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Solid-state NMR

Beat H Meier, Roland Riek, Anja Böckmann
Amyloid structures at atomic resolution have remained elusive mainly because of their extensive polymorphism and because their polymeric properties have hampered structural studies by classical approaches. Progress in sample preparation, as well as solid-state NMR methods, recently enabled the determination of high-resolution 3D structures of fibrils such as the amyloid-β fibril, which is involved in Alzheimer's disease. Notably, the simultaneous but independent structure determination of Aβ1-42, a peptide that forms fibrillar deposits in the brain of Alzheimer patients, by two independent laboratories, which yielded virtually identical results, has highlighted how structures can be obtained that allow further functional investigation...
September 12, 2017: Trends in Biochemical Sciences
Phillip J Milner, Rebecca L Siegelman, Alexander C Forse, Miguel I Gonzalez, Tomče Runčevski, Jeffrey D Martell, Jeffrey A Reimer, Jeffrey R Long
A new diamine-functionalized metal-organic framework comprised of 2,2-dimethyl-1,3-diaminopropane (dmpn) appended to the Mg(2+) sites lining the channels of Mg2(dobpdc) (dobpdc(4-) = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) is characterized for the removal of CO2 from the flue gas emissions of coal-fired power plants. Unique to members of this promising class of adsorbents, dmpn-Mg2(dobpdc) displays facile step-shaped adsorption of CO2 from coal flue gas at 40 °C and near complete CO2 desorption upon heating to 100 °C, enabling a high CO2 working capacity (2...
September 14, 2017: Journal of the American Chemical Society
Trivikram R Molugu, Soohyun Lee, Michael F Brown
Concepts of solid-state NMR spectroscopy and applications to fluid membranes are reviewed in this paper. Membrane lipids with (2)H-labeled acyl chains or polar head groups are studied using (2)H NMR to yield knowledge of their atomistic structures in relation to equilibrium properties. This review demonstrates the principles and applications of solid-state NMR by unifying dipolar and quadrupolar interactions and highlights the unique features offered by solid-state (2)H NMR with experimental illustrations. For randomly oriented multilamellar lipids or aligned membranes, solid-state (2)H NMR enables direct measurement of residual quadrupolar couplings (RQCs) due to individual C-(2)H-labeled segments...
September 14, 2017: Chemical Reviews
Rie Nygaard, Joseph A H Romaniuk, David M Rice, Lynette Cegelski
Solid-state NMR is a powerful tool for quantifying chemical composition and structure in complex assemblies and even whole cells. We employed N{P} REDOR NMR to obtain atomic-level distance propensities in intact 15N-labeled E. coli ribosomes. The experimental REDOR dephasing of shift-resolved lysyl amine nitrogens by phosphorous was comparable to that expected from a calculation of N-P distances involving the lysines included in the crystal structure coordinates. Among the nitrogen contributions to the REDOR spectra, the strongest dephasing emerged from the dipolar couplings to phosphorous involving nitrogen peaks ascribed primarily to rRNA and the weakest dephasing arose from protein amide nitrogens...
September 13, 2017: Journal of Physical Chemistry. B
Denis Lacabanne, Alons Lends, Clément Danis, Britta Kunert, Marie-Laure Fogeron, Vlastimil Jirasko, Claire Chuilon, Lauriane Lecoq, Cédric Orelle, Vincent Chaptal, Pierre Falson, Jean-Michel Jault, Beat H Meier, Anja Böckmann
We here adapted the GRecon method used in electron microscopy studies for membrane protein reconstitution to the needs of solid-state NMR sample preparation. We followed in detail the reconstitution of the ABC transporter BmrA by dialysis as a reference, and established optimal reconstitution conditions using the combined sucrose/cyclodextrin/lipid gradient characterizing GRecon. We established conditions under which quantitative reconstitution of active protein at low lipid-to-protein ratios can be obtained, and also how to upscale these conditions in order to produce adequate amounts for NMR...
September 12, 2017: Journal of Biomolecular NMR
Regine Knitsch, Marie Schneefeld, Kerstin Weitzel, Felicitas Pfeifer
Gas vesicles are proteinaceous, gas-filled nanostructures produced by some bacteria and archaea. The hydrophobic major structural protein GvpA forms the ribbed gas vesicle wall. An in-silico 3D-model of GvpA of the predicted coil-α1-β1-β2-α2-coil structure is available and implies that the two β-chains constitute the hydrophobic interior surface of the gas vesicle wall. To test the importance of individual amino acids in GvpA we performed 85 single substitutions and analysed these variants in Haloferax volcanii ΔA+Amut transformants for their ability to form gas vesicles (Vac(+) phenotype)...
September 12, 2017: Molecular Microbiology
Erika L Buckle, Adrienne Roehrich, Branden Vandermoon, Gary P Drobny
A biomimetic, peptide-mediated approach to inorganic nanostructure formation is of great interest as an alternative to industrial production methods. To investigate the role of peptide structure on silica (SiO2) and titania (TiO2) morphologies, we use the R5 peptide domain derived from the silaffin protein to produce uniform SiO2 and TiO2 nanostructures from the precursor silicic acid and titanium bis(ammonium lactato)dihydroxide, respectively. The resulting biosilica and biotitania nanostructures are characterized using scanning electron microscopy...
