Read by QxMD icon Read


Brian K Yoo, Yiling Xiao, Dan McElheny, Yoshitaka Ishii
Cross-seeding of misfolded amyloid proteins is believed to induce cross-species infection of prion diseases. In sporadic Alzheimer's disease (AD), misfolding of 42-residue β-amyloid (Aβ) is widely considered to trigger amyloid plaque deposition. Despite increasing evidence that misfolded Aβ mimics prions, interactions of misfolded 42-residue Aβ42 with more abundant 40-residue Aβ40 in AD are elusive. This study presents in-vitro evidence that a heterozygous E22G pathogenic ("Arctic") mutation of Aβ40 can enhance misfolding of Aβ via cross-seeding from wild-type (WT) Aβ42 fibril...
February 9, 2018: Journal of the American Chemical Society
Conor M Haney, E James Petersson
The neuronal protein α-synuclein (αS) plays a key role in Parkinson's disease, forming inclusions termed Lewy bodies and Lewy neurites. Recent improvements in cryo-electron diffraction and solid state NMR (ssNMR) have led to the elucidation of the structures of peptides derived from the αS fibril core and full-length human αS in fibrils. Despite the valuable insight offered by these methods, there are still several questions about the structures' relevance to pathological aggregates. Herein, we present fluorescence data collected in vitro under the conditions which fibrils are typically assembled...
January 9, 2018: Chemical Communications: Chem Comm
Silvina Orlandi, Josefina Priotti, Hermínio P Diogo, Dario Leonardi, Claudio J Salomon, Teresa G Nunes
Praziquantel (PZQ) is the recommended, effective, and safe treatment against all forms of schistosomiasis. Solid dispersions (SDs) in water-soluble polymers have been reported to increase solubility and bioavailability of poorly water-soluble drugs like PZQ, generally due to the amorphous form stabilization. In this work, poloxamer (PLX) 237 and poly(vinylpyrrolidone) (PVP) K30 were evaluated as potential carriers to revert PZQ crystallization. Binary and ternary SDs were prepared by the solvent evaporation method...
January 8, 2018: AAPS PharmSciTech
Yufei Yang, Shenlin Wang
The structures of RNAs, which play critical roles in various biological processes, provide important clues and insights into the biological functions of these molecules. However, RNA structure determination remains a challenging topic. In recent years, magic-angle-spinning solid-state nuclear magnetic resonance (MAS SSNMR) has emerged as an alternative technique for structural and dynamic characterization of RNA. MAS SSNMR has been successfully applied to provide atomic-level structural information about several RNA molecules and RNA-protein complexes...
December 25, 2017: Chemistry: a European Journal
Songlin Wang, T Gopinath, Gianluigi Veglia
Oriented sample solid-state NMR (OS-ssNMR) spectroscopy is uniquely suited to determine membrane protein topology at the atomic resolution in liquid crystalline bilayers under physiological temperature. However, the inherent low sensitivity of this technique has hindered the throughput of multidimensional experiments necessary for resonance assignments and structure determination. In this work, we show that doping membrane protein bicelle preparations with paramagnetic ion chelated lipids and exploiting paramagnetic relaxation effects it is possible to accelerate the acquisition of both 2D and 3D multidimensional experiments with significant saving in time...
December 21, 2017: Methods: a Companion to Methods in Enzymology
Tetyana I Levchenko, Bryan E G Lucier, John F Corrigan, Yining Huang
Systematic 111Cd solid-state (SS) NMR experiments were performed to correlate X-ray crystallographic data with SSNMR parameters for a set of CdS-based materials, varying from molecular crystals of small complexes [Cd(SPh)4]2- and [Cd4(SPh)10]2- to superlattices of large monodisperse clusters [Cd54S32(SPh)48(dmf)4]4- and 1.9 nm CdS. Methodical data analysis allowed for assigning individual resonances or resonance groups to particular types of cadmium sites residing in different chemical and/or crystallographic environments...
December 15, 2017: Inorganic Chemistry
Yoshitaka Ishii, Ayesha Wickramasinghe, Isamu Matsuda, Yuki Endo, Yuji Ishii, Yusuke Nishiyama, Takahiro Nemoto, Takayuki Kamihara
Proton-detected solid-state NMR (SSNMR) spectroscopy has attracted much attention due to its excellent sensitivity and effectiveness in the analysis of trace amounts of amyloid proteins and other important biological systems. In this perspective article, we present the recent sensitivity limit of 1H-detected SSNMR using "ultra-fast" magic-angle spinning (MAS) at a spinning rate (νR) of 80-100 kHz. It was demonstrated that the high sensitivity of 1H-detected SSNMR at νR of 100 kHz and fast recycling using the paramagnetic-assisted condensed data collection (PACC) approach permitted "super-fast" collection of 1H-detected 2D protein SSNMR...
November 28, 2017: Journal of Magnetic Resonance
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
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
T Gopinath, Sarah E D Nelson, Gianluigi Veglia
Magic angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy is emerging as a unique method for the atomic resolution structure determination of native membrane proteins in lipid bilayers. Although 13C-detected ssNMR experiments continue to play a major role, recent technological developments have made it possible to carry out 1H-detected experiments, boosting both sensitivity and resolution. Here, we describe a new set of 1H-detected hybrid pulse sequences that combine through-bond and through-space correlation elements into single experiments, enabling the simultaneous detection of rigid and dynamic domains of membrane proteins...
