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Quinlin M Hanson, Jeffrey R Carley, Tyler J Gilbreath, Brian C Smith, Eric S Underbakke
Nitric oxide synthase (NOS) is the primary generator of nitric oxide signals controlling diverse physiological processes such as neurotransmission and vasodilation. NOS activation is contingent on Ca2+ /calmodulin binding at a linker between its oxygenase and reductase domains to induce large conformational changes that orchestrate inter-domain electron transfer. However, the structural dynamics underlying activation of full-length NOS remain ambiguous. Employing hydrogen-deuterium exchange mass spectrometry, we reveal mechanisms underlying neuronal NOS (nNOS) activation by calmodulin and regulation by phosphorylation...
February 16, 2018: Journal of Molecular Biology
Sanaa E Tork, Magda M Aly, Omar Elsemin
In the current study, the purified l-glutaminase from Streptomyces pratensis NRC10 (GenBank number KC857622) was characterized. Its molecular weight was estimated to be 46 kDa and isoelectric point 7.4. Its Vmax was calculated to be 2.19 U/mg/min, while Km was 0.175 mM. The optimum pH and temperature were 9 and 45 °C, respectively. It was thermostable at 45 °C but thermally inactivated at 60 °C after 50 min. Moreover, its enzymatic activity was enhanced by K+ ions and inhibited by Mg2+ , Cu2+ , Ag+ , Hg2+ , Ni2+ , Fe2+ , Cr2 , Na+ , Ca2+ , and EDTA...
February 16, 2018: International Journal of Biological Macromolecules
Wei Zhang, Qianqian Zheng, Mengrong Yan, Xiaobo Chen, Haitao Yang, Weihong Zhou, Zihe Rao
HCoV-229E spike (S) protein mediates virion attachment to cells and subsequent fusion of the viral and cellular membranes. This protein is composed of an N-terminal receptor-binding domain (S1) and a C-terminal trans-membrane fusion domain (S2). S2 contains a highly conserved heptad repeat 1 and 2 (HR1 and HR2). In this study, the HRs sequences were designed and connected with a flexible linker. The recombinant fusion core protein was crystallized and its structure was solved at a resolution of 2.45 Å. Then we characterized the binding of HR1s and HR2s via both sequence alignment and structural analysis...
February 16, 2018: Biochemical and Biophysical Research Communications
Joachim Laun, Wouter Marchal, Vanessa Trouillet, Alexander Welle, An T Hardy, Marlies K Van Bael, Christopher Barner-Kowollik, Tanja Junkers
Efficient and simple polymer conjugation reactions are critical for introducing functionalities on surfaces. For polymer surface grafting, post polymerization modifications are often required, which can impose a significant synthetic hurdle. Here, we report two strategies that allow for reversible surface engineering via nitrone-mediated radical coupling (NMRC). Macroradicals stemming from activation of polymers generated by copper-mediated radical polymerization are grafted via radical trapping with a surface-immobilized nitrone or a solution-borne nitrone...
February 19, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Hediye Irem Ozgunduz, Abdullah Bilal Ozturk, Hava Gizem Kandilci, Nil Acarali
The aim of this study is to produce the smart hydrogel to use insulin release for human body. p(HEMA-co-Eudragit L-100) hydrogels containing different ratios of 2-Hydroxyethyl methacrylate (HEMA) and Eudragait L-100 were synthesized by using ammonium persulfate (APS) as an initiator and ethylene glycol dimethacrylate (EGDMA) as a cross linker. The structures of hydrogels produced were characterized by using Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning electron microscope (SEM) analysis. In this way, optimum synthesis conditions were determined for p(HEMA-co-Eudragit L-100) hydrogels by using Taguchi method as an optimization method...
2018: Bio-medical Materials and Engineering
Satoshi Kawabata, Naoki Ousaka, Eiji Yashima
A helical foldamer possessing conformationally switchable metal-binding linkers underwent supramolecular polymerization to form a helical nanofiber. A reversible helix-to-helix transition of the helical nanofiber took place upon cooperative binding and release of Ag(i) ions via a metal-coordination-driven W-to-U-shape conformational change of the linkers in a positive allosteric manner.
February 19, 2018: Chemical Communications: Chem Comm
Mikel M Arbulo-Echevarria, Isaac Narbona-Sánchez, Cecilia M Fernandez-Ponce, Inmaculada Vico-Barranco, Mª Dolores Rueda-Ygueravide, Michael L Dustin, Arkadiusz Miazek, Mª Carmen Duran-Ruiz, Francisco García-Cózar, Enrique Aguado
The adaptor protein linker for activation of T cells (LAT) has an essential role transducing activatory intracellular signals coming from the TCR/CD3 complex. Previous reports have shown that upon T-cell activation, LAT interacts with the tyrosine kinase Lck, leading to the inhibition of its kinase activity. LAT-Lck interaction seemed to depend on a stretch of negatively charged amino acids in LAT. Here, we have substituted this segment of LAT between amino acids 113 and 126 with a non-charged segment and expressed the mutant LAT (LAT-NIL) in J...
