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Nature Chemistry

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https://www.readbyqxmd.com/read/28644485/probing-the-early-stages-of-photoreception-in-photoactive-yellow-protein-with-ultrafast-time-domain-raman-spectroscopy
#1
Hikaru Kuramochi, Satoshi Takeuchi, Kento Yonezawa, Hironari Kamikubo, Mikio Kataoka, Tahei Tahara
Unveiling the nuclear motions of photoreceptor proteins in action is a crucial goal in protein science in order to understand their elaborate mechanisms and how they achieve optimal selectivity and efficiency. Previous studies have provided detailed information on the structures of intermediates that appear during the later stages (>ns) of such photoreception cycles, yet the initial events immediately after photoabsorption remain unclear because of experimental challenges in monitoring nuclear rearrangements on ultrafast timescales, including protein-specific low-frequency motions...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644483/pasteur-and-the-art-of-chirality
#2
Joseph Gal
No abstract text is available yet for this article.
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644482/one-thousand-fold-enhancement-of-high-field-liquid-nuclear-magnetic-resonance-signals-at-room-temperature
#3
Guoquan Liu, Marcel Levien, Niels Karschin, Giacomo Parigi, Claudio Luchinat, Marina Bennati
Nuclear magnetic resonance (NMR) is a fundamental spectroscopic technique for the study of biological systems and materials, molecular imaging and the analysis of small molecules. It detects interactions at very low energies and is thus non-invasive and applicable to a variety of targets, including animals and humans. However, one of its most severe limitations is its low sensitivity, which stems from the small interaction energies involved. Here, we report that dynamic nuclear polarization in liquid solution and at room temperature can enhance the NMR signal of (13)C nuclei by up to three orders of magnitude at magnetic fields of ∼3 T...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644481/redox-controlled-potassium-intercalation-into-two-polyaromatic-hydrocarbon-solids
#4
F Denis Romero, M J Pitcher, C I Hiley, G F S Whitehead, S Kar, A Y Ganin, D Antypov, C Collins, M S Dyer, G Klupp, R H Colman, K Prassides, M J Rosseinsky
Alkali metal intercalation into polyaromatic hydrocarbons (PAHs) has been studied intensely after reports of superconductivity in a number of potassium- and rubidium-intercalated materials. There are, however, no reported crystal structures to inform our understanding of the chemistry and physics because of the complex reactivity of PAHs with strong reducing agents at high temperature. Here we present the synthesis of crystalline K2Pentacene and K2Picene by a solid-solid insertion protocol that uses potassium hydride as a redox-controlled reducing agent to access the PAH dianions, and so enables the determination of their crystal structures...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644480/a-polymer-nanoparticle-with-engineered-affinity-for-a-vascular-endothelial-growth-factor-vegf165
#5
Hiroyuki Koide, Keiichi Yoshimatsu, Yu Hoshino, Shih-Hui Lee, Ai Okajima, Saki Ariizumi, Yudai Narita, Yusuke Yonamine, Adam C Weisman, Yuri Nishimura, Naoto Oku, Yoshiko Miura, Kenneth J Shea
Protein affinity reagents are widely used in basic research, diagnostics and separations and for clinical applications, the most common of which are antibodies. However, they often suffer from high cost, and difficulties in their development, production and storage. Here we show that a synthetic polymer nanoparticle (NP) can be engineered to have many of the functions of a protein affinity reagent. Polymer NPs with nM affinity to a key vascular endothelial growth factor (VEGF165) inhibit binding of the signalling protein to its receptor VEGFR-2, preventing receptor phosphorylation and downstream VEGF165-dependent endothelial cell migration and invasion into the extracellular matrix...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644476/enantioselective-intermolecular-benzylic-c-h-amination-catalysed-by-an-engineered-iron-haem-enzyme
#6
Christopher K Prier, Ruijie K Zhang, Andrew R Buller, Sabine Brinkmann-Chen, Frances H Arnold
