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Solid state NMR

Bhanu Pratap Prajapati, Rahul Kumar Suryawanshi, Sarika Agrawal, Manasi Ghosh, Naveen Kango
The aim of this work was to characterize cellulase from Aspergillus tubingensis NKBP-55 for generation of fermentable sugars from agricultural residues. The strain produced high titres of cellulase (750 U/gds) on copra meal in solid state fermentation (SSF). The enzyme preparation also showed hemicellulolytic activities (U/gds) viz. endo-mannanase (1023), endo-xylanase (167), β-glucosidase (72) and α-galactosidase (54). Zymography revealed presence of six cellulases, six mannanases and one β-glucosidase...
December 2, 2017: Bioresource Technology
Gavin R Kiel, Sajan Chandresh Patel, Patrick W Smith, Daniel S Levine, T Don Tilley
A divergent synthetic strategy allowed access to several members of a new class of helicenes, the "expanded helicenes", which are composed of alternating linearly- and angularly-fused rings. The strategy is based on a threefold, partially intermolecular [2+2+n] (n = 1 or 2) cycloaddition with substrates containing three diyne units. Investigation of aggregation behavior, both in solution and the solid state, revealed that one of these compounds forms an unusual homochiral, π-stacked dimer via an equilibrium that is slow on the NMR timescale...
December 7, 2017: Journal of the American Chemical Society
Yi Hu, Pascal Kienlen-Campard, Tzu-Chun Tang, Florian Perrin, Rémi Opsomer, Marie Decock, Xiaoshu Pan, Jean-Noel Octave, Stefan N Constantinescu, Steven O Smith
Familial mutations in C99 can increase the total level of the soluble Aβ peptides produced by proteolysis, as well as the Aβ42/Aβ40 ratio, both of which are linked to the progression of Alzheimer's disease. We show that the extracellular sequence of C99 forms β-sheet structure upon interaction with membrane bilayers. Mutations that disrupt this structure result in a significant increase in Aβ production and, in specific cases, result in an increase in the amount of Aβ42 relative to Aβ40. Fourier transform infrared and solid-state NMR spectroscopic studies reveal a central β-hairpin within the extracellular sequence comprising Y10-E11-V12 and L17-V18-F19 connected by a loop involving H13-H14-Q15...
December 7, 2017: Scientific Reports
Anne E Harman-Ware, Renee M Happs, Brian H Davison, Mark F Davis
Background: Lignin dehydrogenation polymers (DHPs) are polymers generated from phenolic precursors for the purpose of studying lignin structure and polymerization processes. Methods: Here, DHPs were synthesized using a Zutropfverfahren method with horseradish peroxidase and three lignin monomers, sinapyl (S), coumaryl (H), and coniferyl (G) alcohols, in the presence of hydrogen peroxide. The H monomer was reacted with G and a 1:1 molar mixture of S:G monomers at H molar compositions of 0, 5, 10, and 20 mol% to study how the presence of the H monomer affected the structure and composition of the recovered polymers...
2017: Biotechnology for Biofuels
Eva Meirovitch, Zhichun Liang, Jack H Freed
We report on a new approach to the analysis of dynamic NMR lineshapes from polycrystalline (i.e., macroscopically disordered) samples in the presence of Magic Angle Spinning (MAS). This is an application of the Stochastic Liouville Equation developed by Freed and co-workers for treating restricted (i.e., microscopically ordered) motions. The 2H nucleus in an internally-mobile C-CD3 moiety serves as a prototype probe. The acronym is 2H/MOMD/MAS, where MOMD stands for "microscopic-order-macroscopic-disorder." The key elements describing internal motions - their type, the local spatial restrictions, and related features of local geometry - are treated in MOMD generally, within their rigorous three-dimensional tensorial requirements...
November 21, 2017: Solid State Nuclear Magnetic Resonance
Alexander A Pavlov, Gleb L Denisov, Mikhail A Kiskin, Yulia V Nelyubina, Valentin V Novikov
Spin transitions in spin-crossover compounds are now routinely studied in the solid state by magnetometry; however, only a few methods exist for studies in solution. The currently used Evans method, which relies on NMR spectroscopy to measure the magnetic susceptibility, requires the availability of a very pure sample of the paramagnetic compound and its exact concentration. To overcome these limitations, we propose an alternative NMR-based technique for evaluating spin-state populations by only using the chemical shifts of a spin-crossover compound; those can be routinely obtained for a solution that contains unknown impurities and paramagnetic admixtures or is contaminated otherwise...
December 5, 2017: Inorganic Chemistry
Peng Yang, Hui Li, Tian Ma, Fadi Haso, Tianbo Liu, Linyuan Fan, Zhengguo Lin, Changwen Hu, Ulrich Kortz
The SrII-centered 12-palladate(II) open-cube {SrPd12(OAc)3} has been systematically evolved by substitution of the three acetate ligands by a library of saturated carboxylic acids with increasing chain lengths leading to four novel polyoxopalladates(II) with the formula [SrPd12O6(OH)3(PhAsO3)6(L)3]4- (SrPd12L3, L = CnH2n+1COO, n = 2 to 5). These first examples of surfactant-type polyoxopalladates with a hydrophilic metal-oxo unit and three hydrophobic alkyl chains were characterized in the solid state (single-crystal XRD, FT-IR, TGA), in solution (1H, 13C NMR), and in the gas phase (ESI-MS)...
