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https://www.readbyqxmd.com/read/28538145/nmr-analysis-of-amide-hydrogen-exchange-rates-in-a-pentapeptide-repeat-protein-from-a-%C3%A2-thaliana
#1
Shenyuan Xu, Shuisong Ni, Michael A Kennedy
At2g44920 from Arabidopsis thaliana is a pentapeptide-repeat protein (PRP) composed of 25 repeats capped by N- and C-terminal α-helices. PRP structures are dominated by four-sided right-handed β-helices typically consisting of mixtures of type II and type IV β-turns. PRPs adopt repeated five-residue (Rfr) folds with an Rfr consensus sequence (STAV)(D/N)(L/F)(S/T/R)(X). Unlike other PRPs, At2g44920 consists exclusively of type II β-turns. At2g44920 is predicted to be located in the thylakoid lumen although its biochemical function remains unknown...
May 23, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28538102/effects-of-wet-blending-on-detection-of-melamine-in-spray-dried-lactose
#2
Betsy Jean Yakes, Marti M Bergana, Peter F Scholl, Magdi M Mossoba, Sanjeewa R Karunathilaka, Luke K Ackerman, Jason D Holton, Boyan Gao, Jeffrey C Moore
During the development of rapid screening methods to detect economic adulteration, spray-dried milk powders prepared by dissolving melamine in liquid milk exhibited an unexpected loss of characteristic melamine features in the NIR and Raman spectra. To further characterize this "wet-blending" phenomenon, spray-dried melamine and lactose samples were produced as a simplified model and investigated by near-infrared spectroscopy, Raman spectroscopy, 1H NMR, and DART-FTMS. In contrast to dry-blended samples, characteristic melamine bands in NIR and Raman spectra disappeared or shifted in wet-blended lactose-melamine samples...
May 24, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28537738/a-peptoid-square-helix-via-synergistic-control-of-backbone-dihedral-angles
#3
Benjamin Craig Gorske, Emily M Mumford, Charles G Gerrity, Imelda Ko
The continued expansion of the fields of macromolecular chemistry and nanoscience has motivated the development of new secondary structures that can serve as architectural elements of innovative materials, molecular machines, biological probes, and even commercial medicines. Synthetic foldamers are particularly attractive systems for developing such elements because they are specifically designed to facilitate synthetic manipulation and functional diversity. However, relatively few predictive design principles exist that permit both rational and modular control of foldamer secondary structure, while maintaining the capacity for facile diversification of displayed functionality...
May 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28537726/hot-spotting-with-thermal-scanning-a-ligand-and-structure-independent-assessment-of-target-ligandability
#4
Molly Chilton, Ben Clennell, Fredrik Edfeldt, Stefan Geschwindner
Evaluating the ligandability of a protein target is a key component when defining hit-finding strategies or to prioritize amongst drug targets. Computational as well as biophysical approaches based on nuclear magnetic resonance (NMR) fragment screening are powerful approaches, but suffer from specific constraints that limit their usage. Here, we demonstrate the applicability of high-throughput thermal scanning (HTTS) as a simple and generic biophysical fragment screening method to reproduce assessments from NMR-based screening...
May 24, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28537719/synthesis-and-characterization-of-the-lithium-rich-phosphidosilicates-li10si2p6-and-li3si3p7
#5
Henrik Eickhoff, Lorenzo Toffoletti, Wilhelm Klein, Gabriele Raudaschl-Sieber, Thomas F Fässler
The lithium phosphidosilicates Li10Si2P6 and Li3Si3P7 are obtained by high-temperature reactions of the elements or including binary Li-P precursors. Li10Si2P6 (P21/n, Z = 2, a = 7.2051(4) Å, b = 6.5808(4) Å, c = 11.6405(7) Å, β = 90.580(4)°) features edge-sharing SiP4 double tetrahedra forming [Si2P6](10-) units with a crystal structure isotypic to Na10Si2P6 and Na10Ge2P6. Li3Si3P7 (P21/m, Z = 2, a = 6.3356(4) Å, b = 7.2198(4) Å, c = 10.6176(6) Å, β = 102.941(6)°) crystallizes in a new structure type, wherein SiP4 tetrahedra are linked via common vertices and which are further connected by polyphosphide chains to form unique ∞(2)[Si3P7](3-) double layers...
