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crystal structure transporter

Kai Wang, Xiaoguang Xu, Liying Lu, Haicheng Wang, Yan Li, Yong Wu, Jun Miao, Jin Z Zhang, Yong Jiang
Ag/Bi2 Fe4 O9 nanoparticles (BFO NPs) have been synthesized using a two step approach involving glycine combustion and visible light irradiation. Their structures were characterized in detail using XRD, TEM, SEM, and STEM techniques. Their electrocatalytic properties were studied through enzymatic glucose detection with an amperometric biosensor. The Ag deposited on selective crystal facets of BFO NPs significantly enhanced their electrocatalytic activity. To gain insight into the origin of the enhanced electrocatalytic activities, we have carried out studies of Ag+ reduction and Mn2+ oxidation reaction at {200} and {001} facets, respectively...
March 22, 2018: ACS Applied Materials & Interfaces
Bhupinder Sandhu, Abhijeet S Sinha, John Desper, Christer B Aakeröy
The solid-form landscape of urea was explored using full interaction maps (FIMs) and data from the CSD to develop optimum protocols for synthesizing co-crystals of urea. As a result, 49 of the 60 attempted reactions produced new co-crystals, and the crystal structures of four of these are presented. Moreover, the goal of reducing the solubility and lowering the hygroscopicity of the parent compound was achieved, which in turn offers new opportunities for application as a slow-release fertilizer with limited hygroscopicity, thereby reducing many current problems of transport, handling, and storage of urea...
March 22, 2018: Chemical Communications: Chem Comm
Wolfgang Buckel, Rudolf K Thauer
There are two types of electron bifurcation (EB), either quinone- or flavin-based (QBEB/FBEB), that involve reduction of a quinone or flavin by a two-electron transfer and two reoxidations by a high- and low-potential one-electron acceptor with a reactive semiquinone intermediate. In QBEB, the reduced low-potential acceptor (cytochrome b) is exclusively used to generate ΔμH+ . In FBEB, the "energy-rich" low-potential reduced ferredoxin or flavodoxin has dual function. It can give rise to ΔμH+ /Na+ via a ferredoxin:NAD reductase (Rnf) or ferredoxin:proton reductase (Ech) or conducts difficult reductions such as CO2 to CO...
March 21, 2018: Chemical Reviews
Sean D Workman, Liam J Worrall, Natalie C J Strynadka
Undecaprenyl pyrophosphate phosphatase (UppP) is an integral membrane protein that recycles the lipid carrier essential to the ongoing biosynthesis of the bacterial cell wall. Individual building blocks of peptidoglycan are assembled in the cytoplasm on undecaprenyl phosphate (C55-P) before being flipped to the periplasmic face, where they are polymerized and transferred to the existing cell wall sacculus, resulting in the side product undecaprenyl pyrophosphate (C55-PP). Interruption of UppP's regeneration of C55-P from C55-PP leads to the buildup of cell wall intermediates and cell lysis...
March 20, 2018: Nature Communications
Alexandre Luscher, Lucile Moynié, Pamela Saint Auguste, Dirk Bumann, Lena Mazza, Daniel Pletzer, James H Naismith, Thilo Köhler
The conjugation of siderophores to antimicrobial molecules is an attractive strategy to overcome the low outer membrane permeability of Gram-negative bacteria. In this Trojan horse approach the transport of drug conjugates is redirected via TonB-dependent receptors (TBDR), involved in the uptake of essential nutrients including iron. Previous reports have demonstrated the involvement of the TBDRs PiuA and PirA from Pseudomonas aeruginosa and their orthologues in Acinetobacter baumannii in the uptake of siderophore-beta-lactam drug conjugates...
March 19, 2018: Antimicrobial Agents and Chemotherapy
Khushbu Shah, Sudhir Raghavan, Zhanjun Hou, Larry H Matherly, Aleem Gangjee
All clinically used antifolates lack transport selectivity for tumors over normal cells resulting in dose-limiting toxicities. There is growing interest in developing novel tumor-targeted cytotoxic antifolates with selective transport into tumors over normal cells via the proton-coupled folate transporter (PCFT) over the ubiquitously expressed reduced folate carrier (RFC). A lack of X-ray crystal structures or predictive models for PCFT or RFC has hindered structure-aided drug design for PCFT-selective therapeutics...
February 20, 2018: Journal of Molecular Graphics & Modelling
Sebastian Hiller, Björn M Burmann
Living cells contain molecular chaperones that are organized in intricate networks to surveil protein homeostasis by avoiding polypeptide misfolding, aggregation, and the generation of toxic species. In addition, cellular chaperones also fulfill a multitude of alternative functionalities: transport of clients towards a target location, help them fold, unfold misfolded species, resolve aggregates, or deliver clients towards proteolysis machineries. Until recently, the only available source of atomic resolution information for virtually all chaperones were crystal structures of their client-free, apo-forms...
