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Solid state NMR

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https://www.readbyqxmd.com/read/28727439/solid-state-nmr-study-of-the-cicada-wing
#1
John David Gullion, Terry Gullion
Wings of flying insects are part of the cuticle which forms the exoskeleton. The primary molecular components of cuticle are protein, chitin, and lipid. How these components interact with one another to form the exoskeleton is not completely understood. The difficulty in characterizing the cuticle arises because it is insoluble and noncrystalline. These properties severely limit the experimental tools that can be used for molecular characterization. Solid-state nuclear magnetic resonance experiments have been used in the past to characterize the exoskeleton of beetles and have found that chitin and protein make comparable contributions to the molecular matrix...
July 20, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28726925/prospects-for-207-pb-solid-state-nmr-studies-of-lead-tetrel-bonds
#2
Scott A Southern, Dylan Errulat, Jamie M Frost, Bulat Gabidullin, David L Bryce
The feasibility and value of (207)Pb solid-state NMR experiments on compounds featuring lead tetrel bonds is explored. Although the definition remains to be formalized, lead tetrel bonds may be qualitatively described as existing when there is evidence of a net attractive interaction between an electrophilic region associated with lead in a molecular entity and a nucleophilic region in another, or the same, molecular entity. Unambiguous identification of lead tetrel bonds can be challenging due to the hypervalent tendency of lead...
July 20, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28726410/structural-insights-into-the-yersinia-pestis-outer-membrane-protein-ail-in-lipid-bilayers
#3
Samit Kumar Dutta, Yong Yao, Francesca M Marassi
Yersinia pestis the causative agent of plague, is highly pathogenic and poses very high risk to public health. The outer membrane protein Ail (Adhesion invasion locus) is one of the most highly expressed proteins on the cell surface of Y. pestis, and a major target for the development of medical countermeasures. Ail is essential for microbial virulence and is critical for promoting the survival of Y. pestis in serum. Structures of Ail have been determined by X-ray diffraction and solution NMR spectroscopy, but the protein's activity is influenced by the detergents in these samples, underscoring the importance of the surrounding environment for structure-activity studies...
July 20, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28724288/proton-based-structural-analysis-of-a-heptahelical-transmembrane-protein-in-lipid-bilayers
#4
Daniela Lalli, Matthew N Idso, Loren B Andreas, Sunyia Hussain, Naomi Baxter, Songi Han, Bradley F Chmelka, Guido Pintacuda
The structures and properties of membrane proteins in lipid bilayers are expected to closely resemble those in native cell-membrane environments, though have been difficult to elucidate. By performing solid-state NMR measurements at very fast (100 kHz) magic-angle spinning rates and at high (23.5 T) magnetic field, severe sensitivity and resolution challenges are overcome, enabling the atomic-level characterization of membrane proteins in lipid environments. This is demonstrated by extensive (1)H-based resonance assignments of the fully protonated heptahelical membrane protein proteorhodopsin, and the efficient identification of numerous (1)H-(1)H dipolar interactions, which provide distance constraints, inter-residue proximities, relative orientations of secondary structural elements, and protein-cofactor interactions in the hydrophobic transmembrane regions...
July 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28722224/integrating-high-resolution-and-solid-state-magic-angle-spinning-nmr-spectroscopy-and-a-transcriptomic-analysis-of-soybean-tissues-in-response-to-water-deficiency
#5
Isabel D Coutinho, Tiago Bueno Moraes, Liliane Marcia Mertz-Henning, Alexandre Lima Nepomuceno, Willian Giordani, Juliana Marcolino-Gomes, Silvia Santagneli, Luiz Alberto Colnago
INTRODUCTION: Solid-state NMR (SSNMR) spectroscopy methods provide chemical environment and ultrastructural details that are not easily accessible by other non-destructive, high-resolution spectral techniques. High-resolution magic angle spinning (HR-MAS) has been widely used to obtain the metabolic profile of a heterogeneous sample, combining the resolution enhancement provided by MAS in SSNMR with the shimming and locking procedures in liquid-state NMR. OBJECTIVE: In this work, we explored the feasibility of using the HR-MAS and SSNMR techniques to identify metabolic changes in soybean leaves subjected to water-deficient conditions...
