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Stefano Mangani, Cecilia Pozzi, Flavio Di Pisa, Filomena De Luca, Manuela Benvenuti, Jean-Denis Docquier
β-lactamases (BLs) are important antibiotic resistance determinants that significantly compromise the efficacy of valuable β-lactam antibacterial drugs. For that reason, combinations with β-lactamase inhibitor were developed. Avibactam is the first non-β-lactam BL inhibitor introduced in clinical practice. Ceftazidime-avibactam represents one of the few last-resort antibiotics available for the treatment of infections caused by near pandrug-resistant bacteria. TRU-1 is a chromosomally-encoded AmpC-type BL of Aeromonas enteropelogenes, related to the FOX-type BLs and constitutes a good model for class C BLs...
May 22, 2018: ChemMedChem
Seline Glorieux, Liselot Steen, Jos De Brabanter, Imogen Foubert, Ilse Fraeye
The aim of this research was to simultaneously study the effect of meat type (chicken breast and leg meat), animal fatty acid composition (selected pork backfats having a low and high degree of saturation, respectively), and isothermal temperature (50, 60, 70, and 80 °C) on the viscoelastic properties of meat batters during and after application of different time-temperature profiles. Gelation of meat proteins contributed most to the viscoelastic properties of meat batters during heating, whereas crystallization of the lipids especially contributed to the viscoelastic properties during the cooling phase...
May 22, 2018: Journal of Food Science
Dominik Naglav, Briac Tobey, Kevin Dzialkowski, Dieter Bläser, Christoph Wölper, Georg Jansen, Stephan Schulz
Spontaneous ion separation of the scorpionate beryllium complex, TpBeI 1 (Tp = 1-trispyrazolylborate), occurs upon treatment with THF, yielding [TpBe(thf)]I 2, which was characterized by heteronuclear NMR spectroscopy (1H, 9Be, 13C) and structurally characterized by single crystal X-ray diffraction. 2 represents a rare example of a structurally characterized monocationic beryllium complex, and to the best of our knowledge, the synthesis of 2 by a solvent-induced ion separation has previously only been observed in the reactions of beryllium dihalides with strong Lewis bases...
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Alexandra Hicken, Andrew J P White, Mark R Crimmin
The preparation and structural characterisation of three new heterobimetallic hydride complexes containing 3-centre,2-electron W-H-Cu bonds is reported. These complexes have been characterised by single crystal X-ray crystallography and multinuclear NMR spectroscopy. The bonding in these complexes has been analysed by DFT calculations.
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Xiao Wan, Yuan Yao, Lei Fang, Junjun Liu
Butyrylcholinesterase (BChE) has been actively involved in drug discoveries from many fields for decades. In the crystal structure of the BChE-tacrine complex, there is an unanticipated formyl-proline molecule resolved very close to tacrine, raising an essential question on how reliable it is to apply the binding pose in a crystal structure to analyze related experimental observations, in which no formyl-proline is actually involved. In this study, by performing a series of 100 ns molecular dynamics simulations, we demonstrate that it is safe to employ the structural information from this crystal structure to analyze related experimental observations...
May 22, 2018: Physical Chemistry Chemical Physics: PCCP
Chang Woo Lee, Sun-Ha Park, Sung Gu Lee, Hyun Ho Park, Hak Jun Kim, HaJeung Park, Hyun Park, Jun Hyuck Lee
Dihydrodipicolinate reductase (DHDPR) is a key enzyme in the diaminopimelate- and lysine-synthesis pathways that reduces DHDP to tetrahydrodipicolinate. Although DHDPR uses both NADPH and NADH as a cofactor, the structural basis for cofactor specificity and preference remains unclear. Here, we report that Paenisporosarcina sp. TG-14 PaDHDPR has a strong preference for NADPH over NADH, as determined by isothermal titration calorimetry and enzymatic activity assays. We determined the crystal structures of PaDHDPR alone, with its competitive inhibitor (dipicolinate), and the ternary complex of the enzyme with dipicolinate and NADPH, with results showing that only the ternary complex had a fully closed conformation and suggesting that binding of both substrate and nucleotide cofactor is required for enzymatic activity...
May 21, 2018: Scientific Reports
Vivek Kumar, Manfred Reehuis, Andreas Hoser, Peter Adler, Claudia Felser
We have investigated the crystal and magnetic structure of Mn<sub>2</sub>PtPd alloy using powder X-ray and neutron diffraction experiments. This compound is believed to belong to the Heusler family having crystal symmetry I4/mmm (TiAl<sub>3</sub>-type). However, in this work we found that the Pd and Pt atoms are disordered and thus Mn<sub>2</sub>PtPd crystallizes in the L1<sub>0</sub> structure having P4/mmm symmetry (CuAu-I type) like MnPt and MnPd binary alloys...
