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ACS Central Science

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https://read.qxmd.com/read/30693338/two-tryptophans-are-better-than-one-in-accelerating-electron-flow-through-a-protein
#1
Kana Takematsu, Heather R Williamson, Pavle Nikolovski, Jens T Kaiser, Yuling Sheng, Petr Pospíšil, Michael Towrie, Jan Heyda, Daniel Hollas, Stanislav Záliš, Harry B Gray, Antonín Vlček, Jay R Winkler
We have constructed and structurally characterized a Pseudomonas aeruginosa azurin mutant Re126WWCuI , where two adjacent tryptophan residues (W124 and W122, indole separation 3.6-4.1 Å) are inserted between the CuI center and a Re photosensitizer coordinated to the imidazole of H126 (ReI (H126)(CO)3 (4,7-dimethyl-1,10-phenanthroline)+ ). CuI oxidation by the photoexcited Re label (*Re) 22.9 Å away proceeds with a ∼70 ns time constant, similar to that of a single-tryptophan mutant (∼40 ns) with a 19.4 Å Re-Cu distance...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693337/the-importance-of-salt-enhanced-electrostatic-repulsion-in-colloidal-crystal-engineering-with-dna
#2
Soyoung E Seo, Martin Girard, Monica Olvera de la Cruz, Chad A Mirkin
Realizing functional colloidal single crystals requires precise control over nanoparticles in three dimensions across multiple size regimes. In this regard, colloidal crystallization with programmable atom equivalents (PAEs) composed of DNA-modified nanoparticles allows one to program in a sequence-specific manner crystal symmetry, lattice parameter, and, in certain cases, crystal habit. Here, we explore how salt and the electrostatic properties of DNA regulate the attachment kinetics between PAEs. Counterintuitively, simulations and theory show that at high salt concentrations (1 M NaCl), the energy barrier for crystal growth increases by over an order of magnitude compared to low concentration (0...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693336/general-immobilization-of-ultrafine-alloyed-nanoparticles-within-metal-organic-frameworks-with-high-loadings-for-advanced-synergetic-catalysis
#3
Fengfeng Chen, Kui Shen, Junying Chen, Xianfeng Yang, Jie Cui, Yingwei Li
The development of a general synthesis approach for creating fine alloyed nanoparticles (NPs) in the pores of metal-organic frameworks (MOFs) shows great promise for advanced synergetic catalysis but has not been realized so far. Herein, for the first time we proposed a facile and general strategy to immobilize ultrafine alloyed NPs within the pores of an MOF by the galvanic replacement of transition-metal NPs (e.g., Cu, Co, and Ni) with noble-metal ions (e.g., Pd, Ru, and Pt) under high-intensity ultrasound irradiation...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693335/quantum-chemistry-on-quantum-computers-a-method-for-preparation-of-multiconfigurational-wave-functions-on-quantum-computers-without-performing-post-hartree-fock-calculations
#4
Kenji Sugisaki, Shigeaki Nakazawa, Kazuo Toyota, Kazunobu Sato, Daisuke Shiomi, Takeji Takui
The full configuration interaction (full-CI) method is capable of providing the numerically best wave functions and energies of atoms and molecules within basis sets being used, although it is intractable for classical computers. Quantum computers can perform full-CI calculations in polynomial time against the system size by adopting a quantum phase estimation algorithm (QPEA). In the QPEA, the preparation of initial guess wave functions having sufficiently large overlap with the exact wave function is recommended...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693334/a-selective-and-cell-permeable-mitochondrial-calcium-uniporter-mcu-inhibitor-preserves-mitochondrial-bioenergetics-after-hypoxia-reoxygenation-injury
#5
Joshua J Woods, Neeharika Nemani, Santhanam Shanmughapriya, Akshay Kumar, MengQi Zhang, Sarah R Nathan, Manfred Thomas, Edmund Carvalho, Karthik Ramachandran, Subramanya Srikantan, Peter B Stathopulos, Justin J Wilson, Muniswamy Madesh
Mitochondrial Ca2+ (m Ca2+ ) uptake mediated by the mitochondrial calcium uniporter (MCU) plays a critical role in signal transduction, bioenergetics, and cell death, and its dysregulation is linked to several human diseases. In this study, we report a new ruthenium complex Ru265 that is cell-permeable, minimally toxic, and highly potent with respect to MCU inhibition. Cells treated with Ru265 show inhibited MCU activity without any effect on cytosolic Ca2+ dynamics and mitochondrial membrane potential (ΔΨm )...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693333/bioorthogonal-engineering-of-bacterial-effectors-for-spatial-temporal-modulation-of-cell-signaling
#6
Jingyi Zhao, Yanjun Liu, Feng Lin, Weixia Wang, Shaojun Yang, Yun Ge, Peng R Chen
The complicated and entangled cell signaling network is dynamically regulated by a wide array of enzymes such as kinases. It remains desirable but challenging to specifically modulate individual, endogenous kinases within a cell, particularly in a spatial-temporally controlled fashion. Current strategies toward regulating the intracellular functions of a kinase of interest either lack specificity or require genetic engineering that may perturb its physiological activity. Herein, we harnessed a bacterial effector OspF for optical and chemical modulation of the endogenous mitogen-activated protein kinase (MAPK) cascade in living cells and mice...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693332/high-performance-concurrent-chemo-immuno-radiotherapy-for-the-treatment-of-hematologic-cancer-through-selective-high-affinity-ligand-antibody-mimic-functionalized-doxorubicin-encapsulated-nanoparticles
