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Nature Chemistry

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https://www.readbyqxmd.com/read/28221361/dynamic-control-of-chirality-and-self-assembly-of-double-stranded-helicates-with-light
#1
Depeng Zhao, Thomas van Leeuwen, Jinling Cheng, Ben L Feringa
Helicity switching in biological and artificial systems is a fundamental process that allows for the dynamic control of structures and their functions. In contrast to chemical approaches to responsive behaviour in helicates, the use of light as an external stimulus offers unique opportunities to invert the chirality of helical structures in a non-invasive manner with high spatiotemporal precision. Here, we report that unidirectional rotary motors with connecting oligobipyridyl ligands, which can dynamically change their chirality upon irradiation, assemble into metal helicates that are responsive to light...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221360/why-copper-is-preferred-over-iron-for-oxygen-activation-and-reduction-in-haem-copper-oxidases
#2
Ambika Bhagi-Damodaran, Matthew A Michael, Qianhong Zhu, Julian Reed, Braddock A Sandoval, Evan N Mirts, Saumen Chakraborty, Pierre Moënne-Loccoz, Yong Zhang, Yi Lu
Haem-copper oxidase (HCO) catalyses the natural reduction of oxygen to water using a haem-copper centre. Despite decades of research on HCOs, the role of non-haem metal and the reason for nature's choice of copper over other metals such as iron remains unclear. Here, we use a biosynthetic model of HCO in myoglobin that selectively binds different non-haem metals to demonstrate 30-fold and 11-fold enhancements in the oxidase activity of Cu- and Fe-bound HCO mimics, respectively, as compared with Zn-bound mimics...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221358/ionic-solutions-of-two-dimensional-materials
#3
Patrick L Cullen, Kathleen M Cox, Mohammed K Bin Subhan, Loren Picco, Oliver D Payton, David J Buckley, Thomas S Miller, Stephen A Hodge, Neal T Skipper, Vasiliki Tileli, Christopher A Howard
Strategies for forming liquid dispersions of nanomaterials typically focus on retarding reaggregation, for example via surface modification, as opposed to promoting the thermodynamically driven dissolution common for molecule-sized species. Here we demonstrate the true dissolution of a wide range of important 2D nanomaterials by forming layered material salts that spontaneously dissolve in polar solvents yielding ionic solutions. The benign dissolution advantageously maintains the morphology of the starting material, is stable against reaggregation and can achieve solutions containing exclusively individualized monolayers...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221357/direct-assembly-of-multiply-oxygenated-carbon-chains-by-decarbonylative-radical-radical-coupling-reactions
#4
Kengo Masuda, Masanori Nagatomo, Masayuki Inoue
Pentoses and hexoses contain more than three oxygen-bearing stereocentres and are ideal starting materials for the synthesis of multiply oxygenated natural products such as sagittamide D, maitotoxin and hikizimycin. Here we demonstrate new radical-radical homocoupling reactions of sugar derivatives with minimal perturbation of their chiral centres. The radical exchange procedure using Et3B/O2 converted sugar-derived α-alkoxyacyl tellurides into α-alkoxy radicals via decarbonylation and rapidly dimerized the monomeric radicals...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221356/terahertz-echoes-reveal-the-inhomogeneity-of-aqueous-salt-solutions
#5
Andrey Shalit, Saima Ahmed, Janne Savolainen, Peter Hamm
The structural and dynamical properties of water are known to be affected by ion solvation. However, a consistent molecular picture that describes how and to what extent ions perturb the water structure is still missing. Here we apply 2D Raman-terahertz spectroscopy to investigate the impact of monatomic cations on the relaxation dynamics of the hydrogen-bond network in aqueous salt solutions. The inherent ability of multidimensional spectroscopy to deconvolute heterogeneous relaxation dynamics is used to reveal the correlation between the inhomogeneity of the collective intermolecular hydrogen-bond modes and the viscosity of a salt solution...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221353/from-helical-to-planar-chirality-by-on-surface-chemistry
#6
Oleksandr Stetsovych, Martin Švec, Jaroslav Vacek, Jana Vacek Chocholoušová, Andrej Jančařík, Jiří Rybáček, Krzysztof Kosmider, Irena G Stará, Pavel Jelínek, Ivo Starý
The chirality of molecular structures is paramount in many phenomena, including enantioselective reactions, molecular self-assembly, biological processes and light or electron-spin polarization. Flat prochiral molecules, which are achiral in the gas phase or solution, can exhibit adsorption-induced chirality when deposited on surfaces. The whole array of such molecular adsorbates is naturally racemic as spontaneous global mirror-symmetry breaking is disfavoured. Here we demonstrate a chemical method of obtaining flat prochiral molecules adsorbed on the solid achiral surface in such a way that a specific adsorbate handedness globally dominates...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221352/dynamic-undocking-and-the-quasi-bound-state-as-tools-for-drug-discovery
#7
Sergio Ruiz-Carmona, Peter Schmidtke, F Javier Luque, Lisa Baker, Natalia Matassova, Ben Davis, Stephen Roughley, James Murray, Rod Hubbard, Xavier Barril