May 22, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Yatao Zhang, Yijia Shen, Jingwei Hou, Yiming Zhang, Winny Fam, Jindun Liu, Thomas D Bennett, Vicki Chen
Block copolymer materials have been considered as promising candidates to fabricate gas separation membranes. This microphase separation affects the polymer chain packing density and molecular separation efficiency. Here we demonstrate a method to template microphase separation within a thin composite Pebax membrane, through the controllable self-assembly of one-dimensional halloysite nanotubes (HNTs) within the thin film via solution casting technique. Crystallisation of the polyamide component is induced at the HNT surface, guiding subsequent crystal growth around the tubular structure...
May 22, 2018: ACS Applied Materials & Interfaces
Xiao-Qin Wei, Qian Pi, Fu-Xing Shen, Dong Shao, Hai-Yan Wei, Xin-Yi Wang
By reaction of K4[MoIII(CN)7]·2H2O, Mn(ClO4)2·6H2O and bidentate chelating ligands, three new cyano-bridged compounds, namely Mn2(3-pypz)(H2O)(CH3CN)[Mo(CN)7] (1), Mn2(1-pypz)(H2O)(CH3CN)[Mo(CN)7] (2) and Mn2(pyim)(H2O)(CH3CN)[Mo(CN)7] (3) (3-pypz = 2-(1H-pyrazol-3-yl)pyridine, 1-pypz = 2-(1H-pyrazol-1-yl)pyridine, pyim = 2-(1H-imidazol-2-yl)pyridine), have been synthesized and characterized structurally and magnetically. Single crystal X-ray analyses revealed that although the chelating ligands are different, compounds 1 to 3 are isomorphous and crystallize in the same monoclinic space group C2/m...
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Min-Zhuo Cheng, Jing Zhang, Dequan Bao, Xiwei Huang
In this communication, we assembled ordered polystyrene (PS) microsphere array as a template with the drop-coating method, and the oxygen plasma was used to etch the template to adjust the spacing between the PS microspheres. Nano-triangular gold array and silver Nano-pyramid array were obtained by ion beam sputtering to deposit precious metal gold and silver. We observed the surface morphology of Au and Au/Ag composite films by scanning electron microscope and characterized the films by X-ray diffraction and Ultraviolet/visible light spectrophotometer...
May 21, 2018: Electrophoresis
Zhirui Niu, Shaokang Zhang, Lin Zhu
Mn-Zn ferrite (Mn1 - x Zn x Fe2 O4 , x = 0.2, 0.4, 0.6, and 0.8) nanomaterials were prepared by bioleaching and hydrothermal synthesis from waste Zn-Mn batteries. The materials were characterized by XRD, SEM, BET, VSM, CEC, and isoelectric point. It turned out when x = 0.4, synthesized Mn-Zn ferrite had best performance which was nanoferrite crystal structure with a specific surface area that reached 37.77 m2 /g, the saturation magnetization was 62.85 emu/g, and isoelectric point and the CEC value were 7...
May 21, 2018: Environmental Science and Pollution Research International
Aiguo Zhao, Feng Han
In higher plants, the tetrapyrrole biosynthesis pathway starts from the reaction catalyzed by the rate-limiting enzyme, glutamyl-tRNAGlu reductase (GTR). In Arabidopsis thaliana, GTR is controlled by post-transcriptional regulators such as GTR binding protein (GBP), which stimulates AtGTR activity. The NADPH-binding domain of AtGTR undergoes a substantial movement upon GBP binding. Here, we report the crystal structure of AtGTR-NADPH-GBP ternary complex. NADPH binding causes slight structural changes compared with the AtGTR-GBP binary complex, and possibly take a part of the space needed by the substrate glutamyl-tRNAGlu ...
May 21, 2018: Photosynthesis Research
Diamantoula Maniaki, Ioannis Mylonas-Margaritis, Julia Mayans, Aikaterini Savvidou, Catherine P Raptopoulou, Vlasoula Bekiari, Vassilis Psycharis, Albert Escuer, Spyros P Perlepes
The initial use of anils, i.e. bidentate Schiff bases derived from the condensation of anilines with salicylaldehyde or its derivatives, in 4f-metal chemistry is described. The 1 : 1 reactions between Ln(NO3)3·xH2O (Ln = lanthanide) or Y(NO3)3·6H2O and N-(5-bromosalicylidene)aniline (5BrsalanH) in MeCN has provided access to complexes [Ln(NO3)3(5BrsalanH)2(H2O)]·MeCN (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) and [Y(NO3)3(5BrsalanH)2(H2O)]·MeCN, respectively, in good yields. The structures of the isomorphous complexes with Ln = Pr(1·MeCN), Sm(3·MeCN), Gd(5·MeCN), Dy(7·MeCN) and Er(9·MeCN) have been determined by single-crystal X-ray crystallography...
