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Solid-state NMR

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https://www.readbyqxmd.com/read/28646173/transmembrane-interactions-of-full-length-mammalian-bitopic-cytochrome-p450-cytochrome-b5-complex-in-lipid-bilayers-revealed-by-sensitivity-enhanced-dynamic-nuclear-polarization-solid-state-nmr-spectroscopy
#1
Kazutoshi Yamamoto, Marc A Caporini, Sang-Choul Im, Lucy Waskell, Ayyalusamy Ramamoorthy
The dynamic protein-protein and protein-ligand interactions of integral bitopic membrane proteins with a single membrane-spanning helix play a plethora of vital roles in the cellular processes associated with human health and diseases, including signaling and enzymatic catalysis. While an increasing number of high-resolution structural studies of membrane proteins have successfully manifested an in-depth understanding of their biological functions, intact membrane-bound bitopic protein-protein complexes pose tremendous challenges for structural studies by crystallography or solution NMR spectroscopy...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28644511/bacteriophage-tail-tube-assembly-studied-by-proton-detected-4d-solid-state-nmr
#2
Maximilian Zinke, Pascal Fricke, Camille Samson, Songhwan Hwang, Joseph Wall, Sascha Lange, Sophie Zinn-Justin, Adam Lange
Obtaining unambiguous resonance assignments remains a major bottleneck in solid-state NMR studies of protein structure and dynamics. Particularly for supramolecular assemblies with large subunits (>150 residues), the analysis of crowded spectral data presents a challenge, even if three-dimensional (3D) spectra are used. Here, we present a proton-detected 4D solid-state NMR assignment procedure that is tailored for large assemblies. The key to recording 4D spectra with three indirect carbon or nitrogen dimensions with their inherently large chemical shift dispersion lies in the use of sparse non-uniform sampling (as low as 2%)...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28644384/characterisation-of-the-chemical-composition-and-structural-features-of-novel-antimicrobial-nanoparticles
#3
Yuen-Ki Cheong, Jesus Calvo-Castro, Lena Ciric, Mohan Edirisinghe, Elaine Cloutman-Green, Upulitha Eranka Illangakoon, Qiang Kang, Suntharavathanan Mahalingam, Rupy Kaur Matharu, Rory M Wilson, Guogang Ren
Three antimicrobial nanoparticle types (AMNP0, AMNP1, and AMNP2) produced using the Tesima(TM) thermal plasma technology were investigated and their compositions were determined using a combination of analytical methods. Scanning electron micrographs provided the morphology of these particles with observed sizes ranging from 10 to 50 nm, whilst FTIR spectra confirmed the absence of polar bonds and organic impurities, and strong Raman active vibrational bands at ca. 1604 and 1311 cm(-1) ascribed to C-C vibrational motions were observed...
June 23, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28641673/renewable-modified-cellulose-bearing-chelating-schiff-base-for-adsorptive-removal-of-heavy-metal-ions-and-antibacterial-action
#4
R Saravanan, L Ravikumar
  A novel approach toward chemically modified cellulose bearing active chelating Schiff base with hydroxyl group (Cell-Hy) was synthesized. The modified cellulose was examined for its heavy metal ion uptake potential from aqueous solution. The chemical and structural features of the adsorbent were characterized by Fourier transform infrared spectroscopy (FT-IR), solid state 13C-NMR, Scanning Electron Microscopy (SEM), and energy dispersive analysis of X-ray (EDAX) observations. The experimental conditions and adsorption parameters, including pH, initial metal ion concentration, adsorbent dosage, temperature, and contact time were optimized for the removal of Cu(II) and Pb(II) ions...
July 1, 2017: Water Environment Research: a Research Publication of the Water Environment Federation
https://www.readbyqxmd.com/read/28641413/cation-dynamics-in-mixed-cation-ma-x-fa-1-xpbi3-hybrid-perovskites-from-solid-state-nmr
#5
Dominik Kubicki, Daniel Prochowicz, Albert Hofstetter, Peter Pechy, Shaik M Zakeeruddin, Michael Grätzel, Lyndon Emsley
Mixed cation organic lead halide perovskites attract unfaltering attention owing to their excellent photovoltaic properties. Currently, the best performing perovskite materials contains multiple cations and provide power conversion efficiencies up to around 22%. Here, we report the first quantitative, cation-specific data on cation reorientation dynamics in hybrid mixed-cation formamidinium (FA)/methylammonium (MA) lead halide perovskites. We use 14N, 2H, 13C and 1H solid-state MAS NMR to elucidate cation reorientation dynamics, microscopic phase composition, and the MA/FA ratio, in (MA)x(FA)1-xPbI3 between 100 and 330 K...