#7
Kin Man Au, Rod Balhorn, Monique C Balhorn, Steven I Park, Andrew Z Wang
Non-Hodgkin lymphoma is one of the most common types of cancer. Relapsed and refractory diseases are still common and remain significant challenges as the majority of these patients eventually succumb to the disease. Herein, we report a translatable concurrent chemo-immuno-radiotherapy (CIRT) strategy that utilizes fully synthetic antibody mimic Selective High-Affinity Ligand (SHAL)-functionalized doxorubicin-encapsulated nanoparticles (Dox NPs) for the treatment of human leukocyte antigen-D related (HLA-DR) antigen-overexpressed tumors...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693331/high-performance-n-2-to-nh-3-conversion-electrocatalyzed-by-mo-2-c-nanorod
#8
Xiang Ren, Jinxiu Zhao, Qin Wei, Yongjun Ma, Haoran Guo, Qian Liu, Yuan Wang, Guanwei Cui, Abdullah M Asiri, Baihai Li, Bo Tang, Xuping Sun
The synthesis of NH3 is mainly dominated by the traditional energy-consuming Haber-Bosch process with a mass of CO2 emission. Electrochemical conversion of N2 to NH3 emerges as a carbon-free process for the sustainable artificial N2 reduction reaction (NRR), but requires an efficient and stable electrocatalyst. Here, we report that the Mo2 C nanorod serves as an excellent NRR electrocatalyst for artificial N2 fixation to NH3 with strong durability and acceptable selectivity under ambient conditions. Such a catalyst shows a high Faradaic efficiency of 8...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693330/a-laser-driven-flow-chemistry-platform-for-scaling-photochemical-reactions-with-visible-light
#9
Kaid C Harper, Eric G Moschetta, Shailendra V Bordawekar, Steven J Wittenberger
Visible-light-promoted organic reactions can offer increased reactivity and selectivity via unique reaction pathways to address a multitude of practical synthetic problems, yet few practical solutions exist to employ these reactions for multikilogram production. We have developed a simple and versatile continuous stirred tank reactor (CSTR) equipped with a high-intensity laser to drive photochemical reactions at unprecedented rates in continuous flow, achieving kg/day throughput using a 100 mL reactor. Our approach to flow reactor design uses the Beer-Lambert law as a guideline to optimize catalyst concentration and reactor depth for maximum throughput...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693329/principles-of-inter-amino-acid-recognition-revealed-by-binding-energies-between-homogeneous-oligopeptides
#10
Huiwen Du, Xiaoyu Hu, Hongyang Duan, Lanlan Yu, Fuyang Qu, Qunxing Huang, Wangshu Zheng, Hanyi Xie, Jiaxi Peng, Rui Tuo, Dan Yu, Yuchen Lin, Wenzhe Li, Yongfang Zheng, Xiaocui Fang, Yimin Zou, Huayi Wang, Mengting Wang, Paul S Weiss, Yanlian Yang, Chen Wang
We have determined the interaction strengths of the common naturally occurring amino acids using a complete binding affinity matrix of 20 × 20 pairs of homo-octapeptides consisting of the 20 common amino acids between stationary and mobile states. We used a bead-based fluorescence assay for these measurements. The results provide a basis for analyzing specificity, polymorphisms, and selectivity of inter-amino-acid interactions. Comparative analyses of the binding energies, i.e., the free energies of association (Δ G A ), reveal contributions assignable to both main-chain-related and side-chain-related interactions originating from the chemical structures of these 20 common amino acids...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693328/a-telescoping-view-of-solute-architectures-in-a-complex-fluid-system
#11
Ryuhei Motokawa, Tohru Kobayashi, Hitoshi Endo, Junju Mu, Christopher D Williams, Andrew J Masters, Mark R Antonio, William T Heller, Michihiro Nagao
Short- and long-range correlations between solutes in solvents can influence the macroscopic chemistry and physical properties of solutions in ways that are not fully understood. The class of liquids known as complex (structured) fluids-containing multiscale aggregates resulting from weak self-assembly-are especially important in energy-relevant systems employed for a variety of chemical- and biological-based purification, separation, and catalytic processes. In these, solute (mass) transfer across liquid-liquid (water, oil) phase boundaries is the core function...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693327/a-novel-1-4-%C3%AE-linked-glucoxylan-is-synthesized-by-members-of-the-cellulose-synthase-like-f-gene-family-in-land-plants
#12
Alan Little, Jelle Lahnstein, David W Jeffery, Shi F Khor, Julian G Schwerdt, Neil J Shirley, Michelle Hooi, Xiaohui Xing, Rachel A Burton, Vincent Bulone
