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Solid state NMR

Guillaume David, Marie-Laure Fogeron, Maarten Schledorn, Roland Montserret, Uta Haselmann, Susanne Penzel, Aurelie Badillo, Lauriane Lecoq, Patrice André, Michael Nassal, Ralf Bartenschlager, Beat H Meier, Anja Böckmann
Viral membrane proteins are prime targets in the combat against infection. Still, their structure determination remains a challenge, both with respect to sample preparation, and the need for structural methods allowing analysis in a native-like lipid environment. Cell-free protein synthesis and solid-state NMR are promising approaches in this context, one with respect to its high potential of native expression of complex proteins, and the other for its ability to analyze membrane proteins in lipids. We here show that milligram amounts of the small envelope protein of the duck hepatitis B virus (DHBV) can be produced using cell-free expression, and that the protein self-assembles into subviral particles...
February 19, 2018: Angewandte Chemie
James R Banigan, Maureen Leninger, Ampon Sae Her, Nathaniel J Traaseth
It is known that the lipid composition within a cellular membrane can influence membrane protein structure and function. In this Article, we investigated how structural changes to a membrane protein upon substrate binding can impact the lipid bilayer. To carry out this study, we reconstituted the secondary active drug transporter EmrE into a variety of phospholipid bilayers varying in headgroup and chain length and carried out differential scanning calorimetry (DSC) and solid-state NMR experiments. The DSC results revealed a difference in cooperativity of the lipid phase transition for drug-free EmrE protonated at glutamic acid 14 (i...
February 19, 2018: Journal of Physical Chemistry. B
Khairia M Al-Ahmary, Moustafa M Habeeb, Areej H Al-Obidan
New charge transfer complex (CTC) between the electron donor 2,3-diaminopyridine (DAP) with the electron acceptor chloranilic (CLA) acid has been synthesized and characterized experimentally and theoretically using a variety of physicochemical techniques. The experimental work included the use of elemental analysis, UV-vis, IR and 1 H NMR studies to characterize the complex. Electronic spectra have been carried out in different hydrogen bonded solvents, methanol (MeOH), acetonitrile (AN) and 1:1 mixture from AN-MeOH...
February 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Ana Topete, Andreia S Oliveira, A Fernandes, T G Nunes, A P Serro, B Saramago
Although the possibility of using drug-loaded ophthalmic lens to promote sustained drug release has been thoroughly pursued, there are still problems to be solved associated to the different alternatives. In this work, we went back to the traditional method of drug loading by soaking in the drug solution and tried to optimize the release profiles by changing the temperature and the time of loading. Two materials commercially available under the names of CI26Y and Definitive 50 were chosen. CI26Y is used for intraocular lenses (IOLs) and Definitive 50 for soft contact lenses (SCLs)...
February 14, 2018: European Journal of Pharmaceutical Sciences
Lauriane Lecoq, Shishan Wang, Thomas Wiegand, Stéphane Bressanelli, Michael Nassal, Beat H Meier, Anja Böckmann
Each year, nearly 900,000 deaths are due to serious liver diseases caused by chronic hepatitis B virus infection. The viral particle is composed of an outer envelope and an inner icosahedral nucleocapsid formed by multiple dimers of a ~ 20 kDa self-assembling core protein (Cp). Here we report the solid-state 13 C and 15 N resonance assignments of the assembly domain, Cp149, of the core protein in its capsid form. A secondary chemical shift analysis of the 140 visible residues suggests an overall alpha-helical three-dimensional fold matching that derived for Cp149 from the X-ray crystallography of the capsid, and from solution-state NMR of the Cp149 dimer...
February 16, 2018: Biomolecular NMR Assignments
A Ryzhikov, H Nouali, T J Daou, J Patarin
High pressure intrusion-extrusion of concentrated solutions of sodium salts in a pure-silica MFI-type zeolite (Silicalite-1) was studied for potential applications in mechanical energy absorption and storage. It was discovered that the anion nature has a drastic influence on the behavior and the energetic performances of "Silicalite-1 - concentrated Na + X - solution" systems, where X = Cl - , Br - , I - , NO 2 - , NO 3 - , ClO 4 - and CrO 4 2- . In the case of NaNO 2 , NaClO 4 , Na 2 CrO 4 , and NaI a combination of bumper and shock-absorber behaviors with a partial irreversible solution intrusion was observed, whereas a fully reversible spring behavior is demonstrated for the intrusion-extrusion of NaBr, NaCl and NaNO 3 solutions...
February 15, 2018: Physical Chemistry Chemical Physics: PCCP
Elena Petracovschi, Laurent Calvez, Laurent Cormier, David LE Coq, Jincheng Du
The short and medium range structures of the 80GeSe2-20Ga2Se3 (or Ge23.5Ga11.8Se64.7) chalcogenide glasses have been studied by combining ab initio molecular dynamics (AIMD) simulations and experimental neutron diffraction studies. Structure factor and total correlation function were calculated from glass structures generated from AIMD simulations and compared with neutron diffraction experiments showing reasonable agreement. The atom structures of the ternary chalcogenide glasses were analyzed in detailed and it was found that gallium atoms are four-fold coordinated by selenium and form [GaSe4] tetrahedra...