April 2018: Journal of Magnetic Resonance
Meriem El Ghachi, Nicole Howe, Chia-Ying Huang, Vincent Olieric, Rangana Warshamanage, Thierry Touzé, Dietmar Weichert, Phillip J Stansfeld, Meitian Wang, Fred Kerff, Martin Caffrey
As a protective envelope surrounding the bacterial cell, the peptidoglycan sacculus is a site of vulnerability and an antibiotic target. Peptidoglycan components, assembled in the cytoplasm, are shuttled across the membrane in a cycle that uses undecaprenyl-phosphate. A product of peptidoglycan synthesis, undecaprenyl-pyrophosphate, is converted to undecaprenyl-phosphate for reuse in the cycle by the membrane integral pyrophosphatase, BacA. To understand how BacA functions, we determine its crystal structure at 2...
March 14, 2018: Nature Communications
Thao P Nguyen, P Roy, Ji Hoon Shim
The relationship between structure and charge transport properties of phenacene organic semiconductors has been studied with focus on [6] → [10]phenacene. Upon inserting phenyl rings, the π-extended structure results in strong electronic coupling interactions and reduction of reorganization energy. Using the classical Marcus charge transport theory, we predict that hole mobility in the phenacene series increases gradually up to 8.0 cm2 V-1 s-1 at [10]phenacene. This is remarkably high among other discovered OSCs, surpassing that of pentacene...
March 14, 2018: Physical Chemistry Chemical Physics: PCCP
Selma Sassi, Christophe Candolfi, Christine Gendarme, Anne Dauscher, Bertrand Lenoir
The crystal structure and transport properties (2-723 K) of the homologous compound Pb5 Bi6 Se14 with partial substitution of Te for Se are studied by means of powder X-ray diffraction, scanning electron microscopy, electrical resistivity, thermopower, thermal conductivity and Hall effect measurements. Polycrystalline samples of Pb5 Bi6 Se14-x Tex (0 ≤ x ≤ 1.0) were prepared by a two-step synthesis method based on the pseudo-binary PbSe-Bi2 Se3 phase diagram combined with Te substitution in the PbSe precursor...
March 14, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Takashi Kato, Junya Uchida, Takahiro Ichikawa, Takeshi Sakamoto
Since the discovery of the liquid-crystalline state in 1888, liquid crystal science has made great advances through fusion with various technologies and disciplines. Recently, new molecular design strategies and new self-assembled structures have been developed as a result of the progress made in synthetic procedures and characterization techniques. Since these liquid crystals exhibit new functions and properties derived from their nanostructures and alignment, a variety of new functions for liquid crystals, such as transport for energy applications, separation for environmental applications, chromism, sensing, electrooptical effects, actuation, and templating have been proposed...
March 13, 2018: Angewandte Chemie
Cyril Hamiaux, Revel S M Drummond, Zhiwei Luo, Hui Wen Lee, Prachi Sharma, Bart J Janssen, Nigel B Perry, William A Denny, Kimberley C Snowden
The strigolactone (SL) family of plant hormones regulates a broad range of physiological processes affecting plant growth and development and also plays essential roles in controlling interactions with parasitic weeds and symbiotic fungi. Recent progress elucidating details of SL biosynthesis, signalling, and transport offer many opportunities for discovering new plant growth regulators via chemical interference. Here, using high throughput screening and downstream biochemical assays, we identified N -phenylanthranilic acid derivatives as potent inhibitors of the SL receptors from petunia (DAD2), rice (OsD14) and Arabidopsis (AtD14)...
March 9, 2018: Journal of Biological Chemistry
Chen Wang, Qiyuan He, Udayabagya Halim, Yuanyue Liu, Enbo Zhu, Zhaoyang Lin, Hai Xiao, Xidong Duan, Ziying Feng, Rui Cheng, Nathan O Weiss, Guojun Ye, Yun-Chiao Huang, Hao Wu, Hung-Chieh Cheng, Imran Shakir, Lei Liao, Xianhui Chen, William A Goddard Iii, Yu Huang, Xiangfeng Duan
Artificial superlattices, based on van der Waals heterostructures of two-dimensional atomic crystals such as graphene or molybdenum disulfide, offer technological opportunities beyond the reach of existing materials. Typical strategies for creating such artificial superlattices rely on arduous layer-by-layer exfoliation and restacking, with limited yield and reproducibility. The bottom-up approach of using chemical-vapour deposition produces high-quality heterostructures but becomes increasingly difficult for high-order superlattices...
March 7, 2018: Nature
Manuel Weiss, Dominik A Weber, Anatoliy Senyshyn, Jürgen Janek, Wolfgang G Zeier
Li1+x Alx Ge2-x (PO4 )3 (LAGP) is a solid lithium ion conductor belonging to the NASICON family, representing the solid solution of LiGe2 (PO 4 )3 and AlPO4 . The typical syntheses of LAGP either involve high temperature melt-quenching, which is complicated and expensive, or a sol-gel process requiring costly organic germanium precursors. In this work, we report a simple method based on aqueous solutions without the need of ethoxide precursos. Using synchrotron and neutron diffraction, the crystal structure, the occupancies for Al and Ge, as well as the distribution of lithium were determined...