May 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28537712/proton-control-of-the-lanthanoid-single-ion-magnet-behavior-of-a-double-decker-complex-with-an-indolenine-substituted-annulene-ligand
#6
Zhifu Liang, Marko Damjanović, Mritunjoy Kamila, Goulven Cosquer, Brian K Breedlove, Markus Enders, Masahiro Yamashita
Two double-decker complexes with annulene ligands functionalized with indolenine groups were synthesized and characterized. The position of the proton acting as a counterion on one of the four indolenine nitrogen atoms was determined by using DFT calculations. Deprotonation and protonation of the complex induced by adding a base and an acid, respectively, were monitored by using NMR spectroscopy. Moreover, a correlation among the degree of protonation of the complex, the opening of the hysteresis, and the slow relaxation time is discussed...
May 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28537705/hypoxia-responsive-19-f-mri-probes-with-improved-redox-properties-and-biocompatibility
#7
Da Xie, Seyong Kim, Vikraant Kohli, Arnab Banerjee, Meng Yu, José S Enriquez, Jeffrey J Luci, Emily L Que
(19)F magnetic resonance imaging (MRI), an emerging modality in biomedical imaging, has shown promise for in vitro and in vivo preclinical studies. Here we present a series of fluorinated Cu(II)ATSM derivatives for potential use as (19)F magnetic resonance agents for sensing cellular hypoxia. The synthesized complexes feature a hypoxia-targeting Cu(2+) coordination core, nine equivalent fluorine atoms connected via a variable-length poly(ethylene glycol) linker. Introduction of the fluorine moiety maintains the planar coordination geometry of the Cu(2+) center, while the linker length modulates the Cu(2+/+) reduction potential, (19)F NMR relaxation properties, and lipophilicity...
May 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28535423/chromatographic-separation-and-detection-methods-of-aloe-arborescens-miller-constituents-a-systematic-review
#8
REVIEW
Jilan A Nazeam, Haidy A Gad, Hala M El-Hefnawy, Abdel-Naser B Singab
Aloe arborescens Miller (Family Asphodelaceae) is a member of genus Aloe, which is used in traditional medicine to cure various diseases. The extracts of the plant have been reported to possess anticancer, immunomodulator, antidiabetic, anti-inflammatory and antioxidant activities. The phytochemical investigations have revealed diverse chemical constituents, including phenolics [anthraquinones, anthrones, pyrones, chromones and coumarins], polysaccharides [arborans [(1-4) linked glucomannans, polysaccharide (A, B and C): (A: a linear (1-6)-O-α-glucan, B: a branching (1-2)-O-l-arabinose with (1-2)-O-d-galactose linkages and C: (1-4)-O-β-mannan with 18% acetyl group)]], glycoproteins and carboxypeptidase enzyme...
April 29, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28535421/differentiation-of-crataegus-spp-guided-by-nuclear-magnetic-resonance-spectrometry-with-chemometric-analyses
#9
Jensen A Lund, Paula N Brown, Paul R Shipley
For compliance with US Current Good Manufacturing Practice regulations for dietary supplements, manufacturers must provide identity of source plant material. Despite the popularity of hawthorn as a dietary supplement, relatively little is known about the comparative phytochemistry of different hawthorn species, and in particular North American hawthorns. The combination of NMR spectrometry with chemometric analyses offers an innovative approach to differentiating hawthorn species and exploring the phytochemistry...
May 20, 2017: Phytochemistry
https://www.readbyqxmd.com/read/28535345/natural-predominance-of-abscisic-acid-in-pongammia-pinnata-karanj-honey-contributed-to-its-strong-antimutagenicity
#10
Sudhanshu Saxena, Jyoti Tripathi, Suchandra Chatterjee, Satyendra Gautam
Various samples of raw (unprocessed) floral honey collected from different geographical locations of India were assayed for its antimutagenicity against ethyl methanesulfonate in E. coli MG1655 cells through rifampicin resistance assay. A monofloral honey ('Pongammia pinnata', local name 'Karanj') displayed maximum antimutagenicity (78.0 ± 1.7; P≤0.05). Solid phase extraction (using amberlite XAD-2 resin) followed by HPLC resulted into different peaks displaying varying antimutagenicity. Peak at retention time (Rt) 27...