2018: Frontiers in Immunology
John Christopher, Zoltán Orgován, Miles Congreve, Andrew S Dore, James C Errey, Fiona H Marshall, Jonathan S Mason, Krzysztof Okrasa, Prakash Rucktooa, Maria J Serrano-Vega, György G Ferenczy, Gyorgy M Keseru
Two interesting new X-ray structures of negative allosteric modulator (NAM) ligands for the mGlu5 receptor, M-MPEP (3) and fenobam (4), are reported. The new structures show how the binding of the ligands induces different receptor water channel conformations to previously published structures. The structure of fenobam, where a urea replaces the acetylenic linker in M-MPEP and mavoglurant, reveals a binding mode where the ligand is rotated by 180º compared to a previously proposed docking model. The need for multiple ligand structures for accurate GPCR structure-based drug design is demonstrated by the different growing vectors identified for the head groups of M-MPEP and mavoglurant and by the unexpected water mediated receptor interactions of a new chemotype represented by fenobam...
February 18, 2018: Journal of Medicinal Chemistry
Defu Zhi, Yuchao Bai, Jian Yang, Shaohui Cui, Yinan Zhao, Huiying Chen, Shubiao Zhang
Cationic lipids have become known as one of the most versatile tools for the delivery of DNA, RNA and many other therapeutic molecules, and are especially attractive because they can be easily designed, synthesized and characterized. Most of cationic lipids share the common structure of cationic head groups and hydrophobic portions with linker bonds between both domains. The linker bond is an important determinant of the chemical stability and biodegradability of cationic lipid, and further governs its transfection efficiency and cytotoxicity...
December 26, 2017: Advances in Colloid and Interface Science
Jack Carson, Charlotte M Thomas, Aaron McGinty, Gustavo Takata, David J Timson
Schistosoma mansoni, like other trematodes, expresses a number of unusual calcium binding proteins which consist of an EF-hand domain joined to a dynein light chain-like (DLC-like) domain by a flexible linker. These proteins have been implicated in host immune responses and drug binding. Three members of this protein family from S. mansoni (SmTAL1, SmTAL2 and SmTAL3) have been well characterised biochemically. Here we characterise the remaining family members from this species (SmTAL4-13). All of these proteins form homodimers and all except SmTAL5 bind to calcium and manganese ions...
February 14, 2018: Molecular and Biochemical Parasitology
Yue Zhang, Kewei Ren, Xiaobo Zhang, Zhicong Chao, Yuqin Yang, Deju Ye, Zhihui Dai, Ying Liu, Huangxian Ju
RNA interference (RNAi) has become an appealing therapeutic approach for cancer and other diseases. One key challenge is the effective protection of these small fragile biomolecules against complicated physiological environments as well as efficient on-demand release. Here we design a photo-tearable polymer tape close-wrapped nanocapsule for efficient NIR modulated siRNA delivery. The photo-tearable nanocapsules comprise core-shell upconversion nanoparticles (UCNPs) coated with mesoporous silica layer for loading of photosensitizer hypocrellin A (HA) and small interfering RNA (siRNA) against polo-like kinase 1 (PLK1), and covalently bound thin membranes of polyethylene glycol (PEG) via a synthesized photocleavable linker (PhL)...
February 9, 2018: Biomaterials
Mohamed F Zidan, Hany M Ibrahim, Mohsen I Afouna, Elsherbeny A Ibrahim
The aim of this study was to explore the feasibility of complexing the poorly water-soluble drug atorvastatin calcium (AC) with β-cyclodextrin (β-CD) based nanosponges (NS), which offer advantages of improving dissolution rate and eventually oral bioavailability. Blank NS were fabricated at first by reacting β-CD with the cross-linker carbonyldiimidazole at different molar ratios (1:2, 1:4 and 1:8), then NS of highest solubilization extent for AC were complexed with AC. AC loaded NS (AC-NS) were characterized for various physicochemical properties...
February 16, 2018: Drug Development and Industrial Pharmacy
Jan Hynek, Petr Brázda, Jan Rohlíček, Michael G S Londesborough, Jan Demel
Metal-organic frameworks (MOFs) are a chemically and topologically diverse family of materials composed of inorganic nodes and organic linkers bound together by coordination bonds. In this contribution we present two significant innovations in this field. The first is the use of a new coordination group in phenylene-1,4-bis(methylphosphinic acid) (PBPA), a phosphinic acid analogue of commonly-used terephtalic acid. We show that the use of this new linker group leads to the formation of a hydrothermally stable permanently porous MOF structure...
February 16, 2018: Angewandte Chemie
Tom Stennett, James Mattock, Ivonne Vollert, Alfredo Vargas, Holger Braunschweig
Cyclic diboranes(4) based on a chelating monoanionic benzylphosphine linker were prepared by boron-silicon exchange between arylsilanes and B2Br4. Coordination of Lewis bases to the remaining sp2 boron atom yielded unsymmetrical sp3-sp3 diboranes, which were reduced with KC8 to their corresponding trans-diborenes. These compounds were studied by a combination of spectroscopic methods, X-ray diffraction and DFT calculations. PMe3-stabilized diborene 6 was found to undergo thermal rearrangement to gem-diborene 8...