June 23, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28638775/host-guest-complexes-of-c-ethyl-2-methylresorcinarene-and-aromatic-n-n-dioxides
#6
Rakesh Puttreddy, Ngong Kodiah Beyeh, Robin H A Ras, Kari Rissanen
The C-ethyl-2-methylresorcinarene (1) forms 1:1 in-cavity complexes with aromatic N,N'-dioxides, only if each of the aromatic rings has an N-O group. The structurally different C-shaped 2,2'-bipyridine N,N'-dioxide (2,2'-BiPyNO) and the linear rod-shaped 4,4'-bipyridine N,N'-dioxide (4,4'-BiPyNO) both form 1:1 in-cavity complexes with the host resorcinarene in C4v crown and C2v conformations, respectively. In the solid state, the host-guest interactions between the 1,3-bis(4-pyridyl)propane N,N'-dioxide (BiPyPNO) and the host 1 stabilize the unfavorable anti-gauche conformation...
June 2017: ChemistryOpen
https://www.readbyqxmd.com/read/28636916/structural-behavior-of-the-peptaibol-harzianin-hk-vi-in-a-dmpc-bilayer-insights-from-md-simulations
#7
Marina Putzu, Sezgin Kara, Sergii Afonin, Stephan L Grage, Andrea Bordessa, Grégory Chaume, Thierry Brigaud, Anne S Ulrich, Tomáš Kubař
Microsecond molecular dynamics simulations of harzianin HK VI (HZ) interacting with a dimyristoylphosphatidylcholine bilayer were performed at the condition of low peptide-to-lipid ratio. Two orientations of HZ molecule in the bilayer were found and characterized. In the orientation perpendicular to the bilayer surface, HZ induces a local thinning of the bilayer. When inserted into the bilayer parallel to its surface, HZ is located nearly completely within the hydrophobic region of the bilayer. A combination of solid-state NMR and circular dichroism experiments found the latter orientation to be dominant...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636347/the-structure-and-dynamics-of-alginate-gels-crosslinked-by-polyvalent-ions-probed-via-solid-state-nmr-spectroscopy
#8
Jiří Brus, Martina Urbanová, Jiri Czernek, Miroslava Pavelkova, Katerina Kubova, Jakub Vyslouzil, Sabina Abbrent, Rafal Konefal, Jiri Horsky, David Vetchy, Jan Vysloužil, Pavel Kulich
Alginate gels are an outstanding biomaterial widely applicable in tissue engineering, medicine, and pharmacy for cell transplantation, wound healing and efficient bioactive agent delivery, respectively. This contribution provides new and comprehensive insight into the atomic-resolution structure and dynamics of polyvalent ion-crosslinked alginate gels in microbead formulations. By applying various advanced solid-state NMR (ssNMR) spectroscopy techniques, we verified the homogenous distribution of the crosslinking ions in the alginate gels and the high degree of ion exchange...
June 21, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28631929/-13-c-dynamic-nuclear-polarization-using-a-trimeric-gd-3-complex-as-an-additive
#9
Peter Niedbalski, Christopher Parish, Qing Wang, Andhika Kiswandhi, Zahra Hayati, Likai Song, Lloyd Laporca Lumata
Dissolution dynamic nuclear polarization (DNP) is one of the most successful techniques that resolves the insensitivity problem in liquid-state nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) by amplifying the signal by several thousand-fold. One way to further improve the DNP signal is the inclusion of trace amounts of lanthanides in DNP samples doped with trityl OX063 free radical as the polarizing agent. In practice, stable monomeric gadolinium complexes such as Gd-DOTA or Gd-HP-DO3A are used as beneficial additives in DNP samples, further boosting the DNP-enhanced solid-state 13C polarization by a factor of 2 or 3...
June 20, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28631856/tetrameric-and-dimeric-n%C3%A2-%C3%A2-%C3%A2-i-%C3%A2-%C3%A2-%C3%A2-n-halogen-bonded-supramolecular-cages
#10
Kari Rissanen, Lotta Turunen, Anssi Peuronen, Samu Forsblom, Elina Kalenius, Manu Lahtinen
Tripodal N-donor ligands are used to form halogen-bonded assemblies via structurally analogous Ag+-complexes. Selective formation of discrete tetrameric I6L4 and dimeric I3L2 halonium cages, wherein multiple [N∙∙∙I+∙∙∙N] halogen bonds are used in concert, can be achieved by using sterically rigidified cationic tris(1-methyl-1-azonia-4-azabicyclo[2.2.2]octane)-mesitylene ligand, L1(PF6)3, and flexible ligand 1,3,5-tris(imidazole-1-ylmethyl)-2,4,6-trimethylbenzene, L2, respectively. The iodonium cages, I6L14(PF6)18 and I3L22(PF6)3, were obtained through the [N∙∙∙Ag+∙∙∙N] → [N∙∙∙I+∙∙∙N] cation exchange reaction between the corresponding Ag6L14(PF6)18 and Ag3L22(PF6)3 coordination cages, prepared as intermediates, and I2...