As a significant component of monocot cell walls, (1,3;1,4)-β-glucan has conclusively been shown to be synthesized by the cellulose synthase-like F6 protein. In this study, we investigated the synthetic activity of other members of the barley ( Hordeum vulgare ) CslF gene family using heterologous expression. As expected, the majority of the genes encode proteins that are capable of synthesizing detectable levels of (1,3;1,4)-β-glucan. However, overexpression of HvCslF3 and HvCslF10 genes resulted in the synthesis of a novel linear glucoxylan that consists of (1,4)-β-linked glucose and xylose residues...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693326/effective-distance-for-dna-mediated-charge-transport-between-repair-proteins
#13
Edmund C M Tse, Theodore J Zwang, Sebastian Bedoya, Jacqueline K Barton
The stacked aromatic base pairs within the DNA double helix facilitate charge transport down its length in the absence of lesions, mismatches, and other stacking perturbations. DNA repair proteins containing [4Fe4S] clusters can take advantage of DNA charge transport (CT) chemistry to scan the genome for mistakes more efficiently. Here we examine the effective length over which charge can be transported along DNA between these repair proteins. We define the effective CT distance as the length of DNA within which two proteins are able to influence their ensemble affinity to the DNA duplex via CT...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693325/transferable-machine-learning-model-of-the-electron-density
#14
Andrea Grisafi, Alberto Fabrizio, Benjamin Meyer, David M Wilkins, Clemence Corminboeuf, Michele Ceriotti
The electronic charge density plays a central role in determining the behavior of matter at the atomic scale, but its computational evaluation requires demanding electronic-structure calculations. We introduce an atom-centered, symmetry-adapted framework to machine-learn the valence charge density based on a small number of reference calculations. The model is highly transferable, meaning it can be trained on electronic-structure data of small molecules and used to predict the charge density of larger compounds with low, linear-scaling cost...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693324/lipid-dependent-alternating-access-mechanism-of-a-bacterial-multidrug-abc-exporter
#15
Kalyan Immadisetty, Jeevapani Hettige, Mahmoud Moradi
By undergoing conformational changes, active membrane transporters alternate between an inward-facing (IF) and an outward-facing (OF) state to transport their substrates across cellular membrane. The conformational landscape of membrane transporters, however, could be influenced by their environment, and the dependence of the alternating access mechanism on the lipid composition has not been understood at the molecular level. We have performed an extensive set of microsecond-level all-atom molecular dynamics (MD) simulations on bacterial ATP binding cassette (ABC) exporter Sav1866 in six different phosphocholine (PC) and phosphoethanolamine (PE) lipid membrane environments...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693323/energy-transfer-editing-in-lanthanide-activated-upconversion-nanocrystals-a-toolbox-for-emerging-applications
#16
REVIEW
Xian Qin, Jiahui Xu, Yiming Wu, Xiaogang Liu
Advanced nanoscale synthetic techniques provide a versatile platform for programmable control over the size, morphology, and composition of nanocrystals doped with lanthanide ions. Characteristic upconversion luminescence features originating from the 4f-4f optical transitions of lanthanides can be achieved through predesigned energy transfer pathways, enabling wide applications ranging from ultrasensitive biological detection to advanced spectroscopic instrumentation with high spatiotemporal resolution. Here, we review recent scientific and technological discoveries that have prompted the realization of these peculiar functions of lanthanide-doped upconversion nanocrystals and discuss the mechanistic studies of energy transfer involved in upconversion processes...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693322/heme-and-nonheme-high-valent-iron-and-manganese-oxo-cores-in-biological-and-abiological-oxidation-reactions
#17
REVIEW
Mian Guo, Teresa Corona, Kallol Ray, Wonwoo Nam
Utilization of O2 as an abundant and environmentally benign oxidant is of great interest in the design of bioinspired synthetic catalytic oxidation systems. Metalloenzymes activate O2 by employing earth-abundant metals and exhibit diverse reactivities in oxidation reactions, including epoxidation of olefins, functionalization of alkane C-H bonds, arene hydroxylation, and syn -dihydroxylation of arenes. Metal-oxo species are proposed as reactive intermediates in these reactions. A number of biomimetic metal-oxo complexes have been synthesized in recent years by activating O2 or using artificial oxidants at iron and manganese centers supported on heme or nonheme-type ligand environments...
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693321/amphiphile-based-complex-fluids-the-self-assembly-ensemble-as-protagonist
#18
Aurora E Clark
No abstract text is available yet for this article.
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693320/charge-transport-communication-through-dna-by-protein-fe-s-clusters-how-far-is-not-too-far
#19
Aleem Syed, John A Tainer
No abstract text is available yet for this article.
January 23, 2019: ACS Central Science
https://read.qxmd.com/read/30693319/tackling-delhi-s-air-pollution-problem
#20
Prachi Patel
No abstract text is available yet for this article.
January 23, 2019: ACS Central Science
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