September 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Jonathan K Williams, Alexander A Shcherbakov, Jun Wang, Mei Hong
The influenza A and B viruses are the primary cause of seasonal flu epidemics. Common to both viruses is the M2 protein, a homo-tetrameric transmembrane (TM) proton channel that acidifies the virion after endocytosis. Although influenza A M2 (AM2) and B M2 (BM2) are functional analogs, they have little sequence homology, except for a conserved HxxxW motif, which is responsible for proton selectivity and channel gating. Importantly, BM2 contains a second titratable histidine, His27, in the TM domain, which forms a reverse WxxxH motif with the gating tryptophan...
September 11, 2017: Journal of Biological Chemistry
Dominik Kubicki, Daniel Prochowicz, Albert Hofstetter, Shaik M Zakeeruddin, Michael Grätzel, Lyndon Emsley
Hybrid (organic-inorganic) multi-cation lead halide perovskites hold promise for a new generation of easily processable solar cells. Best performing compositions to date are multiple-cation solid alloys of formamidinium (FA), methylammonium (MA), cesium and rubidium lead halides which provide power conversion efficiencies up to around 22%. Here, we elucidate the atomic level nature of Cs and Rb incorporation into the perovskite lattice of FA-based materials. We use 133Cs, 87Rb, 39K, 13C and 14N solid-state MAS NMR to probe microscopic composition of Cs-, Rb-, K-, MA- and FA-containing phases in double-, triple- and quadruple-cation lead halides in bulk and in a thin film...
September 11, 2017: Journal of the American Chemical Society
Vivek S Dave, Hend I Shahin, Susanne R Youngren-Ortiz, Mahavir B Chougule, Rahul V Haware
The density, porosity, breaking force, viscoelastic properties, and the presence or absence of any structural defects or irregularities are important physical-mechanical quality attributes of popular solid dosage forms like tablets. The irregularities associated with these attributes may influence the drug product functionality. Thus, an accurate and efficient characterization of these properties is critical for successful development and manufacturing of a robust tablets. These properties are mainly analyzed and monitored with traditional pharmacopeial and non-pharmacopeial methods...
September 6, 2017: International Journal of Pharmaceutics
Philipp Mühlhäuser, Parvesh Wadhwani, Erik Strandberg, Jochen Bürck, Anne S Ulrich
SSL-25 (SSLLEKGLDGAKKAVGGLGKLGKDA) is one of the shortest peptides present in human sweat and is produced after the proteolytic processing of the parent peptide dermcidin. Both peptides are reported to have antimicrobial function. To determine the structure of SSL-25 in lipid bilayers, a series of (19)F-labeled SSL-25 analogs were synthesized. Circular dichroism (CD) analysis showed that SSL-25 and all of its analogs formed α-helices in the presence of lipid vesicles, thus allowing a detailed analysis via oriented CD and solid-state NMR...
September 6, 2017: Biochimica et Biophysica Acta
Tingting Liu, Xinyuan Hu, Yanfeng Wang, Liyang Meng, Yanan Zhou, Jixiang Zhang, Min Chen, Xiaomei Zhang
With the increase of antibiotic resistances in microorganisms, photodynamic inactivation (PDI) as a clinically proven antibacterial therapy is gaining increasing attention in recent years due to its high efficacy. Herein, we reported two covalent organic frameworks (COFs) materials, namely COFs-Trif-Benz and COF-SDU1, as effective type-II photosensitizers for photodynamic inactivation of bacteria. COFs-Trif-Benz and COF-SDU1 are synthesized through a facile solvothermal reaction between tri-(4-formacylphenoxy)-1,3,5-triazine (trif) and benzidine or p-phenylenediamine with high yield...
July 21, 2017: Journal of Photochemistry and Photobiology. B, Biology
Shameer Pillarisetti, S Maya, S Sathianarayanan, R Jayakumar
Tunable pH and redox responsive polymer was prepared using γ-polyglutamic acid (γ-PGA) with linker 3-mercaptopropionic acid (3-MPA) (γ-PGA_SH) via oxidation to obtain redox responsive disulfide (γ-PGA_SS) backbone and adipic acid dihydrazide (ADH) (γ-PGA_SS_ADH) with hydrazide functional group for pH responsiveness. Further curcumin (Cur) was conjugated through hydrazone bond of the γ-PGA_SS_ADH via Schiff base reaction to obtain (γ-PGA_SS_ADH_Cur). The prepared systems were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Qq-TOF-MS/MS) and Solid state nuclear magnetic resonance (SS NMR) techniques...