December 2017: Journal of Magnetic Resonance
Boris Itin, Ivan V Sergeyev
Solid-state NMR (SSNMR) is a powerful tool for the elucidation of structure and dynamics in biological macromolecules. Over the years, SSNMR spectroscopists have developed an array of techniques enabling the measurement of internuclear correlations, distances, and torsional angles; these have been applied to the study of a number of biological systems that are difficult to study by X-ray crystallography and solution NMR, including key biological targets such as membrane proteins and amyloid fibrils. Applications of SSNMR to other topic areas, including materials science, pharmaceuticals, and small molecules, have also flourished in recent years...
2018: Methods in Molecular Biology
Siddarth Narasimhan, Deni Mance, Cecilia Pinto, Markus Weingarth, Alexandre M J J Bonvin, Marc Baldus
Solid-state NMR (ssNMR) can provide structural information at the most detailed level and, at the same time, is applicable in highly heterogeneous and complex molecular environments. In the last few years, ssNMR has made significant progress in uncovering structure and dynamics of proteins in their native cellular environments [1-4]. Additionally, ssNMR has proven to be useful in studying large biomolecular complexes as well as membrane proteins at the atomic level [5]. In such studies, innovative labeling schemes have become a powerful approach to tackle spectral crowding...
2018: Methods in Molecular Biology
Omry Morag, Nikolaos G Sgourakis, Gili Abramov, Amir Goldbourt
Filamentous bacteriophages are elongated semi-flexible viruses that infect bacteria. They consist of a circular single-stranded DNA (ssDNA) wrapped by a capsid consisting of thousands of copies of a major coat protein subunit. Given the increasing number of discovered phages and the existence of only a handful of structures, the development of methods for phage structure determination is valuable for biophysics and structural virology. In recent years, we developed and applied techniques to elucidate the 3D atomic-resolution structures of intact bacteriophages using experimental magic-angle spinning (MAS) solid-state NMR data...
2018: Methods in Molecular Biology
Łukasz Szeleszczuk, Ewa Jurczak, Monika Zielińska-Pisklak, Jakub Harwacki, Dariusz Maciej Pisklak
The application of various techniques (FT-IR, PXRD, ssNMR) in the analysis of solid dosage forms with low concentration of an API (17-β-estradiol hemihydrate, EBHH) was tested. PXRD analysis of Estrofem Mite tablets (EMT) confirmed the presence of the main crystalline excipient, α-lactose monohydrate. In the PXRD pattern of EMT the strong background from polycrystalline excipients, i.e. hydroxypropylmethylcellulose and corn starch was observed. FT-IR spectra were characterized by the broad peaks in the 3000-3600cm(-1) region of the OH stretching modes coming from multiple hydrogen bonds that are present in the structures of the excipients (α-lactose monohydrate, corn starch) and API...
November 6, 2017: Journal of Pharmaceutical and Biomedical Analysis
Kelsey A Collier, Suvrajit Sengupta, Catalina A Espinosa, John E Kelly, Jessica I Kelz, Rachel W Martin
Extensive deuteration is frequently used in solid-state NMR studies of biomolecules because it dramatically reduces both homonuclear ((1)H-(1)H) and heteronuclear ((1)H-(13)C and (1)H-(15)N) dipolar interactions. This approach greatly improves resolution, enables low-power rf decoupling, and facilitates (1)H-detected experiments even in rigid solids at moderate MAS rates. However, the resolution enhancement is obtained at some cost due the reduced abundance of protons available for polarization transfer. Although deuterium is a useful spin-1 NMR nucleus, in typical experiments the deuterons are not directly utilized because the available probes are usually triple-tuned to (1)H,(13)C and (15)N...
October 12, 2017: Journal of Magnetic Resonance
Libor Kobera, Jan Rohlicek, Jiri Czernek, Sabina Abbrent, Magda Streckova, Tibor Sopcak, Jiri Brus
Framework materials, both metal-organic frameworks (MOFs) and inorganic frameworks (zeolites), are porous systems with regular structures that provide valuable properties suitable for sorption, catalysis, molecular sieving, etc. Herein, we present an efficient, experimental/computational strategy allowing for the detailed characterization of a polycrystalline MOF system, ZBIF-1, with two integrated unit cells on the atomic-resolution level. Although high-resolution 1H, 11B, 13C and 15N MAS NMR spectra provided valuable structural information on the co-existence of two distinct asymmetric units in the investigated system, the utilized NMR crystallography approach combining XRPD, ssNMR and DFT calculations allowed us to firmly define the exact structure of the secondary crystalline phase and, furthermore, to resolve the mutual interconnectivity of the two crystalline frameworks...
October 19, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Patrick C A van der Wel
The aggregation of proteins and peptides into a variety of insoluble, and often non-native, aggregated states plays a central role in many devastating diseases. Analogous processes undermine the efficacy of polypeptide-based biological pharmaceuticals, but are also being leveraged in the design of biologically inspired self-assembling materials. This Trends article surveys the essential contributions made by recent solid-state NMR (ssNMR) studies to our understanding of the structural features of polypeptide aggregates, and how such findings are informing our thinking about the molecular mechanisms of misfolding and aggregation...
October 4, 2017: Solid State Nuclear Magnetic Resonance
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 performance. However, to date it has not been possible to analyze the "distribution" of the orientations. Although solid-state NMR (ssNMR) spectroscopy can provide information on the "distribution" of molecular orientations, the technique is limited because of the small amount of sample in the device and the low sensitivity of ssNMR. Here, we report the first application of dynamic nuclear polarization enhanced ssNMR (DNP-ssNMR) spectroscopy for the 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
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"