May 23, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28535337/overall-structural-model-of-ns5a-protein-from-hepatitis-c-virus-and-modulation-by-mutations-confering-resistance-of-virus-replication-to-cyclosporin-a
#11
Aurelie Badillo, Veronique Brechot, Stephane Sarrazin, François-Xavier Cantrelle, Frederic Delolme, Marie-Laure Fogeron, Jennifer Molle, Roland Montserret, Anja Bockmann, Ralf Bartenschlager, Volker Lohmann, Guy Lippens, Sylvie Ricard-Blum, Xavier Hanoulle, Francois Penin
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a RNA-binding phosphoprotein composed of a N-terminal membrane anchor (AH), a structured domain 1 (D1) and two intrinsically disordered domains (D2 and D3). The knowledge of the functional architecture of this multifunctional protein remains limited. We report here that NS5A-D1D2D3 produced in a wheat germ cell-free system is obtained under a highly phosphorylated state. Its NMR analysis revealed that these phosphorylations do not change the disordered nature of D2 and D3 domains but increase the number of conformers due to partial phosphorylations...
May 23, 2017: Biochemistry
https://www.readbyqxmd.com/read/28535056/solid-state-nmr-structure-based-inhibitor-design-to-achieve-selective-inhibition-of-the-parallel-in-register-%C3%AE-sheet-versus-antiparallel-iowa-mutant-%C3%AE-amyloid-fibrils
#12
Qinghui Cheng, Wei Qiang
Solid-state nuclear magnetic resonance (ssNMR) spectroscopy has been widely applied to characterize the high-resolution structures of β-amyloid (Aβ) fibrils. While these structures provide crucial molecular insights on the deposition of amyloid plaques in Alzheimer's diseases (AD), ssNMR structures have been rarely used so far as basis for designing inhibitors. It remains a challenge because the ssNMR-based Aβ fibrils structures were usually obtained with sparsely-isotope-labeled peptides with limited experimental constraints, where the structural models, especially the side-chain coordinates showed restricted precision...
May 23, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28535042/dudawalamides-a-d-antiparasitic-cyclic-depsipeptides-from-the-marine-cyanobacterium-moorea-producens
#13
Jehad Almaliti, Karla L Malloy, Evgenia Glukhov, Carmenza Spadafora, Marcelino Gutiérrez, William H Gerwick
A family of 2,2-dimethyl-3-hydroxy-7-octynoic acid (Dhoya)-containing cyclic depsipeptides, named dudawalamides A-D (1-4), was isolated from a Papua New Guinean field collection of the cyanobacterium Moorea producens using bioassay-guided and spectroscopic approaches. The planar structures of dudawalamides A-D were determined by a combination of 1D and 2D NMR experiments and MS analysis, whereas the absolute configurations were determined by X-ray crystallography, modified Marfey's analysis, chiral-phase GCMS, and chiral-phase HPLC...
May 23, 2017: Journal of Natural Products
https://www.readbyqxmd.com/read/28534843/three-new-abietane-type-diterpenoids-from-callicarpa-macrophylla-vahl
#14
Zhen-Hui Wang, Chao Niu, De-Jun Zhou, Ji-Chuan Kong, Wen-Kui Zhang
Three new abietane-type diterpenoids, named callicapoic acid M3 (1), callicapoic acid M4 (2) and callicapoic acid M5 (3), were isolated from the Callicarpa macrophylla Vahl. Their structures were established by spectroscopic techniques (IR, UV, MS, 1D and 2D NMR). All the isolated three compounds were evaluated for inhibitory activity on NO production in LPS-activated RAW 264.7 macrophage cells by using MTT assays. Compounds 1, 2 and 3 showed potent inhibitory activity, with inhibition rates of 34.47-40.13%...