February 16, 2018: Angewandte Chemie
Pedro Serrano, John A Hammond, Michael Geralt, Kurt Wüthrich
Splicing factor RBM10 and its close homologues RBM5 and RBM6 govern the splicing of oncogenes such as Fas, NUMB, and Bcl-X. The molecular architecture of these proteins includes zinc fingers (ZnFs) and RNA recognition motifs (RRMs). Three of these domains in RBM10 that constitute the RNA binding part of this splicing factor were found to individually bind RNAs with micromolar affinities. It was thus of interest to further investigate the structural basis of the well-documented high-affinity RNA recognition by RMB10...
February 16, 2018: Biochemistry
Jie Wang, Jing Tang, Bing Ding, Zhi Chang, Xiaodong Hao, Toshiaki Takei, Naoya Kobayashi, Yoshio Bando, Xiaogang Zhang, Yusuke Yamauchi
Metal-organic frameworks (MOFs) have become a research hotspot since they have been explored as convenient precursors for preparing various multifunctional nanomaterials. However, the preparation of MOF networks with controllable flake morphology in large scale is not realized yet. Herein, a self-template strategy is developed to prepare MOF networks. In this work, layered double-metal hydroxide (LDH) and other layered metal hydroxides are used not only as a scaffold but also as a self-sacrificed metal source...
February 16, 2018: Small
Josie E Auckett, Samuel G Duyker, Ekaterina I Izgorodina, Chris S Hawes, David R Turner, Stuart R Batten, Vanessa Kate Peterson
The interdependent effects of temperature and guest uptake on the structure of the ultramicroporous metal-organic framework [Cu3(cdm)4] (cdm = C(CN)2(CONH2)-) are explored in detail using in situ neutron scattering and density functional theory calculations. The tetragonal lattice displays an anisotropic thermal response related to a hinged "lattice-fence" mechanism, unusual for this topology, which is facilitated by pivoting of the rigid cdm anion about the Cu nodes. Calculated pore size metrics clearly illustrate the potential for temperature-mediated adsorption in ultramicroporous frameworks due to thermal fluctuations of the pore diameter near the value of the target guest kinetic diameter, though in [Cu3(cdm)4] this is counteracted by a competing contraction of the pore with increasing temperature as a result of the anisotropic lattice response...
February 16, 2018: Chemistry: a European Journal
Alexander E J Hoffman, Louis Vanduyfhuys, Irena Nevjestić, Jelle Wieme, Sven M J Rogge, Hannes Depauw, Pascal Van Der Voort, Henk Vrielinck, Veronique Van Speybroeck
In this work, mid-infrared (mid-IR), far-IR, and Raman spectra are presented for the distinct (meta)stable phases of the flexible metal-organic framework MIL-53(Al). Static density functional theory (DFT) simulations are performed, allowing for the identification of all IR-active modes, which is unprecedented in the low-frequency region. A unique vibrational fingerprint is revealed, resulting from aluminum-oxide backbone stretching modes, which can be used to clearly distinguish the IR spectra of the closed- and large-pore phases...
February 8, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Zhongyuan Zhou, Xiushuang Xing, Chongbin Tian, Wei Wei, Dejing Li, Falu Hu, Shaowu Du
A new Zn-cluster based MOF, [Zn 21 (BTC) 11 (μ 3 -OH) 3 (μ 4 -O) 3 (H 2 O) 18 ]·21EtOH (1) (H 3 BTC = 1,3,5-benzenetricarboxylic acid), with two different types of cluster nodes has been successfully synthesized from Zn 2+ and H 3 BTC under the solvothermal conditions. Single crystal X-ray diffraction studies reveal that 1 is a 3D trinodal (3,5,6)-c framework which features a large octahedral cage organized by nine Zn 3 O and nine Zn 4 O clusters SBUs and twenty-four triangular BTC 3- linkers. The Eu 3+ /Tb 3+ -incorporated derivative of 1 with 0...
February 15, 2018: Scientific Reports
Tran Thi Thu Trang, Lise Dieltjens, Geert Hooyberghs, Kai Waldrant, Denis S Ermolat'ev, Erik V Van der Eycken, Hans P L Steenackers
The increased tolerance of biofilms against disinfectants and antibiotics has stimulated research into new methods of biofilm prevention and eradication. In our previous work, we have identified the 5-aryl-2-aminoimidazole core as a scaffold that demonstrates preventive activity against biofilm formation of a broad range of bacterial and fungal species. Inspired by the dimeric nature of natural 2-aminoimidazoles of the oroidin family, we investigated the potential of dimers of our decorated 5-aryl-2-aminoimidazoles as biofilm inhibitors...
January 31, 2018: Bioorganic & Medicinal Chemistry
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