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Antoine Loquet, James Tolchard, Melanie Berbon, Denis Martinez, Birgit Habenstein
Supramolecular protein assemblies play fundamental roles in biological processes ranging from host-pathogen interaction, viral infection to the propagation of neurodegenerative disorders. Such assemblies consist in multiple protein subunits organized in a non-covalent way to form large macromolecular objects that can execute a variety of cellular functions or cause detrimental consequences. Atomic insights into the assembly mechanisms and the functioning of those macromolecular assemblies remain often scarce since their inherent insolubility and non-crystallinity often drastically reduces the quality of the data obtained from most techniques used in structural biology, such as X-ray crystallography and solution Nuclear Magnetic Resonance (NMR)...
September 17, 2017: Journal of Visualized Experiments: JoVE
Katsuaki Suzuki, Shosei Kubo, Fabien Aussenac, Frank Engelke, Tatsuya Fukushima, Hironori Kaji
Molecular orientation in amorphous organic semiconducting thin film devices is an important issue affecting device performances. However, to date it has not been possible to analyze the "distribution" of the orientations. Although solid-state NMR (ssNMR) can provide information on the distribution of molecular orientations, the technique is limited because of the small amounts of sample in the devices and the low sensitivity of ssNMR. Here, we report the first application of dynamic nuclear polarization enhanced ssNMR (DNP-ssNMR) to orientational analysis of amorphous phenyldi(pyren-1-yl)phosphine oxide (POPy2)...
October 9, 2017: Angewandte Chemie
Nicholas J Grantham, Joel Wurman-Rodrich, Oliver M Terrett, Jan J Lyczakowski, Katherine Stott, Dinu Iuga, Thomas J Simmons, Mylene Durand-Tardif, Steven P Brown, Ray Dupree, Marta Busse-Wicher, Paul Dupree
Xylan and cellulose are abundant polysaccharides in vascular plants and essential for secondary cell wall strength. Acetate or glucuronic acid decorations are exclusively found on even-numbered residues in most of the glucuronoxylan polymer. It has been proposed that this even-specific positioning of the decorations might permit docking of xylan onto the hydrophilic face of a cellulose microfibril (1-3) . Consequently, xylan adopts a flattened ribbon-like twofold screw conformation when bound to cellulose in the cell wall (4) ...
October 9, 2017: Nature Plants
Elisana Afonso de Moura, Márcio Vinícius Cahino Terto, Elisângela Afonso de Moura Mendonça, José Valdilânio Virgulino Procópio, Vicente Carlos de O Costa, José Maria Barbosa Filho, Stanley Juan Chavez Gutierrez, Josean Fechine Tavares, Rui Oliveira Macedo, Marcelo Sobral da Silva
Riparin I is an alkamide with potential anxiolytic activity in preclinical studies. The characterization and understanding of solid-state properties play an importance role in drug development. For this work, the solid state of five riparin I batches (RIP-1, RIP-2, RIP-3, RIP-4, and RIP-5), obtained by the same synthesis process, were characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), DSC-photovisual, Thermogravimetry (TG), Fourier Transform Infrared (FTIR), Pyrolysis (Pyr-GC/MS), X-ray Powder Diffraction (PXRD), and Solid-State Nuclear Magnetic Resonance (ssNMR) techniques...
October 9, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
M Naiserová, K Kubová, J Vysloužil, S Pavloková, D Vetchý, M Urbanová, J Brus, J Vysloužil, P Kulich
Burst drug release is often considered a negative phenomenon resulting in unexpected toxicity or tissue irritation. Optimal release of a highly soluble active pharmaceutical ingredient (API) from hypromellose (HPMC) matrices is technologically impossible; therefore, a combination of polymers is required for burst effect reduction. Promising variant could be seen in combination of HPMC and insoluble Eudragits(®) as water dispersions. These can be applied only on API/insoluble filler mixture as over-wetting prevention...
October 2, 2017: AAPS PharmSciTech
Giovanna Bruni, Vittorio Berbenni, Lauretta Maggi, Piercarlo Mustarelli, Valeria Friuli, Chiara Ferrara, Francesca Pardi, Federica Castagna, Alessandro Girella, Chiara Milanese, Amedeo Marini
OBJECTIVE: To improve the pharmaceutical behaviour of the oral antidiabetic agent gliclazide through the synthesis of multicomponent crystals with tromethamine. METHODS: Multicomponent crystals were prepared by solvent evaporation method, kneading and combining mechanical and thermal activation. DSC, FT-IR spectroscopy, X-ray diffraction, SEM-EDS and SSNMR were used to investigate their formation. Measurements of solubility and dissolution rate were carried out for the pharmaceutical characterization...
September 28, 2017: Drug Development and Industrial Pharmacy
Ahmad B Albadarin, Catherine B Potter, Mark T Davis, Javed Iqbal, Sachin Korde, Sudhir Pagire, Anant Paradkar, Gavin Walker
The aim of this study was to evaluate a novel combination of hydroxypropyl methylcellulose phthalate (HPMCP-HP-50) and Soluplus(®) polymers for enhanced physicochemical stability and solubility of the produced amorphous solid dispersions (ASDs). This was achieved using hot melt extrusion (HME) to convert the crystalline active pharmaceutical ingredient (API) into a more soluble amorphous form within the ternary systems. Itraconazole (ITZ), a Biopharmaceutics Classification System class II (BCS II) API, was selected as the model drug...