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Przemyslaw Grudnik, Marcin M Kaminski, Krzysztof P Rembacz, Katarzyna Kuska, Mariusz Madej, Jan Potempa, Maciej Dawidowski, Grzegorz Dubin
In higher eukaryotes, several ATP-utilizing enzymes known as hexokinases activate glucose in the glycolysis pathway by phosphorylation to glucose-6-phosphate. In contrast to canonical hexokinases which use ATP, ADP-dependent glucokinase (ADPGK) catalyzes non-canonical phosphorylation of glucose to glucose-6-phosphate using ADP as a phosphate donor. Initially discovered in Archaea, the human homolog of ADPGK was described only recently. ADPGK's involvement in modified bioenergetics of activated T cells has been postulated and elevated ADPGK expression has been reported in various cancer tissues...
May 21, 2018: Journal of Biological Chemistry
Sung Keun Lee, Yong-Hyun Kim, Paul Chow, Yunming Xiao, Cheng Ji, Guoyin Shen
Structural transition in amorphous oxides, including glasses, under extreme compression above megabar pressures (>1 million atmospheric pressure, 100 GPa) results in unique densification paths that differ from those in crystals. Experimentally verifying the atomistic origins of such densifications beyond 100 GPa remains unknown. Progress in inelastic X-ray scattering (IXS) provided insights into the pressure-induced bonding changes in oxide glasses; however, IXS has a signal intensity several orders of magnitude smaller than that of elastic X-rays, posing challenges for probing glass structures above 100 GPa near the Earth's core-mantle boundary...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
Zhenning Ren, Jumin Lee, Mahdi Muhammad Moosa, Yin Nian, Liya Hu, Zhichun Xu, Jason G McCoy, Allan Chris M Ferreon, Wonpil Im, Ming Zhou
The phosphoenolpyruvate-dependent phosphotransferase system (PTS) transports sugar into bacteria and phosphorylates the sugar for metabolic consumption. The PTS is important for the survival of bacteria and thus a potential target for antibiotics, but its mechanism of sugar uptake and phosphorylation remains unclear. The PTS is composed of multiple proteins, and the membrane-embedded Enzyme IIC (EIIC) component transports sugars across the membrane. Crystal structures of two members of the glucose superfamily of EIICs, bcChbC and bcMalT, were solved in the inward-facing and outward-facing conformations, and the structures suggest that sugar translocation could be achieved by movement of a structured domain that contains the sugar-binding site...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
Anabel Laza Correa, Josué M Gonçalves, Pamela O Rossini, Juliana S Bernardes, Carlos A Neves, Koiti Araki, Lucio Angnes
This study reports the preparation and characterization of nickel/lead hydroxide nanoparticles used to construct electrochemical sensors, which were investigated for amperometric quantification of N-acetylcysteine (NAC). The newly synthesised material presents good uniformity, with the lead (II) ions homogenously incorporated into the alpha nickel hydroxide crystal structure, confirmed by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy analyses. Films of nanoparticles (3 nm in size) were prepared on conductive fluorine-doped tin oxide-coated glass slides and used connected to a specially built batch injection analysis (BIA) cell with a capacity of only 4 mL and the electrode positioned in the bottom...
August 15, 2018: Talanta
Subhadip Senapati, Sudipta Biswas, Saikat Manna, Robert Ros, Stuart Lindsay, Peiming Zhang
The goal of this research was to develop linkage chemistry for the study of bivalent interactions between a receptor and its ligand using atomic force microscopy (AFM) and surface plasmon resonance (SPR). We conceived a three-arm structure composed of flexible chains connected to a large rigid core with orthogonal functional groups at their ends for formation and attachment (or immobilization) of bivalent ligands. To demonstrate the principle, we chose the well-known biotin-streptavidin interaction as a model system...
May 21, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
W Zhang, L L Xu, W J Yu, Q Wang, Y X Jiang, Y Liu, Y J Li
Objective: To study the clinicopathologic, immunohistochemical (IHC), histogenetic and prognostic features of acquired cystic kidney disease-associated renal cell carcinoma (ACKD-RCC). Methods: Three cases of ACKD-RCC, including two from 401 Hospital of PLA and one from the Affiliated Hospital of Qingdao University were studied by clinical, histological and IHC analysis with review of relevant literature. Results: All the three patients were male, ranging from 46 to 78 years old. All patients had history of chronic renal failure; two patients were treated with hemodialysis for 9 years and 11 years, respectively...
May 8, 2018: Zhonghua Bing Li Xue za Zhi Chinese Journal of Pathology
José Luis Casas-Hinestroza, Mauricio Maldonado
Reaction between pyrogallol and benzaldehyde results in a conformational mixture of C- tetra(phenyl)pyrogallol[4]arene (crown and chair). The conformer mixture was separated using crystallization procedures and the structures were determined using FTIR, ¹H-NMR, and 13 C-NMR. O -acetylation of C- tetra(phenyl)pyrogallol[4]arene (chair) with acetic anhydride, in pyridine results in the formation of dodecaacetyl-tetra(phenyl)pyrogallol[4]arene. The structure was determined using ¹H-NMR and 13 C-NMR finding that the product maintains the conformation of the starting conformer...
May 20, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
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