June 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28631847/conjunction-of-pyrrole-and-amide-moieties-highly-anion-responsive-%C3%AF-electronic-molecules-forming-ion-free-and-ion-pairing-assemblies
#11
Atsuko Kuno, Norimitsu Tohnai, Nobuhiro Yasuda, Hiromitsu Maeda
Dipyrrolyldiketone BF2 complexes with amide units at pyrrole α-positions were synthesized in modest yields and showed extremely high anion-binding affinities due to multiple hydrogen-bonding interactions. The phenyl-amide-substituted derivative formed solid-state chiral helical structures, wherein π planes were oriented parallel to the helical directions. Examination of anion-binding behavior using 1H NMR combined with theoretical studies suggested fast pyrrole inversions, particularly, for the phenyl-amide-substituted derivative...
June 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28629215/unusual-interfacial-freezing-phenomena-in-hexacontane-silica-composites
#12
Xia Gao, Yunlan Su, Weiwei Zhao, Qingyun Qian, Xin Chen, Robert Wittenbrink, Dujin Wang
The crystallization behaviors of n-hexacontane (C60H122)/Stöber silica (SiO2) composites with various compositions were investigated by a combination of differential scanning calorimetry (DSC), solid-state (13)C nuclear magnetic resonance (solid-state (13)C NMR) and Proton NMR relaxation experiments. By means of DSC, C60H122 molecules in C60H122/silica composites were observed to be involved in the interfacial freezing not present in the free bulk C60H122. The orientation of C60H122 molecules, being preferentially normal to silica surface, was confirmed by grazing incidence X-ray diffraction experiments on thin n-hexacontane film adsorbed on the silicon wafer with a native SiO2 layer...
June 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28628906/quadrupolar-nutation-nmr-to-discriminate-central-and-satellite-transitions-spectral-assignments-for-a-ziegler-natta-catalyst
#13
E S Merijn Blaakmeer, Wouter M J Franssen, Arno P M Kentgens
In this contribution we used solid state (35)Cl (I=3/2) quadrupolar NMR to study a MgCl2/2,2-dimethyl-1,3-dimethoxypropane (DMDOMe) adduct that serves as a model system for Ziegler-Natta catalysis. Employing large Radio-Frequency (RF) field strengths we observe three spectral features with strongly varying line widths. The assignment of the spectra is complicated because of the large difference in quadrupolar interactions experienced by the different sites in the system. The satellite transitions (ST) of relatively well-defined bulk Cl sites are partially excited and may overlap with the central transition (CT) resonances of more distorted surface sites...
June 7, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28628721/protonation-of-nitramines-where-does-the-proton-go
#14
Thomas Saal, Martin Rahm, Karl O Christe, Ralf Haiges
The reactions of nitramine, N-methyl nitramine and N,N-dimethyl nitramine with anhydrous HF and the superacids HF/MF5 (M = As, Sb) were investigated at temperatures below -40 °C. In solution, exclusive O-protonation was observed by multinuclear NMR spectroscopy. Whereas no solid product could be isolated from the neat HF solutions even at -78 °C, in the HF/MF5 systems, protonated nitramine MF6- salts were isolated for the first time as moisture-sensitive solids that decompose at temperatures above -40 °C...
June 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28628319/on-the-mechanism-of-phenol-alkylation-in-zeolite-h-bea-using-in-situ-solid-state-nmr-spectroscopy
#15
Zhenchao Zhao, Hui Shi, Chuan Wan, Mary Y Hu, Yuanshuai Liu, Donghai Mei, Donald M Camaioni, Jian Zhi Hu, Johannes A Lercher
The reaction mechanism of solid-acid-catalyzed phenol alkylation with cyclohexanol and cyclohexene in the apolar solvent decalin has been studied using in situ (13)C MAS NMR spectroscopy. Phenol alkylation with cyclohexanol sets in only after a majority of cyclohexanol is dehydrated to cyclohexene. As phenol and cyclohexanol show similar adsorption strength, this strict reaction sequence is not caused by the limited access of phenol to cyclohexanol, but is due to the absence of a reactive electrophile as long as a significant fraction of cyclohexanol is present...