July 19, 2017: Phytochemical Analysis: PCA
https://www.readbyqxmd.com/read/28719099/spontaneous-keto-enol-tautomerization-in-the-crystal-lattice-visualized-with-the-help-of-water-encapsulated-in-hydrophilic-reservoirs
#6
Marta K Dudek, Ewelina Wielgus, Piotr Paluch, Marek Potrzebowski
Keto-enol tautomerism in the solid phase is a process that is particularly difficult to follow. In this work we demonstrate how it can be done by introducing deuterium into the crystal lattice of organic compounds, which tend to form hydrates. In our studies we explored H-D exchange in the crystals stored in contact with deuterium oxide vapors. Employing barbituric acid (BA) and (+)-catechin (CAT) as model samples, by means of advanced solid-state NMR and mass spectrometry, we revealed that not only OH and NH protons of these chemicals undergo exchange to deuterium in a crystal lattice, but also usually immobile protons, i...
July 18, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28715619/properties-of-water-confined-in-periodic-mesoporous-organosilicas-nanoimprinting-the-local-structure
#7
Michael Fröba, J Benedikt Mietner, Felix J Brieler, Young Joo Lee
The properties of materials confined in porous media are important in scientific and technological aspects. Topology, size and surface polarity of the pores play a critical role in the confinement effects, however, knowledge regarding the guest-pore interface structure is still lacking. Here, we show that the molecular mobility of water confined in periodic mesoporous organosilicas (PMOs) is influenced by the polarity of the organic moiety. Multidimensional solid state NMR directly probes the spatial arrangement of water inside the pores, demonstrating that water interacts either with only the silicate layer or with both silicate and organic layers depending on the alternating surface polarity...
July 17, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28715169/fabrication-of-biocompatible-functional-and-transparent-hybrid-films-based-on-silk-fibroin-and-epoxy-silane-for-biophotonics
#8
Robson Rosa da Silva, Mauricio Cavicchioli, Lais Rocalho de Lima, Caio Gomide Otoni, Hernane da Silva Barud, Silvia Helena Santagneli, Agnieszka Tercjak, André Capaldo Amaral, Renata Aquino Carvalho, Sidney José Lima Ribeiro
In this work we explored the fabrication of flexible and transparent hybrids of silk fibroin and epoxy modified siloxane for photonic applications. It is well known that regenerated silk fibroin (SF) solutions can form free-standing films with high transparency. Although SF has a restricted number of chemically reactive side groups, the main issues of as-casted pristine SF films regard the high solubility into aqueous media, brittleness, and low thermal stability. The design of SF films with enhanced functionality but yet highly transparent triggers new opportunities on broader range of applications in biophotonics...
July 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28715023/amorphous-boron-nanorod-as-an-anode-material-for-lithium-ion-batteries-at-room-temperature
#9
Changjian Deng, Miu Lun Lau, Heather M Barkholtz, Haiping Xu, Riley Parrish, Meiyue Olivia Xu, Tao Xu, Yuzi Liu, Hao Wang, Justin G Connell, Kassiopeia A Smith, Hui Xiong
We report an amorphous boron nanorod anode material for lithium-ion batteries prepared through smelting non-toxic boron oxide in liquid lithium. Boron in theory can provide capacity as high as 3099 mA h g(-1) by alloying with Li to form B4Li5. However, experimental studies of the boron anode have been rarely reported for room temperature lithium-ion batteries. Among the reported studies the electrochemical activity and cycling performance of the bulk crystalline boron anode material are poor at room temperature...
July 17, 2017: Nanoscale
https://www.readbyqxmd.com/read/28714510/radical-reactions-of-diamine-bis-phenolate-vanadium-iii-complexes-solid-state-binding-of-o2-to-form-a-vanadium-v-peroxo-complex
#10
Sónia Barroso, Ana M Coelho, Pedro Adão, Maria José Calhorda, Ana M Martins
[VCl3(THF)3] reacted with the sodium salt of a tripodal diamine bisphenolate ligand precursor Na2L2 to give a paramagnetic d(2) complex [V(L2)Cl] (2). The reaction of 2 with oxygen is strongly dependent on the experimental conditions, affording [VO(L2)Cl] (6) or [V(η(2)-O2)(L2)Cl] (7). The formation of 7 involves the direct addition of O2 to V(iii) in the solid state with oxidation to V(v) without significantly disturbing the structure of 2. DFT calculations showed that compound 7 is an intermediate in the formation of 6 from 2...