There is a pressing need for new technologies that improve the efficacy and efficiency of drug discovery. Structure-based methods have contributed towards this goal but they focus on predicting the binding affinity of protein-ligand complexes, which is notoriously difficult. We adopt an alternative approach that evaluates structural, rather than thermodynamic, stability. As bioactive molecules present a static binding mode, we devised dynamic undocking (DUck), a fast computational method to calculate the work necessary to reach a quasi-bound state at which the ligand has just broken the most important native contact with the receptor...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221351/imaging-quantum-stereodynamics-through-fraunhofer-scattering-of-no-radicals-with-rare-gas-atoms
#8
Jolijn Onvlee, Sean D S Gordon, Sjoerd N Vogels, Thomas Auth, Tijs Karman, Bethan Nichols, Ad van der Avoird, Gerrit C Groenenboom, Mark Brouard, Sebastiaan Y T van de Meerakker
Stereodynamics describes how the vector properties of molecules, such as the directions in which they move and the axes about which they rotate, affect the probabilities (or cross-sections) of specific processes or transitions that occur on collision. The main aspects of stereodynamics in inelastic atom-molecule collisions can often be understood from classical considerations, in which the particles are represented by billiard-ball-like hard objects. In a quantum picture, however, the collision is described in terms of matter waves, which can also scatter into the region of the geometrical shadow of the object and reveal detailed information on the pure quantum-mechanical contribution to the stereodynamics...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221349/surface-chemistry-single-handedness-in-flatland
#9
Karl-Heinz Ernst
No abstract text is available yet for this article.
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221348/self-assembly-of-nanoparticles-into-biomimetic-capsid-like-nanoshells
#10
Ming Yang, Henry Chan, Gongpu Zhao, Joong Hwan Bahng, Peijun Zhang, Petr Král, Nicholas A Kotov
Nanoscale compartments are one of the foundational elements of living systems. Capsids, carboxysomes, exosomes, vacuoles and other nanoshells easily self-assemble from biomolecules such as lipids or proteins, but not from inorganic nanomaterials because of difficulties with the replication of spherical tiling. Here we show that stabilizer-free polydispersed inorganic nanoparticles (NPs) can spontaneously organize into porous nanoshells. The association of water-soluble CdS NPs into self-limited spherical capsules is the result of scale-modified electrostatic, dispersion and other colloidal forces...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221346/synthesis-of-ent-be-43547a1-reveals-a-potent-hypoxia-selective-anticancer-agent-and-uncovers-the-biosynthetic-origin-of-the-apd-cld-natural-products
#11
Nikolaj L Villadsen, Kristian M Jacobsen, Ulrik B Keiding, Esben T Weibel, Bjørn Christiansen, Thomas Vosegaard, Morten Bjerring, Frank Jensen, Mogens Johannsen, Thomas Tørring, Thomas B Poulsen
Tumour hypoxia is speculated to be a key driver of therapeutic resistance and metastatic dissemination. Consequently, the discovery of new potent agents that selectively target the hypoxic cell population may reveal new and untapped antitumour mechanisms. Here we demonstrate that the BE-43547 subclass of the APD-CLD (amidopentadienoate-containing cyclolipodepsipeptides) natural products possesses highly hypoxia-selective growth-inhibitory activity against pancreatic cancer cells. To enable this discovery, we have developed the first synthesis of the BE-43547-macrocyclic scaffold in 16 steps (longest linear sequence), which also allowed access to the full panel of relative stereoisomers and ultimately to the assignment of stereochemical configuration...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221345/rational-design-of-reversible-fluorescent-probes-for-live-cell-imaging-and-quantification-of-fast-glutathione-dynamics
#12
Keitaro Umezawa, Masafumi Yoshida, Mako Kamiya, Tatsuya Yamasoba, Yasuteru Urano
Alterations in glutathione (GSH) homeostasis are associated with a variety of diseases and cellular functions, and therefore, real-time live-cell imaging and quantification of GSH dynamics are important for understanding pathophysiological processes. However, existing fluorescent probes are unsuitable for these purposes due to their irreversible fluorogenic mechanisms or slow reaction rates. In this work, we have successfully overcome these problems by establishing a design strategy inspired by Mayr's work on nucleophilic reaction kinetics...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221344/chemoproteomic-profiling-and-discovery-of-protein-electrophiles-in-human-cells
#13
Megan L Matthews, Lin He, Benjamin D Horning, Erika J Olson, Bruno E Correia, John R Yates, Philip E Dawson, Benjamin F Cravatt
Activity-based protein profiling (ABPP) serves as a chemical proteomic platform to discover and characterize functional amino acids in proteins on the basis of their enhanced reactivity towards small-molecule probes. This approach, to date, has mainly targeted nucleophilic functional groups, such as the side chains of serine and cysteine, using electrophilic probes. Here we show that 'reverse-polarity' (RP)-ABPP using clickable, nucleophilic hydrazine probes can capture and identify protein-bound electrophiles in cells...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221359/organic-chemistry-a-radical-step-forward
#14
Wenhao Zhang, Ang Li
No abstract text is available yet for this article.