February 14, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Evamarie Hey-Hawkins, Jan Schulz, Anika Kreienbrink, Peter Coburger, Benedikt Schwarze, Toni Grell, Peter Lönnecke
Carborane-substituted 1,2-diphosphetanes (Ia,b) react with lithium in THF with cleavage of the P-P bond to give a deep red solution from which red crystals of a lithiated intermediate, [{1-PtBuLi(THF)-6-PtBu-4,1,6-closo-Li(THF)C2B10H10}{Li(THF)3}]2∙ 2 THF (2), were obtained. The compound is dimeric and contains six Li and four P atoms. Two Li atoms are capping the six-membered C2B4 faces resulting in two 13-vertex closo-clusters with docosahedral geometry. Addition of MeI resulted in formation of the zwitterionic bis-phosphonium-nido-carborates, 7,10-bis(tert-butyl-dimethylphosphonium)-dodecahydro-7,10-dicarba-nido-dodecaborate(2-) (1a) and 7,10-bis(N,N-diisopropylamino-dimethylphosphonium)-dodecahydro-7,10-dicarba-nido-dodecaborate(2-) (1b) in moderate to good yields...
February 13, 2018: Chemistry: a European Journal
Laura C E da Silva, Luiz G L Germiniani, Tomás S Plivelic, Maria C Gonçalves
Biocompatible chemically cross-linked organic-inorganic (O-I) hybrid nanocomposites were developed using a new atoxic, simple and fast, solvent-free pathway. Poly(ε-caprolactone) (PCL) and poly(ethylene glycol) (PEG), which are both biocompatible, were used as the organic moieties (at different PCL/PEG ratios), while in situ synthesized polysilsesquioxanes made up the inorganic moiety. The O-I hybrid nanocomposites' molecular structures were characterized using solid-state 29Si NMR, TGA and ATR-IR. Results showed an unusually high condensation yield of approximately 90% and two distinct silsesquioxane structures...
February 12, 2018: Soft Matter
Maryam Ghanadpour, Bernd Wicklein, Federico Carosio, Lars Wågberg
Pure cellulosic foams suffer from low thermal stability and high flammability, limiting their fields of application. Here, light-weight and flame-resistant nanostructured foams are produced by combining cellulose nanofibrils prepared from phosphorylated pulp fibers (P-CNF) with microfibrous sepiolite clay using the freeze-casting technique. The resultant nanocomposite foams show excellent flame-retardant properties such as self-extinguishing behavior and extremely low heat release rates in addition to high flame penetration resistance attributed mainly to the intrinsic charring ability of the phosphorylated fibrils and the capability of sepiolite to form heat-protective intumescent-like barrier on the surface of the material...
February 12, 2018: Nanoscale
Luther Wang, Fernando J Uribe-Romo, Leonard J Mueller, James K Harper
The hydrogen-bonding environments at the COOH moiety in eight polycrystalline polymorphs of palmitic acid are explored using solid-state NMR. Although most phases have no previously reported crystal structure, measured 13C chemical shift tensors for COOH moieties, combined with DFT modeling establish that all phases crystallize with a cyclic dimer (R(8)) hydrogen bonding arrangement. Phases A2, Bm and Em have localized OH hydrogens while phase C has a dynamically disordered OH hydrogen. The phase designated As is a mix of five forms, including 27...
February 12, 2018: Physical Chemistry Chemical Physics: PCCP
Peiren Liu, Zhengtao Li, Bingbing Shi, Jiyong Liu, Huangtianzhi Zhu, Feihe Huang
Linear side-chain polypseudorotaxane with supramolecular polymer backbone was assembled by neutral halogen bonds (XB) and pillar[5]arene-based host-guest interactions in solution and in the solid state. The formation of the halogen-bonded supramolecular polymer backbone and side-chain polypseudorotaxane in solution was characterized by 1H NMR spectroscopy, diffusion ordered NMR spectroscopy and scanning electron microscopy experiments. Furthermore, the solid-state structures of these two highly organized supramolecular architectures were provided by single crystal X-ray analysis...
February 12, 2018: Chemistry: a European Journal
Lila Bouëssel Du Bourg, Eric Furet, Alicia Lecomte, Laurent Le Pollès, Shinji Kohara, Chris J Benmore, Eugène Bychkov, David Le Coq
The structure of the binary chalcohalide glasses Te1-xClx (0.35 ≤ x ≤ 0.65) is considered by combining experimental and theoretical results. The structural network properties are influenced by a competition between ionic and covalent bonding in such glasses. At first, a focus is placed on the detailed information available by using the complementary high-energy X-ray and the neutron diffractions in both the reciprocal and real spaces. The main characteristic suggested by the structure factors S(Q) concerns the presence of three length scales in the intermediate range order...