July 17, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28714233/bioinspired-size-tunable-self-assembly-of-polymer-lipid-bilayer-nanodiscs
#11
Thirupathi Ravula, Sudheer Ramadugu, Giacomo Di Mauro, Ayyalusamy Ramamoorthy
Polymer-based nanodiscs are valuable tools in biomedical research that can offer a detergent-free solubilization of membrane proteins maintaining their native lipid environment. Here, we introduce a novel ~1.6 kDa SMA-based polymer with styrene:maleic acid moieties that can form nanodiscs containing a planar lipid bilayer which are useful to reconstitute membrane proteins for structural and functional studies. The physicochemical properties and the mechanism of formation of polymer-based nanodiscs are characterized by light scattering, NMR, FT-IR, and TEM imaging experiments...
July 16, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28711848/long-term-litter-manipulation-alters-soil-organic-matter-turnover-in-a-temperate-deciduous-forest
#12
Jun-Jian Wang, Oliva Pisani, Lisa H Lin, Olivia O Y Lun, Richard D Bowden, Kate Lajtha, André J Simpson, Myrna J Simpson
Understanding soil organic matter (OM) biogeochemistry at the molecular-level is essential for assessing potential impacts from management practices and climate change on shifts in soil carbon storage. Biomarker analyses and nuclear magnetic resonance (NMR) spectroscopy were used in an ongoing detrital input and removal treatment experiment in a temperate deciduous forest in Pennsylvania, USA, to examine how above- and below-ground plant inputs control soil OM quantity and quality at the molecular-level. From plant material to surface soils, the free acyclic lipids and cutin, suberin, and lignin biomarkers were preferentially retained over free sugars and free cyclic lipids...
July 13, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28710349/lipid-driven-nanodomains-in-giant-lipid-vesicles-are-fluid-and-disordered
#13
Alena Koukalová, Mariana Amaro, Gokcan Aydogan, Gerhard Gröbner, Philip T F Williamson, Ilya Mikhalyov, Martin Hof, Radek Šachl
It is a fundamental question in cell biology and biophysics whether sphingomyelin (SM)- and cholesterol (Chol)- driven nanodomains exist in living cells and in model membranes. Biophysical studies on model membranes revealed SM and Chol driven micrometer-sized liquid-ordered domains. Although the existence of such microdomains has not been proven for the plasma membrane, such lipid mixtures have been often used as a model system for 'rafts'. On the other hand, recent super resolution and single molecule results indicate that the plasma membrane might organize into nanocompartments...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28709996/applications-of-solid-state-nmr-to-membrane-proteins
#14
REVIEW
Vladimir Ladizhansky
Membrane proteins mediate flow of molecules, signals, and energy between cells and intracellular compartments. Understanding membrane protein function requires a detailed understanding of the structural and dynamic properties involved. Lipid bilayers provide a native-like environment for structure-function investigations of membrane proteins. In this review we give a general discourse on the recent progress in the field of solid-state NMR of membrane proteins. Solid-state NMR is a variation of NMR spectroscopy that is applicable to molecular systems with restricted mobility, such as high molecular weight proteins and protein complexes, supramolecular assemblies, or membrane proteins in a phospholipid environment...
July 11, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28705502/synthesis-and-characterization-of-hydrogel-films-of-carboxymethyl-tamarind-gum-using-citric-acid
#15
Kailas K Mali, Shashikant C Dhawale, Remeth J Dias
The objective of this study was to synthesize and characterize citric acid crosslinked carboxymethyl tamarind gum (CMTG) hydrogels films. The hydrogel films were characterized by Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, solid state (13)C-nuclear magnetic resonance ((13)C NMR) spectroscopy and differential scanning calorimeter (DSC). The prepared hydrogel films were evaluated for the carboxyl content and swelling ratio. The model drug moxifloxacin hydrochloride was loaded into hydrogels films and drug release was studied at pH 7...
