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chemical shift

Shobini Jayaraman, Jose Luis Sánchez-Quesada, Olga Gursky
Lipids in the body are transported via lipoproteins that are nanoparticles comprised of lipids and amphipathic proteins termed apolipoproteins. This family of lipid surface-binding proteins is over-represented in human amyloid diseases. In particular, all major proteins of high-density lipoproteins (HDL), including apoA-I, apoA-II and serum amyloid A, can cause systemic amyloidoses in humans upon protein mutations, post-translational modifications or overproduction. Here, we begin to explore how the HDL lipid composition influences amyloid deposition by apoA-I and related proteins...
October 18, 2016: Biochimica et Biophysica Acta
Koichi Hattori, Yi Yin
We investigate novel transport phenomena in a chiral fluid originated from an interplay between a vorticity and strong magnetic field, which induces a redistribution of vector charges in the system and an axial current along the magnetic field. The corresponding transport coefficients are obtained from an energy-shift argument for the chiral fermions in the lowest Landau level due to a spin-vorticity coupling and also from diagrammatic computations on the basis of the linear response theory. Based on consistent results from both methods, we observe that the transport coefficients are proportional to the anomaly coefficient and are independent of temperature and chemical potential...
October 7, 2016: Physical Review Letters
Yan-Ming Wang, Jian-Qiang Zhao, Jun-Li Yang, Yan-Duo Tao, Li-Juan Mei, Yan-Ping Shi
A new flavonoid, along with 16 known ones, was separated from the aerial parts of Asterothamnus centrali-asiaticus. Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D NMR techniques and HRESIMS. To confirm the structure of the new compound, computational prediction of its (13)C chemical shifts was performed. All of the 17 flavonoids were reported from A. centrali-asiaticus for the first time. In addition, all flavonoids were evaluated for their antioxidant and α-glucosidase inhibitory activities...
October 21, 2016: Natural Product Research
Hongwei Yao, Myungwoon Lee, Shu Y Liao, Mei Hong
The fusion peptide (FP) and transmembrane domain (TMD) of viral fusion proteins play important roles during virus-cell membrane fusion, by inducing membrane curvature and transient dehydration. The structure of the water-soluble ectodomain of viral fusion proteins has been extensively studied crystallographically, but the structures of the FP and TMD bound to phospholipid membranes are not well understood. We recently investigated the conformations and lipid interactions of the separate FP and TMD peptides of the parainfluenza virus 5 (PIV5) fusion protein F using solid-state NMR...
October 21, 2016: Biochemistry
Anurag Mishra, Giorgio Pariani, Thomas Oerther, Markus Schwaiger, Gil Gregor Westmeyer
We introduce hyperpolarizable (13)C-labelled probes that identify multiple biologically important divalent metals via metal-specific chemical shifts. These features enable NMR measurements of calcium concentrations in human serum in the presence of magnesium. In addition, signal enhancement through Dynamic Nuclear Polarization (DNP) increases the sensitivity of metal detection to afford measuring micromolar concentrations of calcium as well as simultaneous multi-metal detection by chemical shift imaging. The hyperpolarizable (13)C-MRI sensors presented here enable sensitive NMR measurements and MR imaging of multiple divalent metals in opaque biological samples...
October 21, 2016: Analytical Chemistry
Zhe Zhang, Bing Zhang, Ming Li, Xue Liang, Xiaodong Chen, Renyuan Liu, Xin Zhang, Hua Guo
PURPOSE: To report a diffusion imaging technique insensitive to off-resonance artifacts and motion-induced ghost artifacts using mulitshot Cartesian turbo spin-echo (TSE) acquisition and iterative POCS-based reconstruction of multiplexed sensitivity encoded magnetic resonance imaging (MRI) (POCSMUSE) for phase correction. MATERIALS AND METHODS: Phase insensitive diffusion preparation was used to deal with the violation of the Carr-Purcell-Meiboom-Gill (CPMG) conditions of TSE diffusion-weighted imaging (DWI), followed by a mulitshot Cartesian TSE readout for data acquisition...
October 20, 2016: Journal of Magnetic Resonance Imaging: JMRI
Berrin Serdar, Stephen Brindley, Greg Dooley, John Volckens, Elizabeth Juarez-Colunga, Ryan Gan
BACKGROUND: Roofers are at increased risk for various malignancies and their occupational exposures to polycyclic aromatic hydrocarbons (PAHs) have been considered as important risk factors. The overall goal of this project was to investigate the usefulness of phosphorylated histone H2AX (γH2AX) as a short-term biomarker of DNA damage among roofers. METHODS: Blood, urine, and dermal wipe samples were collected from 20 roofers who work with hot asphalt before and after 6 h of work on Monday and Thursday of the same week (4 sampling periods)...