September 18, 2017: International Journal of Pharmaceutics
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 25, 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
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
Clara Correa-Soto, Niraj S Trasi, Paul D Schmitt, Yongchao Su, Zhen Liu, Elise Miller, Narayan Variankaval, Patrick J Marsac, Garth J Simpson, Lynne S Taylor
Various techniques have been used to detect crystallization in amorphous solid dispersions (ASD). However, most of these techniques do not enable the detection of very low levels of crystallinity (<1%). The aim of the current study was to compare the sensitivity of second harmonic generation (SHG) microscopy with powder X-ray diffraction (XRPD) in detecting the presence of crystals in low drug loading amorphous solid dispersions. Amorphous solid dispersions of the poorly water soluble compounds, flutamide (FTM, 15wt...
August 24, 2017: Journal of Pharmaceutical and Biomedical Analysis
Ary R Ferreira, José P Rino
Solid-state nuclear magnetic resonance (ssNMR) experimental (27)Al metallic shifts reported in the literature for bulk metallic glasses (BMGs) were revisited in the light of state-of-the-art atomistic simulations. In a consistent way, the Gauge-Including Projector Augmented-Wave (GIPAW) method was applied in conjunction with classical molecular dynamics (CMD). A series of Zr-Cu-Al alloys with low Al concentrations were selected as case study systems, for which realistic CMD derived structural models were used for a short- and medium-range order mining...
August 24, 2017: Scientific Reports
Ahmad Ziaee, Ahmad B Albadarin, Luis Padrela, Alexandra Faucher, Emmet O'Reilly, Gavin Walker
A design of experiment (DoE) approach was used to investigate the critical formulation and processing parameters in spray drying ternary amorphous solid dispersions (ASDs) of ibuprofen. A range of 16 formulations of ibuprofen, HPMCP-HP55 and Kollidon VA 64 were spray dried. Statistical analysis revealed the interrelation of various spray drying process conditions and formulation factors, namely solution feed rate, inlet temperature, Active Pharmaceutical Ingredient (API)/excipients ratio and dichloromethane (DCM)/methanol (MeOH) ratio...
November 2017: European Journal of Pharmaceutics and Biopharmaceutics
Peter Werhun, David L Bryce
Despite the significance of nickel compounds, NMR spectroscopy of the active nickel isotope (61)Ni remains a largely unexplored field. While nickel(0) compounds have been studied by (61)Ni NMR in solution, solid-state experiments have been limited to Knight shift studies of nickel metal and nickel intermetallics. In conjunction with an NMR study of their ligands and (61)Ni relativistic computations, the first (61)Ni solid-state NMR (SSNMR) spectra of diamagnetic compounds are reported here. Specifically, bis(1,5-cyclooctadiene)nickel(0) [Ni(cod)2], tetrakis(triphenylphosphite)nickel(0) [Ni[P(OPh)3]4], and tetrakis(triphenylphosphine)nickel(0) [Ni(PPh3)4] were studied...
August 3, 2017: Inorganic Chemistry
Lucile Senicourt, Luminita Duma, Vassilios Papadopoulos, Jean-Jacques Lacapere
Structural studies of membrane proteins (MP) in a native or native-like environment remain a challenge. X-ray crystallography of three-dimensional crystals of MP in lipids and cryo-electron microscopy of two-dimensional crystals also in lipids have given atomic structures of several MP. Recent developments of solid-state NMR (ssNMR) provided structural data of MP in lipids and should give access to the dynamic behavior of MP's in a native-like environment. Preparation of samples for ssNMR is not trivial with overexpressed proteins since purified recombinant MP have to be reincorporated in proteoliposomes and concentrated in the small volume of the rotor used for ssNMR studies...
2017: Methods in Molecular Biology
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
Wenzhe Pang, Jie Lv, Shuang Du, Jiaojiao Wang, Jing Wang, Yanli Zeng
In the present study, a new coamorphous phase (CAP) of bioactive herbal ingredient curcumin (CUR) with high solubilitythe was screened with pharmaceutically acceptable coformers. Besides, to provide basic information for the best practice of physiological and pharmaceutical preparations of CUR-based CAP, the interaction between CUR-based CAP and bovine serum albumin (BSA) was studied at the molecular level in this paper. CAP of CUR and piperazine with molar ratio of 1:2 was prepared by EtOH-assisted grinding...
August 3, 2017: Molecular Pharmaceutics
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 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...
August 4, 2017: Journal of Molecular Biology
Manuri Brahmayya, Shenghong A Dai, Shing-Yi Suen
Acid catalysts facilitate many chemical reactions. Sulfonated reduced grapheneoxide (rGOPhSO3H) has shown to be an encouraging solid acid catalyst because of its efficiency, cost-effectiveness and safety of use. In this study, we prepared the rGOPhSO3H nano acid catalyst, with the introduction of aromatic sulfonic acid radicals onto GO by fractional removal of oxygenated functions. It was thoroughly characterized by FT-IR, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, energy dispersive spectroscopy (EDS) and solid state (13)C MAS NMR (SSNMR)...
July 5, 2017: Scientific Reports
Łukasz Szeleszczuk, Dariusz Maciej Pisklak, Monika Zielińska-Pisklak, Iwona Wawer
Diosmin, a flavone glycoside frequently used in therapy of various veins diseases in monohydrate form, exhibits poor solubility in water and low bioavailability. Due to the fact that the anhydrous forms of drugs generally have better bioavailability than the corresponding hydrates, the aim of this study was to analyze the conversion of diosmin monohydrate (DSNM) to anhydrous diosmin (DSNA) that occurs upon heating. The mechanism of this transformation was examined as well as advanced structural studies of each form were performed using 13C CP/MAS SSNMR, DSC, FT-IR and PXRD techniques...
June 27, 2017: International Journal of Pharmaceutics
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