February 12, 2018: Inorganic Chemistry
Xiudan Hou, Xiaofeng Lu, Panhong Niu, Sheng Tang, Licheng Wang, Yong Guo
A new three-dimensional graphene oxide wrapped melamine foam was prepared and used as a solid-phase extraction substrate. β-Cyclodextrin was fabricated onto the surface of three-dimensional graphene oxide-wrapped melamine foam by a chemical covalent interaction. In view of a specific surface area and a large delocalized π electron system of graphene oxide, combing with a hydrophobic interior cavity and a hydrophilic peripheral face of β-cyclodextrin, the prepared extraction material was proposed for the determination of flavonoids...
February 12, 2018: Journal of Separation Science
Gregory Lusk, Terry Gullion
Some MAS NMR experiments are sensitive to fluctuations or drifts in rf field strengths. We examine the simple 1H-13C CPMAS experiment and show that the 13C signal intensities vary over time due to drifts in rf field strengths. The causes of the drifts in rf field strengths are studied. Stabilization of the rf field strengths are obtained by using an rf field-strength controller. The controller is a stand-alone unit, which can be easily incorporated in any spectrometer system. Details of the controller, including circuit design, are provided...
February 3, 2018: Solid State Nuclear Magnetic Resonance
Inimfon A Udoetok, Lee D Wilson, John V Headley
Cross-linked cellulose-epichlorohydrin polymers were synthesized by a conventional heating with stirring (C-EP heating) and a parallel process using ultra-sonication (C-EP sonication) in the presence of aqueous ammonia. Structural characterization of modified cellulose was carried out using FTIR/13C solid state NMR spectroscopy and thermal methods (DSC and TGA). Evidence of products with variable textural properties and morphology was supported by nitrogen gas adsorption, solvent swelling, and microscopy (SEM, TEM) results...
April 2018: Ultrasonics Sonochemistry
Dominik Kubicki, Daniel Prochowicz, Albert Hofstetter, Marcin Saski, Pankaj Yadav, Dongqin Bi, Norman Pellet, Janusz Lewinski, Shaik M Zakeeruddin, Michael Grätzel, Lyndon Emsley
Methylammonium (MA)- and formamidinium (FA)-based organic-inorganic lead halide perovskites provide outstanding performance as photovoltaic materials, due to their versatility of fabrication and their power conversion efficiencies reaching over 22%. The proposition of guanidinium (GUA)-doped perovskite materials generated considerable interest due to their potential to increase carrier lifetimes and open circuit voltages as compared to pure MAPbI3. However, simple size considerations based on the Goldschmidt tolerance factor suggest that guanidinium is too big to completely replace methylammonium as an A cation in the APbI3 perovskite lattice, and its effect was thus ascribed to passivation of surface trap states at grain boundaries...
February 11, 2018: Journal of the American Chemical Society
Bhisma Narayan Ratha, Minsoo Kim, Bankanidhi Sahoo, Kanchan Garai, DongKuk Lee, Anirban Bhunia
Injection of exogenous insulin in the subcutaneous mass has been a proven therapy for type II diabetes. However, chronic administration of insulin often develops local amyloidosis at the injection site, pathologically known as "Insulin Ball". This reduces the insulin bioavailability and exacerbates the disease pathology. Thus, the molecular interaction between insulin and the recipient's membrane surface plays a co-operative role in accelerating the amyloidosis. This interaction, however, is different from the molecular interaction of insulin with the native membranous environment of the pancreatic β-cells...
February 8, 2018: Biochimica et Biophysica Acta
Patrick G Hatcher, Wassim Obeid, Andrew S Wozniak, Chen Xu, Saijin Zhang, Peter H Santschi, Antonietta Quigg
The Deepwater Horizon oil spill stimulated the release of marine snow made up of dead/living plankton/bacteria and their exopolymeric polysaccharide substances (EPS), termed marine oil snow (MOS), promoting rapid removal of oil from the water column into sediments near the well site. Mesocosm simulations showed that Macondo surrogate oil readily associates with the marine snow. Quantitative solid-state 13C NMR readily distinguishes this oil from naturally formed marine snow and reveals that adding the dispersant Corexit enhances the amount of oil associated with the MOS, thus contributing to rapid removal from the water column...
January 2018: Marine Pollution Bulletin
Marc-Antoine Sani, Pierre-Alexandre Martin, Ruhamah Yunis, Fangfang Chen, Maria Forsyth, Michael Deschamps, Luke A O'Dell
Dynamic nuclear polarisation (DNP) enhanced solid-state NMR spectroscopy has been used to study an ionic liquid salt solution (N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide, C3mpyrFSI, containing 1.0 m lithium bis(fluorosulfonyl)imide, 6LiFSI) in its glassy state at a temperature of 92 K. The incorporation of a biradical to enable DNP signal enhancement allowed the proximities of the lithium to the individual carbon sites on the pyrrolidinium cation to be probed using a 13C-6Li REDOR pulse sequence...
February 8, 2018: Journal of Physical Chemistry Letters
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