July 10, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28699757/solvent-driven-dynamical-cross-over-in-the-phenylalanine-side-chain-from-the-hydrophobic-core-of-amyloid-fibrils-detected-by-2-h-nmr-relaxation
#16
Liliya Vugmeyster, Dmitry Ostrovsky, Gina L Hoatson, Wei Qiang, Isaac Benjamin Falconer
Aromatic residues are important markers of dynamical changes in proteins' hydrophobic cores. In this work we investigated the dynamics of the F19 side-chain in the core of amyloid fibrils across a wide temperature range of 300 to 140 K. We utilized solid-state 2H NMR relaxation to demonstrate the presence of a solvent-driven dynamical cross-over between different motional regimes, often also referred to as the dynamical transition. In particular, the dynamics are dominated by small-angle fluctuations at low temperatures and by π-flips of the aromatic ring at high temperatures...
July 12, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28699734/solution-and-solid-state-nmr-structural-investigations-of-the-antimicrobial-designer-peptide-gl13k-in-membranes
#17
Nicole Harmouche, Christopher Aisenbrey, Fernando Porcelli, Youlin Xia, Sarah E D Nelson, Xi Chen, Jesus Raya, Louic S Vermeer, Conrado Aparicio, Gianluigi Veglia, Sven-Ulrik Gorr, Burkhard Bechinger
The antimicrobial peptide GL13K encompasses 13 amino acid residues and has been designed and optimized from the salivary protein BPIFA2 to exhibit potent bacteriocidal and anti-biofilm activity against Gram-negative and Gram-positive bacteria as well as anti-lipopolysaccharide activity in vitro and in vivo. Here, the peptide was analyzed in a variety of membrane environments by CD spectroscopy and by high resolution multidimensional solution NMR spectroscopy. Whereas in the absence of membranes a random coil conformation predominates, the peptide adopts a helical structure from residues 5 to 11 in the presence of DPC micelles...
July 12, 2017: Biochemistry
https://www.readbyqxmd.com/read/28698492/the-application-of-redor-nmr-to-understand-the-conformation-of-epothilone-b
#18
Jae-Ho Lee, Moon-Su Kim, Hyo Won Lee, Ihl-Young C Lee, Hyun Kyoung Kim, Nam Doo Kim, SangGap Lee, Hwajeong Seo, Younkee Paik
The structural information of small therapeutic compounds complexed in biological matrices is important for drug developments. However, structural studies on ligands bound to such a large and dynamic system as microtubules are still challenging. This article reports an application of the solid-state NMR technique to investigating the bioactive conformation of epothilone B, a microtubule stabilizing agent, whose analog ixabepilone was approved by the U.S. Food and Drug Administration (FDA) as an anticancer drug...
July 9, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28697887/molecular-origins-of-the-compatibility-between-glycosaminoglycans-and-a%C3%AE-40-amyloid-fibrils
#19
Katie L Stewart, Eleri Hughes, Edwin A Yates, David A Middleton, Sheena E Radford
The Aβ peptide forms extracellular plaques associated with Alzheimer's disease. In addition to protein fibrils, amyloid plaques also contain non-proteinaceous components, including glycosaminoglycans (GAGs). We have shown previously that the GAG low molecular weight heparin (LMWH) binds to Aβ40 fibrils with a three-fold-symmetric (3Q) morphology with higher affinity than Aβ40 fibrils in alternative structures, Aβ42 fibrils, or amyloid fibrils formed from other sequences. Solid-state NMR (SSNMR) analysis of the GAG-3Q fibril complex revealed an interaction site at the corners of the 3Q fibril structure, but the origin of the binding specificity remained obscure...
July 8, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28692804/dynamic-nuclear-polarization-efficiency-increased-by-very-fast-magic-angle-spinning
#20
Sachin R Chaudhari, Dorothea Wisser, Arthur C Pinon, Pierrick Berruyer, David Gajan, Paul Tordo, Olivier Ouari, Christian Reiter, Frank Engelke, Christophe Copéret, Moreno Lelli, Anne Lesage, Lyndon Emsley
Dynamic Nuclear Polarization has recently emerged as a tool to enhance the sensitivity of solid-state NMR experiments. However, so far high enhancements (>100) are limited to relatively low magnetic fields, and DNP at fields higher than 9.4 T significantly drops in efficiency. Here we report solid-state Overhauser effect DNP enhancements of over 100 at 18.8 T. This is achieved through the unexpected discovery that enhancements increase rapidly with increasing magic angle spinning rates. The measurements are made using 1,3-bisdiphenylene-2-phenylallyl (BDPA) dissolved in ortho-terphenyl (OTP) at 40 kHz MAS...
July 10, 2017: Journal of the American Chemical Society
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