March 8, 2018: ACS Applied Materials & Interfaces
A Rahal, S Megdiche Borchani, K Guidara, M Megdiche
In this paper, we report the measurements of impedance spectroscopy for a new olivine-type lithium deficiency Li0.9 □0.1 NiV0.5 P0.5 O4 compound. It was synthesized by the conventional solid-state technique. All the X-ray diffraction peaks of the compound are indexed, and it is found that the sample is well crystallized in orthorhombic olivine structure belonging to the space group Pnma . Conductivity and dielectric analyses of the sample are carried out at different temperatures and frequencies using the complex impedance spectroscopy technique...
February 2018: Royal Society Open Science
Megan J Maher, Anuradha S Herath, Saumya R Udagedara, David A Dougan, Kaye N Truscott
Succinate:quinone oxidoreductase (SQR) functions in energy metabolism, coupling the tricarboxylic acid cycle and electron transport chain in bacteria and mitochondria. The biogenesis of flavinylated SdhA, the catalytic subunit of SQR, is assisted by a highly conserved assembly factor termed SdhE in bacteria via an unknown mechanism. By using X-ray crystallography, we have solved the structure of Escherichia coli SdhE in complex with SdhA to 2.15-Å resolution. Our structure shows that SdhE makes a direct interaction with the flavin adenine dinucleotide-linked residue His45 in SdhA and maintains the capping domain of SdhA in an "open" conformation...
March 7, 2018: Proceedings of the National Academy of Sciences of the United States of America
Lili Dong, Ruirui Feng, Jiawei Bi, Shengqiang Shen, Huizhe Lu, Jianjun Zhang
Human sodium-dependent glucose co-transporter 2 (hSGLT2) is a crucial therapeutic target in the treatment of type 2 diabetes. In this study, both comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were applied to generate three-dimensional quantitative structure-activity relationship (3D-QSAR) models. In the most accurate CoMFA-based and CoMSIA-based QSAR models, the cross-validated coefficients (r2 cv ) were 0.646 and 0.577, respectively, while the non-cross-validated coefficients (r2 ) were 0...
March 6, 2018: Journal of Molecular Modeling
Ida Hafstrand, Elien M Doorduijn, Renhua Sun, Anna Talyzina, Marjolein Sluijter, Sara Pellegrino, Tatyana Sandalova, Adil Doganay Duru, Thorbald van Hall, Adnane Achour
Human cancers frequently display defects in Ag processing and presentation allowing for immune evasion, and they therefore constitute a significant challenge for T cell-based immunotherapy. We have previously demonstrated that the antigenicity of tumor-associated Ags can be significantly enhanced through unconventional residue modifications as a novel tool for MHC class I (MHC-I)-based immunotherapy approaches. We have also previously identified a novel category of cancer neo-epitopes, that is, T cell epitopes associated with impaired peptide processing (TEIPP), that are selectively presented by MHC-I on cells lacking the peptide transporter TAP...
March 5, 2018: Journal of Immunology: Official Journal of the American Association of Immunologists
Yasuhiro Matsunaga, Tsutomu Yamane, Tohru Terada, Kei Moritsugu, Hiroshi Fujisaki, Satoshi Murakami, Mitsunori Ikeguchi, Akinori Kidera
The multidrug transporter AcrB transports a broad range of drugs out of the cell by means of the proton-motive force. The asymmetric crystal structure of trimeric AcrB suggests a functionally rotating mechanism for drug transport. Despite various supportive forms of evidence from biochemical and simulation studies for this mechanism, the link between the functional rotation and proton translocation across the membrane remains elusive. Here, calculating the minimum free energy pathway of the functional rotation for the complete AcrB trimer, we describe the structural and energetic basis behind the coupling between the functional rotation and the proton translocation at atomic resolution...
March 6, 2018: ELife
Yoshiki Mino
 The X-ray crystallographic analysis of the single-crystal mugineic acid-Cu(II) complex showed that mugineic acid acts as a hexadentate ligand. Mugineic acid, a typical phytosiderophore, shows a marked stimulating effect on59 Fe-uptake and chlorophyll synthesis in rice plants. A salient feature is the higher reduction potential of the mugineic acid-Fe(III) complex than those of bacterial siderophores. X-ray diffraction study of the structurally analogous Co(III) complex of the mugineic acid-Fe(III) complex demonstrates that the azetidine nitrogen and secondary amine nitrogen, and both terminal carboxylate oxygens, coordinate as basal planar donors, and the hydroxyl oxygen and intermediate carboxylate oxygen bind as axial donors in a nearly octahedral configuration...
2018: Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan
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