August 31, 2017: Colloids and Surfaces. B, Biointerfaces
Lothar Gremer, Daniel Schölzel, Carla Schenk, Elke Reinartz, Jörg Labahn, Raimond B G Ravelli, Markus Tusche, Carmen Lopez-Iglesias, Wolfgang Hoyer, Henrike Heise, Dieter Willbold, Gunnar F Schröder
Amyloids are implicated in neurodegenerative diseases. Fibrillar aggregates of the amyloid-β protein (Aβ) are the main component of the senile plaques found in brains of Alzheimer's disease patients. We present the structure of an Aβ(1-42) fibril composed of two intertwined protofilaments determined by cryoelectron microscopy (cryo-EM) to 4.0 Å resolution, complemented by solid-state nuclear magnetic resonance (NMR) experiments. The backbone of all 42 residues and nearly all sidechains are well resolved in the EM density map, including the entire N terminus, which is part of the cross-β structure resulting in an overall "LS"-shaped topology of individual subunits...
September 7, 2017: Science
Yilei Wu, Jiawang Zhou, Brian T Phelan, Catherine M Mauck, J Fraser Stoddart, Ryan M Young, Michael R Wasielewski
Facile exciton transport within ordered assemblies of π-stacked chromophores is essential for developing molecular photonic and electronic materials. Excimer states having variable charge transfer (CT) character are frequently implicated as promoting or inhibiting exciton mobility in such systems. However, determining the degree of CT character in excimers as a function of their structure has proven challenging. Herein, we report on a series of cyclophanes in which the interplanar distance between two phenyl-extended viologen (<b>ExV<sup>2+</b>) </sup>chromophores is varied systematically using a pair of o-, m-, or p-xylylene (<b>o-</b>, <b>m-</b>, or <b>p-Xy</b>) covalent linkers to produce <b>o-ExBox<sup>4+</sup></b> (3...
September 7, 2017: Journal of the American Chemical Society
Yang Yu, Baltzar Stevensson, Mattias Edén
The short and intermediate range structures of a large series of bioactive borophosphosilicate (BPS) glasses were probed by solid-state nuclear magnetic resonance (NMR) spectroscopy and atomistic molecular dynamics (MD) simulations. Two BPS glass series were designed by gradually substituting SiO₂ by B₂O₃ in the respective phosphosilicate base compositions 24.1Na₂O--23.3CaO--48.6SiO₂--4.0P₂O₅ ("S49") and 24.6Na₂O--26.7CaO--46.1SiO₂--2.6P₂O₅ ("S46"), the latter constituting the "45S5 Bioglass" utilized for bone grafting applications...
September 6, 2017: Journal of Physical Chemistry. B
Lalit Rajput, Manas Banik, Jayasubba Reddy Yarava, Sumy Joseph, Manoj Kumar Pandey, Yusuke Nishiyama, Gautam R Desiraju
There has been significant recent interest in differentiating multicomponent solid forms, such as salts and cocrystals, and, where appropriate, in determining the position of the proton in the X-H⋯A-YX(-)⋯H-A(+)-Y continuum in these systems, owing to the direct relationship of this property to the clinical, regulatory and legal requirements for an active pharmaceutical ingredient (API). In the present study, solid forms of simple cocrystals/salts were investigated by high-field (700 MHz) solid-state NMR (ssNMR) using samples with naturally abundant (15)N nuclei...
July 1, 2017: IUCrJ
David L Bryce
This topical review provides a brief overview of recent developments in NMR crystallography and related NMR approaches to studying the properties of molecular and ionic solids. Areas of complementarity with diffraction-based methods are underscored. These include the study of disordered systems, of dynamic systems, and other selected examples where NMR can provide unique insights. Highlights from the literature as well as recent work from my own group are discussed.
July 1, 2017: IUCrJ
Hiba Hadj Ammar, Sirine Lajili, Nawfel Sakly, Dora Cherif, Christophe Rihouey, Didier Le Cerf, Abderrahman Bouraoui, Hatem Majdoub
Alginates from three genus of Tunisian brown algae were isolated and characterized by size exclusion chromatography and Solid-state NMR spectroscopy. Alginate from Padina pavonica (APP) had the highest molecular weight (Mw) with 147,000g/mol while it was 85,000g/mol for alginate from Cystoseira compressa (ACC) and 58,000g/mol for alginate from Dictyopteris membranaceae (ADM). The mannuronate (M) to guluronate (G) ratios were estimated from spectral deconvolution of the (13)C CP/MAS spectra and the results has shown that all the extracts are mannuronic acid-rich alginates with M/G ratio increased in the order ADM - ACC - APP...
January 15, 2018: Food Chemistry
Akira Naito, Yugo Tasei, Akio Nishimura, Tetsuo Asakura
Alanine oligopeptides provide a key structure of the crystalline domains of the silks from spiders and wild silkworm, and also the sequences included in proteins such as antifreeze proteins and amyloids. In this paper, the local dynamics of alanine oligopeptides, (Ala)3, (Ala)4 and (Ala)6 were examined by high-resolution (13)C solid-state NMR. The (13)C spin-lattice relaxation times (T1's) for the Cβ4 carbons of antiparallel (AP)-β-sheet (Ala)4 significantly prolonged and the correlation time was estimated as 3...
September 5, 2017: Journal of Physical Chemistry. B
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