February 21, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221355/corrigendum-intermediate-tunnelling-hopping-regime-in-dna-charge-transport
#15
Limin Xiang, Julio L Palma, Christopher Bruot, Vladimiro Mujica, Mark A Ratner, Nongjian Tao
No abstract text is available yet for this article.
February 21, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221354/energy-transfer-resonance-is-the-key-for-coherence
#16
Daniel B Turner
No abstract text is available yet for this article.
February 21, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221350/controlling-quantum-beating-signals-in-2d-electronic-spectra-by-packing-synthetic-heterodimers-on-single-walled-carbon-nanotubes
#17
Lili Wang, Graham B Griffin, Alice Zhang, Feng Zhai, Nicholas E Williams, Richard F Jordan, Gregory S Engel
In multidimensional spectroscopy, dynamics of coherences between excited states report on the interactions between electronic states and their environment. The prolonged coherence lifetimes revealed through beating signals in the spectra of some systems may result from vibronic coupling between nearly degenerate excited states, and recent observations confirm the existence of such coupling in both model systems and photosynthetic complexes. Understanding the origin of beating signals in the spectra of photosynthetic complexes has been given considerable attention; however, strategies to generate them in artificial systems that would allow us to test the hypotheses in detail are still lacking...
February 21, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28221347/the-unveiled-states-of-americium
#18
Ben Still
No abstract text is available yet for this article.
February 21, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/27995927/mechanism-of-o2-diffusion-and-reduction-in-fefe-hydrogenases
#19
Adam Kubas, Christophe Orain, David De Sancho, Laure Saujet, Matteo Sensi, Charles Gauquelin, Isabelle Meynial-Salles, Philippe Soucaille, Hervé Bottin, Carole Baffert, Vincent Fourmond, Robert B Best, Jochen Blumberger, Christophe Léger
FeFe hydrogenases are the most efficient H2-producing enzymes. However, inactivation by O2 remains an obstacle that prevents them being used in many biotechnological devices. Here, we combine electrochemistry, site-directed mutagenesis, molecular dynamics and quantum chemical calculations to uncover the molecular mechanism of O2 diffusion within the enzyme and its reactions at the active site. We propose that the partial reversibility of the reaction with O2 results from the four-electron reduction of O2 to water...
January 2017: Nature Chemistry
https://www.readbyqxmd.com/read/27995926/suppression-of-kasha-s-rule-as-a-mechanism-for-fluorescent-molecular-rotors-and-aggregation-induced-emission
#20
Hai Qian, Morgan E Cousins, Erik H Horak, Audrey Wakefield, Matthew D Liptak, Ivan Aprahamian
Although there are some proposed explanations for aggregation-induced emission, a phenomenon with applications that range from biosensors to organic light-emitting diodes, current understanding of the quantum-mechanical origin of this photophysical behaviour is limited. To address this issue, we assessed the emission properties of a series of BF2-hydrazone-based dyes as a function of solvent viscosity. These molecules turned out to be highly efficient fluorescent molecular rotors. This property, in addition to them being aggregation-induced emission luminogens, enabled us to probe deeper into their emission mechanism...
January 2017: Nature Chemistry
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