C-H bonds are ubiquitous structural units of organic molecules. Although these bonds are generally considered to be chemically inert, the recent emergence of methods for C-H functionalization promises to transform the way synthetic chemistry is performed. The intermolecular amination of C-H bonds represents a particularly desirable and challenging transformation for which no efficient, highly selective, and renewable catalysts exist. Here we report the directed evolution of an iron-containing enzymatic catalyst-based on a cytochrome P450 monooxygenase-for the highly enantioselective intermolecular amination of benzylic C-H bonds...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644475/post-translational-modification-of-ribosomally-synthesized-peptides-by-a-radical-sam-epimerase-in-bacillus-subtilis
#7
Alhosna Benjdia, Alain Guillot, Pauline Ruffié, Jérôme Leprince, Olivier Berteau
Ribosomally synthesized peptides are built out of L-amino acids, whereas D-amino acids are generally the hallmark of non-ribosomal synthetic processes. Here we show that the model bacterium Bacillus subtilis is able to produce a novel type of ribosomally synthesized and post-translationally modified peptide that contains D-amino acids, and which we propose to call epipeptides. We demonstrate that a two [4Fe-4S]-cluster radical S-adenosyl-L-methionine (SAM) enzyme converts L-amino acids into their D-counterparts by catalysing Cα-hydrogen-atom abstraction and using a critical cysteine residue as the hydrogen-atom donor...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644474/%C3%AF-electron-s%C3%A2-%C3%A2-%C3%A2-quantum-spin-liquid-state-in-an-ionic-polyaromatic-hydrocarbon
#8
Yasuhiro Takabayashi, Melita Menelaou, Hiroyuki Tamura, Nayuta Takemori, Takashi Koretsune, Aleš Štefančič, Gyöngyi Klupp, A Johan C Buurma, Yusuke Nomura, Ryotaro Arita, Denis Arčon, Matthew J Rosseinsky, Kosmas Prassides
Molecular solids with cooperative electronic properties based purely on π electrons from carbon atoms offer a fertile ground in the search for exotic states of matter, including unconventional superconductivity and quantum magnetism. The field was ignited by reports of high-temperature superconductivity in materials obtained by the reaction of alkali metals with polyaromatic hydrocarbons, such as phenanthrene and picene, but the composition and structure of any compound in this family remained unknown. Here we isolate the binary caesium salts of phenanthrene, Cs(C14H10) and Cs2(C14H10), to show that they are multiorbital strongly correlated Mott insulators...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644470/rapid-heteroatom-transfer-to-arylmetals-utilizing-multifunctional-reagent-scaffolds
#9
Hongyin Gao, Zhe Zhou, Doo-Hyun Kwon, James Coombs, Steven Jones, Nicole Erin Behnke, Daniel H Ess, László Kürti
Arylmetals are highly valuable carbon nucleophiles that are readily and inexpensively prepared from aryl halides or arenes and widely used on both laboratory and industrial scales to react directly with a wide range of electrophiles. Although C-C bond formation has been a staple of organic synthesis, the direct transfer of primary amino (-NH2) and hydroxyl (-OH) groups to arylmetals in a scalable and environmentally friendly fashion remains a formidable synthetic challenge because of the absence of suitable heteroatom-transfer reagents...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644469/cooperative-polymerization-of-%C3%AE-helices-induced-by-macromolecular-architecture
#10
Ryan Baumgartner, Hailin Fu, Ziyuan Song, Yao Lin, Jianjun Cheng
Catalysis observed in enzymatic processes and protein polymerizations often relies on the use of supramolecular interactions and the organization of functional elements in order to gain control over the spatial and temporal elements of fundamental cellular processes. Harnessing these cooperative interactions to catalyse reactions in synthetic systems, however, remains challenging due to the difficulty in creating structurally controlled macromolecules. Here, we report a polypeptide-based macromolecule with spatially organized α-helices that can catalyse its own formation...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644468/observation-of-electron-transfer-mediated-decay-in-aqueous-solution
#11
Isaak Unger, Robert Seidel, Stephan Thürmer, Marvin N Pohl, Emad F Aziz, Lorenz S Cederbaum, Eva Muchová, Petr Slavíček, Bernd Winter, Nikolai V Kryzhevoi
Photoionization is at the heart of X-ray photoelectron spectroscopy (XPS), which gives access to important information on a sample's local chemical environment. Local and non-local electronic decay after photoionization-in which the refilling of core holes results in electron emission from either the initially ionized species or a neighbour, respectively-have been well studied. However, electron-transfer-mediated decay (ETMD), which involves the refilling of a core hole by an electron from a neighbouring species, has not yet been observed in condensed phase...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644466/characterization-of-a-selenocysteine-ligated-p450-compound-i-reveals-direct-link-between-electron-donation-and-reactivity