May 19, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28534807/lobophorin-k-a-new-natural-product-with-cytotoxic-activity-produced-by-streptomyces-sp-m-207-associated-with-the-deep-sea-coral-lophelia-pertusa
#15
Alfredo F Braña, Aida Sarmiento-Vizcaíno, Miguel Osset, Ignacio Pérez-Victoria, Jesús Martín, Nuria de Pedro, Mercedes de la Cruz, Caridad Díaz, Francisca Vicente, Fernando Reyes, Luis A García, Gloria Blanco
The present article describes the isolation of a new natural product of the lobophorin family, designated as lobophorin K (1), from cultures of the marine actinobacteria Streptomyces sp. M-207, previously isolated from the cold-water coral Lophelia pertusa collected at 1800 m depth during an expedition to the submarine Avilés Canyon. Its structure was determined using a combination of spectroscopic techniques, mainly ESI-TOF MS and 1D and 2D NMR. This new natural product displayed cytotoxic activity against two human tumor cell lines, such as pancreatic carcinoma (MiaPaca-2) and breast adenocarcinoma (MCF-7)...
May 19, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28534619/quantitative-solid-state-nmr-study-on-ligand-surface-interaction-in-cysteine-capped-cdse-magic-sized-clusters
#16
Takuya Kurihara, Yasuto Noda, Kiyonori Takegoshi
Ligand-surface interaction of semiconductor nanoparticles (NPs) controls their optoelectronic properties, and thus examinations of the interaction are essential for the nanoelectronic applications of NPs. Herein, solid-state nuclear magnetic resonance (NMR) is performed to unravel the ligand-surface interaction in cysteine-capped CdSe magic-sized clusters. (15)N-(113)Cd through-bond J-filtered NMR directly shows the presence of the nitrogen-cadmium chemical bond for the first time and indicates that ~43% of the amines form the chemical bond...
May 23, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28534579/deprotonated-meso-hydroxyporphyrin-as-a-stable-%C3%AF-electronic-anion-the-building-unit-of-an-ion-pairing-assembly
#17
Yoshifumi Sasano, Nobuhiro Yasuda, Hiromitsu Maeda
The Ni(II) complex of 5-hydroxy-10,15,20-tris(pentafluorophenyl)-porphyrin was synthesized as the precursor of a negatively charged π-electronic system. Deprotonation, which was examined through UV/vis and (1)H NMR spectra, provided an anionic species as the building unit of an ion-pairing assembly in combination with an aliphatic cation.
May 23, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28534573/solvent-dependent-nuclearity-geometry-and-catalytic-activity-of-sphos-pd-ph-cl-2
#18
John B Brazier, Mark A Newton, Elena M Barreiro, Luis A Adrio, Leticia Naya, King Kuok Mimi Hii
The nuclearity and structures of the palladium complex [(SPhos)Pd(Ph)Cl]2 in the solid and solution states are revisited using a combination of Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, NMR spectroscopy, mass spectrometry, DFT calculations and trapping experiments. The complex was tested for its catalytic activity in the coupling reaction between chlorobenzene and n-hexylamine, where different deactivation behaviours were observed in toluene, 1,4-dioxane and DMF.
May 23, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28534571/toward-high-resolution-nmr-spectroscopy-of-microscopic-liquid-samples
#19
Mark C Butler, Hardeep S Mehta, Ying Chen, Patrick N Reardon, Ryan S Renslow, Michael Khbeis, Duane Irish, Karl T Mueller
A longstanding limitation of high-resolution NMR spectroscopy is the requirement for samples to have macroscopic dimensions. Commercial probes, for example, are designed for volumes of at least 5 μL, in spite of decades of work directed toward the goal of miniaturization. Progress in miniaturizing inductive detectors has been limited by a perceived need to meet two technical requirements: (1) minimal separation between the sample and the detector, which is essential for sensitivity, and (2) near-perfect magnetic-field homogeneity at the sample, which is typically needed for spectral resolution...
May 23, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28534444/chemical-constituents-from-the-stems-of-hydrangea-paniculata
#20
Jie Ma, Hua Sun, Chuang-Jun Li, Jing-Zhi Yang, Fang-You Chen, Dong-Ming Zhang
Further study on the constituents from the stems of Hydrangea paniculata Sieb resulted in isolation of two new compounds 1-2, including 1 monoterpenoid and 1 phenolic glycoside, along with 10 known compounds. Their structures were elucidated on the basis of spectroscopic data, including UV, IR, MS, and NMR experiments, along with chemical methods. At 10 μM, compounds 1 and 2 exhibited comparable activities with bicyclol in vitro assays for hepatoprotective activity against APAP-induced HepG2 cell damage.
June 2017: Journal of Asian Natural Products Research
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