June 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28623034/new-nmr-tools-for-protein-structure-and-function-spin-tags-for-dynamic-nuclear-polarization-solid-state-nmr
#16
Rivkah Rogawski, Ann McDermott
Magic angle spinning solid state NMR studies of biological macromolecules [1-3] have enabled exciting studies of membrane proteins [4,5], amyloid fibrils [6], viruses, and large macromolecular assemblies [7]. Dynamic nuclear polarization (DNP) provides a means to enhance detection sensitivity for NMR, particularly for solid state NMR, with many recent biological applications and considerable contemporary efforts towards elaboration and optimization of the DNP experiment. This review explores precedents and innovations in biological DNP experiments, especially highlighting novel chemical biology approaches to introduce the radicals that serve as a source of polarization in the DNP experiments...
June 13, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28621934/tqopen-n-n-n-n-tetrakis-2-quinolylmethyl-3-oxa-1-5-pentanediamine-family-as-heptadentate-fluorescent-cd-2-sensors
#17
Yuji Mikata, Asako Kizu, Kana Nozaki, Hideo Konno, Hiroshi Ono, Shunsuke Mizutani, Shin-Ichiro Sato
A quinoline-based heptadentate ligand, N,N,N',N'-tetrakis(2-quinolylmethyl)-3-oxa-1,5-pentanediamine (TQOPEN), exhibits a fluorescence increase (ICd/I0 = 25, ϕCd = 0.017) at 428 nm upon addition of 1 equiv of Cd(2+). In contrast, 1 equiv of Zn(2+) induces a negligible fluorescence change due to weak interaction (IZn/I0 = 2.5, IZn/ICd = 10%). In comparison with TQOPEN, the thia and aza derivatives TQSPEN and TQNPEN exhibit improved Cd(2+)/Zn(2+) selectivity and higher Cd(2+)-binding affinity, respectively. The solid-state structures of mononuclear Cd(2+) and hydroxide-bridged dinuclear Zn(2+) complexes of TQOPEN were elucidated by X-ray crystallography...
June 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28621522/formation-and-structure-of-wild-type-huntingtin-exon-1-fibrils
#18
J Mario Isas, Andreas Langen, Myles C Isas, Nitin Kumar Pandey, Ansgar B Siemer
The fact that the heritable neurodegenerative disorder Huntington's Disease (HD) is autosomal dominant means that there is one wild type and one mutant allele in most HD patients. The CAG repeat expansion in the exon 1 of the protein huntingtin (HTTex1) that causes the disease, leads to the formation of HTT fibrils in vitro and vivo. An important question for understanding the molecular mechanism of HD is which role wild type HTT plays for the formation, propagation, and structure of these HTT fibrils. Here we report that fibrils of mutant HTTex1 are able to seed the aggregation of wild type HTTex1 into amyloid fibrils which in turn can seed the fibril formation of mutant HTTex1...
June 16, 2017: Biochemistry
https://www.readbyqxmd.com/read/28621371/does-z-equal-1-or-2-enhanced-powder-nmr-crystallography-verification-of-a-disordered-room-temperature-crystal-structure-of-a-p38-inhibitor-for-chronic-obstructive-pulmonary-disease
#19
Cory M Widdifield, Sten O Nilsson Lill, Anders Broo, Maria Lindkvist, Anna Pettersen, Anna Svensk Ankarberg, Peter Aldred, Staffan Schantz, Lyndon Emsley
The crystal structure of the Form A polymorph of N-cyclopropyl-3-fluoro-4-methyl-5-[3-[[1-[2-[2-(methylamino)ethoxy]phenyl]cyclopropyl]amino]-2-oxo-pyrazin-1-yl]benzamide (i.e., AZD7624), determined using single-crystal X-ray diffraction (scXRD) at 100 K, contains two molecules in the asymmetric unit (Z' = 2) and has regions of local static disorder. This substance has been in phase IIa drug development trials for the treatment of chronic obstructive pulmonary disease, a disease which affects over 300 million people and contributes to nearly 3 million deaths annually...
June 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28621361/single-site-silica-supported-tetramethyl-niobium-by-the-somc-strategy-synthesis-characterization-and-structure-activity-relationship-in-the-ethylene-oligomerization-reaction
#20
Ali Hamieh, Raju Dey, Bijan Nekoueishahraki, Manoja K Samantaray, Yin Chen, Edy Abou-Hamad, Jean-Marie Basset
A silica supported tetramethyl niobium complex [([triple bond, length as m-dash]SiO)NbMe4] 2 has been isolated by the surface alkylation of [([triple bond, length as m-dash]SiO-)NbCl3Me] 1 with dimethyl zinc in pentane. 1 can be easily synthesized by grafting NbCl3Me2 onto the surface of partially dehydroxylated silica by the SOMC strategy. Precise structural analysis was carried out using FTIR, advanced solid state NMR, elemental analysis and mass balance techniques (gas quantification after treating 2 with degassed water)...
June 16, 2017: Chemical Communications: Chem Comm
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