#12
Elizabeth L Onderko, Alexey Silakov, Timothy H Yosca, Michael T Green
Strong electron-donation from the axial thiolate ligand of cytochrome P450 has been proposed to increase the reactivity of compound I with respect to C-H bond activation. However, it has proven difficult to test this hypothesis, and a direct link between reactivity and electron donation has yet to be established. To make this connection, we have prepared a selenolate-ligated cytochrome P450 compound I intermediate. This isoelectronic perturbation allows for direct comparisons with the wild-type enzyme. Selenium incorporation was achieved using a cysteine auxotrophic Escherichia coli strain...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644464/a-synthetic-ion-transporter-that-disrupts-autophagy-and-induces-apoptosis-by-perturbing-cellular-chloride-concentrations
#13
Nathalie Busschaert, Seong-Hyun Park, Kyung-Hwa Baek, Yoon Pyo Choi, Jinhong Park, Ethan N W Howe, Jennifer R Hiscock, Louise E Karagiannidis, Igor Marques, Vítor Félix, Wan Namkung, Jonathan L Sessler, Philip A Gale, Injae Shin
Perturbations in cellular chloride concentrations can affect cellular pH and autophagy and lead to the onset of apoptosis. With this in mind, synthetic ion transporters have been used to disturb cellular ion homeostasis and thereby induce cell death; however, it is not clear whether synthetic ion transporters can also be used to disrupt autophagy. Here, we show that squaramide-based ion transporters enhance the transport of chloride anions in liposomal models and promote sodium chloride influx into the cytosol...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644463/hypersensitive-dual-function-luminescence-switching-of-a-silver-chalcogenolate-cluster-based-metal-organic-framework
#14
Ren-Wu Huang, Yong-Sheng Wei, Xi-Yan Dong, Xiao-Hui Wu, Chen-Xia Du, Shuang-Quan Zang, Thomas C W Mak
Silver(i) chalcogenide/chalcogenolate clusters are promising photofunctional materials for sensing, optoelectronics and solar energy harvesting applications. However, their instability and poor room-temperature luminescent quantum yields have hampered more extensive study. Here, we graft such clusters to adaptable bridging ligands, enabling their interconnection and the formation of rigid metal-organic frameworks. By controlling the spatial separation and orientation of the clusters, they then exhibit enhanced stability (over one year) and quantum yield (12...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644484/erratum-tuning-underwater-adhesion-with-cation-%C3%AF-interactions
#15
Matthew A Gebbie, Wei Wei, Alex M Schrader, Thomas R Cristiani, Howard A Dobbs, Matthew Idso, Bradley F Chmelka, J Herbert Waite, Jacob N Israelachvili
No abstract text is available yet for this article.
June 23, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644479/enzymatic-catalysis-new-functional-twists-for-p450s
#16
Rudi Fasan
No abstract text is available yet for this article.
June 23, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644478/a-chemical-century
#17
EDITORIAL
(no author information available yet)
No abstract text is available yet for this article.
June 23, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644477/dna-nanotechnology-bringing-lipid-bilayers-into-shape
#18
Stefan Howorka
No abstract text is available yet for this article.
June 23, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644473/addendum-aldehydes-as-alkyl-carbanion-equivalents-for-additions-to-carbonyl-compounds
#19
Haining Wang, Xi-Jie Dai, Chao-Jun Li
No abstract text is available yet for this article.
June 23, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644472/placing-and-shaping-liposomes-with-reconfigurable-dna-nanocages
#20
Zhao Zhang, Yang Yang, Frederic Pincet, Marc C Llaguno, Chenxiang Lin
The diverse structure and regulated deformation of lipid bilayer membranes are among a cell's most fascinating features. Artificial membrane-bound vesicles, known as liposomes, are versatile tools for modelling biological membranes and delivering foreign objects to cells. To fully mimic the complexity of cell membranes and optimize the efficiency of delivery vesicles, controlling liposome shape (both statically and dynamically) is of utmost importance. Here we report the assembly, arrangement and remodelling of liposomes with designer geometry: all of which are exquisitely controlled by a set of modular, reconfigurable DNA nanocages...
June 23, 2017: Nature Chemistry
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