October 20, 2016: Environmental Health: a Global Access Science Source
Christoph Göbl, Moritz Resch, Madeleine Strickland, Christoph Hartlmüller, Martin Viertler, Nico Tjandra, Tobias Madl
The study of intrinsically disordered proteins (IDPs) by NMR often suffers from highly overlapped resonances that prevent unambiguous chemical-shift assignments, and data analysis that relies on well-separated resonances. We present a covalent paramagnetic lanthanide-binding tag (LBT) for increasing the chemical-shift dispersion and facilitating the chemical-shift assignment of challenging, repeat-containing IDPs. Linkage of the DOTA-based LBT to a cysteine residue induces pseudo-contact shifts (PCS) for resonances more than 20 residues from the spin-labeling site...
October 20, 2016: Angewandte Chemie
Xiangao Zhang, Mingzhen Shao, Xiaoqi Zeng
In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance peaks via strengthening the mutual coupling of the cavities. The research results show that with the increase of the symmetry breaking in the structure, the number of Fano resonances increase accordingly...
October 18, 2016: Sensors
Debojit Bhattacharya, Suranjan Shil, Anirban Misra, Laimutis Bytautas, Douglas J Klein
Here we study a set of novel magnetic organic molecular species with different halide ions (fluoride, chloride, bromide) absorbed ~2Å above or below the center of an aromatic π-ring in an m-aminyl diradical. Focus is on the nature of anion-π interaction and its impact on magnetic properties, specifically on magnetic anisotropy and on intramolecular magnetic exchange coupling. In the development of single molecule magnets, magnetic anisotropy is considered to be the most influential factor. A new insight regarding the magnetic anisotropy which determines the barrier height for relaxation of magnetization of m-aminyl diradical-derived anionic complexes is obtained from calculations of the axial Zero-Field-Splitting (ZFS) parameter D...
October 20, 2016: Journal of Physical Chemistry. A
Le Zhang, Alex Burant, Andrew McCallister, Victor Zhao, Karl M Koshlap, Simone Degan, Michael Antonacci, Rosa Tamara Branca
PURPOSE: To investigate the temperature dependence of the resonance frequency of lipid-dissolved xenon (LDX) and to assess the accuracy of LDX-based MR thermometry. METHODS: The chemical shift temperature dependence of water protons, methylene protons, and LDX was measured from samples containing tissues with varying fat contents using a high-resolution NMR spectrometer. LDX results were then used to acquire relative and absolute temperature maps in vivo and the results were compared with PRF-based MR thermometry...
October 19, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Bice S Martincigh, Moses A Ollengo
The photostabilizing ability of grape seed extract on three common sunscreen absorbers: 2-ethylhexyl-p-methoxcinnamate (EHMC), benzophenone-3 (BP3) and tert-butylmethoxy dibenzoylmethane (BMDBM), was investigated. Samples were exposed to simulated solar radiation and monitored by spectrophotometric and chromatographic methods. The chemical composition of the grape seed extract was determined by GC-MS and HPLC-MS and the major secondary metabolites were found to be epicatechin and catechin. Exposure of the extract to UV radiation increased the UV absorption capacity of the extract...
October 19, 2016: Photochemistry and Photobiology
Donato Belmonte, Carlo Gatti, Giulio Armando Ottonello, Pascal Richet, Marino Vetuschi Zuccolini
Thermodynamic and thermophysical properties of Na2SiO3 in the Cmc21 structural state are computed ab-initio using the hybrid B3LYP density functional method. The static properties at the athermal limit are first evaluated through a symmetry-preserving relaxation procedure. The thermodynamic properties that depend on vibrational frequencies viz, heat capacities, thermal expansion, thermal derivative of the bulk modulus, thermal correction to internal energy, enthalpy, Gibbs free energy, are then computed in the framework of quasi-harmonic approximation...
October 19, 2016: Journal of Physical Chemistry. A
Mukul R Gupta, Alok Kumar, Naveen K Khare
Two new compounds 1 (Methyl 26-di-deoxy-6-methyl-β-D-allohexopyranoside) and 3 (3, 11, 12, 20 tetra-O-acetyl-pregn-5-ene-14β-ol) have been isolated from the chloroform-soluble extract of the whole plant of Marsdenia roylei (family: Asclepiadaceae) and their structures were determined by 1D, 2D NMR and ESI-MS as well as by chemical modification. We have calculated the molecular geometries, local reactivity descriptors by the density functional theory with B3LYP functional with basis set 6-311G+(d,2p) of 1, 3 and 4 (deacylated 3)...