December 4, 2017: Chemistry: a European Journal
Masaya Matsuki, Teppei Yamada, Nobuhiro Yasuda, Shun Dekura, Hiroshi Kitagawa, Nobuo Kimizuka
Tetraethylammonium-d20 d-10-camphorsulfonate was newly synthesized. It has three solid phases, whose crystal structure was determined by a single crystal X-ray analysis. XRD analysis revealed a phase transition from nonpolar P21212 to polar space group P21 with increasing temperature. The dynamics of the d-10-camphorsulfonate anion and the tetraethylammo-nium-d20 cation was investigated by variable-temperature (VT) solid-state NMR spectroscopy of 1H and 2H nuclei, respec-tively. The anion showed swing motion in high-temperature phases, which is in good agreement with the disorder ob-served in XRD analysis...
December 4, 2017: Journal of the American Chemical Society
Su-Jin Kang, Yasuto Todokoro, Suyeon Bak, Toshiharu Suzuki, Masasuke Yoshida, Toshimichi Fujiwara, Hideo Akutsu
FoF1-ATP synthase catalyzes ATP hydrolysis/synthesis coupled with a transmembrane H+ translocation in membranes. The Fo c-subunit ring plays a major role in this reaction. We have developed an assignment strategy for solid-state 13C NMR (ssNMR) signals of the Fo c-subunit ring of thermophilic Bacillus PS3 (TFo c-ring, 72 residues), carrying one of the basic folds of membrane proteins. In a ssNMR spectrum of uniformly 13C-labeled sample, the signal overlap has been a major bottleneck because most amino acid residues are hydrophobic...
December 2, 2017: Journal of Biomolecular NMR
Denis Lacabanne, Beat H Meier, Anja Böckmann
Selective isotope labeling is central in NMR experiments and often allows to push the limits on the systems investigated. It has the advantage to supply additional resolution by diminishing the number of signals in the spectra. This is particularly interesting when dealing with the large protein systems which are currently becoming accessible to solid-state NMR studies. Isotope labeled proteins for NMR experiments are most often expressed in E. coli systems, where bacteria are grown in minimal media supplemented with 15NH4Cl and 13C-glucose as sole source of nitrogen and carbon...
December 2, 2017: Journal of Biomolecular NMR
Cecilia Pinto, Deni Mance, Manon Julien, Mark Daniels, Markus Weingarth, Marc Baldus
Significant progress has been made in obtaining a structural insight into the assembly of the β-barrel assembly machinery complex (BAM). These crystallography and electron microscopy studies used detergent as a membrane mimetic and revealed structural variations in the central domain, BamA, as well as the lipoprotein BamC. We have used cellular solid-state NMR spectroscopy to examine the entire BamABCDE complex in native outer membranes and obtained data on the BamCDE subcomplex in outer membranes, in addition to synthetic bilayers...
November 29, 2017: Journal of Structural Biology
Abdelghani Hassainia, Hamid Satha, Sami Boufi
Chitin was isolated from three main fruit body parts of the Agaricusbisporus mushroom, i.e. pileus, stipes and gills. Chitin was extracted by alkaline treatment of A. bisporus fruit body parts in 1M NaOH at 80°C for 2h.The lyophilized fruit bodies were examined by SEM and exhibited a porous structure that is favorable to polysaccharide extraction. A mild extraction method was adopted to limit the degradation of chitin. The highest extraction yield of chitin was obtained for stipes (7.4% of dry weight). For pileus and gills, yields of chitin were 6...
November 29, 2017: International Journal of Biological Macromolecules
Davide Balestri, Yoann Roux, Monica Mattarozzi, Claudio Mucchino, Laurent Heux, Deborah Brazzolotto, Vincent Artero, Carole Duboc, Paolo Pelagatti, Luciano Marchiò, Marcello Gennari
In the quest for new, efficient, and noble-metal-free H2-evolution catalysts, hydrogenase enzymes are a source of inspiration. Here, we describe the development of a new hybrid material based on a structural and functional [NiFe]-hydrogenase model complex (NiFe) incorporated into the Zr-based MOF PCN-777. The bulk NiFe@PCN-777 material was synthesized by simple encapsulation. Characterization by solid-state NMR and IR spectroscopy, SEM-EDX, ICP-OES, and gas adsorption confirmed the inclusion of the guest. FTO-supported thin films of the NiFe@PCN-777 composite were obtained by electrophoretic deposition of the bulk material and characterized by SEM-EDX, ICP-OES, and cyclic voltammetry...
