple injection into buffer-are proposed as mimics of biological cubic membranes...
December 28, 2016: ACS Central Science
https://www.readbyqxmd.com/read/28058283/insight-into-transmetalation-enables-cobalt-catalyzed-suzuki-miyaura-cross-coupling
#18
Jamie M Neely, Máté J Bezdek, Paul J Chirik
Among the fundamental transformations that comprise a catalytic cycle for cross coupling, transmetalation from the nucleophile to the metal catalyst is perhaps the least understood. Optimizing this elementary step has enabled the first example of a cobalt-catalyzed Suzuki-Miyaura cross coupling between aryl triflate electrophiles and heteroaryl boron nucleophiles. Key to this discovery was the preparation and characterization of a new class of tetrahedral, high-spin bis(phosphino)pyridine cobalt(I) alkoxide and aryloxide complexes, ((iPr)PNP)CoOR, and optimizing their reactivity with 2-benzofuranylBPin (Pin = pinacolate)...
December 28, 2016: ACS Central Science
https://www.readbyqxmd.com/read/28058282/protein-degradation-by-in-cell-self-assembly-of-proteolysis-targeting-chimeras
#19
Honorine Lebraud, David J Wright, Christopher N Johnson, Tom D Heightman
Selective degradation of proteins by proteolysis targeting chimeras (PROTACs) offers a promising potential alternative to protein inhibition for therapeutic intervention. Current PROTAC molecules incorporate a ligand for the target protein, a linker, and an E3 ubiquitin ligase recruiting group, which bring together target protein and ubiquitinating machinery. Such hetero-bifunctional molecules require significant linker optimization and possess high molecular weight, which can limit cellular permeation, solubility, and other drug-like properties...
December 28, 2016: ACS Central Science
https://www.readbyqxmd.com/read/28058281/unusual-base-pairing-interactions-in-monomer-template-complexes
#20
Wen Zhang, Chun Pong Tam, Jiawei Wang, Jack W Szostak
Many high-resolution crystal structures have contributed to our understanding of the reaction pathway for catalysis by DNA and RNA polymerases, but the structural basis of nonenzymatic template-directed RNA replication has not been studied in comparable detail. Here we present crystallographic studies of the binding of ribonucleotide monomers to RNA primer-template complexes, with the goal of improving our understanding of the mechanism of nonenzymatic RNA copying, and of catalysis by polymerases. To explore how activated ribonucleotides recognize and bind to RNA templates, we synthesized an unreactive phosphonate-linked pyrazole analogue of guanosine 5'-phosphoro-2-methylimidazolide (2-MeImpG), a highly activated nucleotide that has been used extensively to study nonenzymatic primer extension...
December 28, 2016: ACS Central Science
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