October 18, 2016: Natural Product Research
Yohei Okada, Masae Sugai, Kazuhiro Chiba
Fluorophores with emission wavelengths that shift depending on their hydrogen-bonding microenvironment in water would be fascinating tools for the study of biological events. Herein, we describe the design and synthesis of a series of water-soluble solvatochromic fluorophores, 2,5-bis(oligoethylene glycol)oxybenzaldehydes (8-11) and 2,5-bis(oligoethylene glycol)oxy-1,4-dibenzaldehydes (14-17), based on a push-pull strategy. Unlike typical examples in this class of fluorophores, the fluorescence properties of these compounds are independent of solvent polarity and become fluorescent upon intermolecular hydrogen-bonding, exhibiting high quantum yields (up to φ = 0...
October 18, 2016: Journal of Organic Chemistry
Andresa H Betti, Camila B Antonio, Thais E T Pompeu, Thaise S Martins, Vivian Herzfeldt, Eveline D Stolz, Carlos A M Fraga, Eliezer Barreiro, François Noël, Stela M K Rates
Aiming to identify new antipsychotic lead-compounds, our group has been working on the design and synthesis of new N-phenylpiperazine derivatives. Here, we characterized LASSBio-1422 as a pharmacological prototype of this chemical series. Adult male Wistar rats and CF1 mice were used for in-vitro and in-vivo assays, respectively. LASSBio-1422 [1 and 5 mg/kg, postoperatively (p.o.)] inhibited apomorphine-induced climbing as well as ketamine-induced hyperlocomotion (1 and 5 mg/kg, p.o.), animal models predictive of efficacy on positive symptoms...
October 13, 2016: Behavioural Pharmacology
Gregory J O Beran, Joshua D Hartman, Yonaton N Heit
Molecular crystals occur widely in pharmaceuticals, foods, explosives, organic semiconductors, and many other applications. Thanks to substantial progress in electronic structure modeling of molecular crystals, attention is now shifting from basic crystal structure prediction and lattice energy modeling toward the accurate prediction of experimentally observable properties at finite temperatures and pressures. This Account discusses how fragment-based electronic structure methods can be used to model a variety of experimentally relevant molecular crystal properties...
October 18, 2016: Accounts of Chemical Research
Boran Lee, Byung Gyu Park, Wansang Cho, Ho Yong Lee, András Olasz, Chun-Hsing Chen, Seung Bum Park, Dongwhan Lee
A series of air-stable boron complexes 1-5 were prepared by using N-aryl iminopyrrolide ligands. Designed as minimalist structural mimics of the privileged BODIPY motif, these new BOIMPY (BOron complexes of IMinoPYrrolide ligands) fluorophores feature low molecular symmetry that promotes emission from CT-type excited states with large Stokes shifts and little self-quenching. Through comparative studies on the homologous set of compounds 1-4, we have confirmed that a delicate interplay between conformational twisting and donor-acceptor interaction dictates the mechanism of de-excitation, which responds sensitively to solvent polarity as well as protonation states...
October 18, 2016: Chemistry: a European Journal
Roger Duncan Amos, Rika Kobayashi
We revisit the NMR shielding constants of a model 10-residue peptide system by investigating the use of Jensen's NMR specialised basis sets and locally dense basis sets within the fragmentation molecular orbital scheme. It is found that this procedure can reproduce the shielding constants of a full calculation at only a fraction of the cost. Strategies for choosing fragments and complications that need to be considered within the method are discussed extensively.
October 18, 2016: Journal of Physical Chemistry. A
Zujun Xu, Mengmeng Pang, Changwang Li, Baocun Zhu
Recently, growing attention has been paid to the detection of hydrazine (NH2 NH2 ) because of its important roles in industrial chemical and high toxicity to human beings. Herein, we have constructed a new colorimetric and far-red fluorescent probe containing a receptor of 4-bromobutanoate to selectively detect hydrazine. The probe could detect hydrazine quantitatively in the range of 40-500 μM with the detection limit of 2.9 μM. In addition, the probe could monitor hydrazine by the ratiometric method with a large (185 nm) red-shifted absorption spectrum, and the color changes from yellow to blue make it as a 'naked-eye' indicator for hydrazine...
October 18, 2016: Luminescence: the Journal of Biological and Chemical Luminescence
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