December 1, 2017: Inorganic Chemistry
Lauren N Grant, Balazs Pinter, Brian C Manor, Hangjoerg Gruetzmacher, Daniel J Mindiola
The first example of the OCPPCO ligand, diisophosphaethynolate, is reported via reductive coupling of an Sc-OCP precursor. Upon reduction with KC8, isolation of the dinuclear complex, namely [K(OEt2)]2[(nacnac)Sc(OAr)]2(OCPPCO), is observed, leading to a unique motif [OCPPCO]4-, stabilized by two scandium centers. We report detailed NMR spectra of all complexes as well as IR and single crystal X-ray studies to fully elucidate the nature of these complexes in solution as well the solid state. Theory is combined to probe the electronic structure and orbitals responsible for the bonding interactions in Sc-OCPPCO-Sc skeleton but also compared to the linear mode observed in the precursor...
November 29, 2017: Angewandte Chemie
Li Zhao, Arthur C Pinon, Lyndon Emsley, Aaron J Rossini
Solid-state NMR has become a valuable tool for the characterization of both pure and formulated active pharmaceutical ingredients (APIs). However, NMR generally suffers from poor sensitivity that often restricts NMR experiments to nuclei with favorable properties, concentrated samples and acquisition of 1D NMR spectra. Here we review how dynamic nuclear polarization (DNP) can be applied to routinely enhance the sensitivity of solid-state NMR experiments by one to two orders of magnitude for both pure and formulated APIs...
November 28, 2017: Magnetic Resonance in Chemistry: MRC
R Li, R Rajan, W C V Wong, D G Reid, M J Duer, V J Somovilla, N Martinez-Saez, G J L Bernardes, R Hayward, C M Shanahan
Non-enzymatic glycation of extracellular matrix with (U-13C5)-d-ribose-5-phosphate (R5P), enables in situ 2D ssNMR identification of many deleterious protein modifications and crosslinks, including previously unreported oxalamido and hemiaminal (CH3-CH(OH)NHR) substructures. Changes in charged residue proportions and distribution may be as important as crosslinking in provoking and understanding harmful tissue changes.
December 1, 2017: Chemical Communications: Chem Comm
Eric C Y Tam, David C Apperley, J David Smith, Martyn P Coles, J Robin Fulton
The reactivity of tin and lead phosphanido complexes with chalogens is reported. The addition of sulfur to [(BDI)MPCy2] (M = Sn, Pb; BDI = CH{(CH3)CN-2,6-iPr2C6H3}2) results in the formation of phosphinodithioates [(BDI)MSP(S)Cy2] regardless of the conditions; however, when selenium is added to [(BDI)MPCy2], a selenium insertion product, phosphinoselenoite [(BDI)MSePCy2], can be isolated. This compound readily reacts with additional selenium to form the phosphinodiselenoate complex [(BDI)MSeP(Se)Cy2]. In contrast, the addition of selenium to [(BDI)SnP(SiMe3)2] results in the formation of the heavy ether [(BDI)SnSeSiMe3]...
November 30, 2017: Inorganic Chemistry
Tengfei Li, Wei Zhang, Wei Chen, Haralampos N Miras, Yu-Fei Song
In recent years, great attention has been dedicated to the development of heterogeneous base catalysts providing a green and sustainable process in benign aqueous media. Herein, the ionic liquid modified layered double hydroxide (LDH) based catalysts of LDH-IL-Cn (n = 4, 8, 12) were prepared by adopting an exfoliation/assembly strategy, in which the ionic liquids (ILs) were covalently anchored onto the surface of LDH layers. The resulting LDH-IL-Cn were characterized by FT-IR, solid-state 13C NMR, 29Si CP/MAS NMR, 27Al-MAS NMR, XRD, TG-DTA, BET, XPS, SEM, CO2-TPD, contact angle experiments, etc...
November 29, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Shrawan Baghel, Helen Cathcart, Niall J O'Reilly
In this study, the dissolution behaviour of dipyridamole (DPM) and cinnarizine (CNZ) spray-dried amorphous solid dispersions (ASDs) using polyvinyl pyrrolidone (PVP) and polyacrylic acid (PAA) as a carrier matrix were evaluated and compared. The drug concentrations achieved from the dissolution of PVP and PAA solid dispersions were significantly greater than the equilibrium solubility of crystalline DPM and CNZ in phosphate buffer pH 6.8 (PBS 6.8). The maximum drug concentration achieved by dissolution of PVP and PAA solid dispersions did not exceed the theoretically calculated apparent solubility of amorphous DPM and CNZ...
November 25, 2017: International Journal of Pharmaceutics
A A Colbourne, T W Blythe, R Barua, S Lovett, J Mitchell, A J Sederman, L F Gladden
Nuclear magnetic resonance rheology (Rheo-NMR) is a valuable tool for studying the transport of suspended non-colloidal particles, important in many commercial processes. The Rheo-NMR imaging technique directly and quantitatively measures fluid displacement as a function of radial position. However, the high field magnets typically used in these experiments are unsuitable for the industrial environment and significantly hinder the measurement of shear stress. We introduce a low field Rheo-NMR instrument (1H resonance frequency of 10...
November 21, 2017: Journal of Magnetic Resonance
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