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Dynamic nuclear polarization

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https://www.readbyqxmd.com/read/28099013/dynamic-nuclear-polarization-signal-enhancement-with-high-affinity-biradical-tags
#1
Rivkah Tamar Rogawski, Ivan V Sergeyev, Yongjun Li, Maria Francesca Ottaviani, Virginia W Cornish, Ann E McDermott
Dynamic nuclear polarization is an emerging technique for sensitizing solid state NMR experiments by transferring polarization from electrons to nuclei. Stable biradicals, the polarization source for the cross effect mechanism, are typically co-dissolved at millimolar concentrations with proteins of interest. Here we describe the high-affinity biradical tag TMP-T, created by covalently linking trimethoprim, a nanomolar affinity ligand of dihydrofolate reductase (DHFR), to the biradical polarizing agent TOTAPOL...
January 18, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28098267/a-tailored-multi-frequency-epr-approach-to-accurately-determine-the-magnetic-resonance-parameters-of-dynamic-nuclear-polarization-agents-application-to-amupol
#2
P Gast, D Mance, E Zurlo, K L Ivanov, M Baldus, M Huber
To understand the dynamic nuclear polarization (DNP) enhancements of biradical polarizing agents, the magnetic resonance parameters need to be known. We describe a tailored EPR approach to accurately determine electron spin-spin coupling parameters using a combination of standard (9 GHz), high (95 GHz) and ultra-high (275 GHz) frequency EPR. Comparing liquid- and frozen-solution continuous-wave EPR spectra provides accurate anisotropic dipolar interaction D and isotropic exchange interaction J parameters of the DNP biradical AMUPol...
January 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28094364/effect-of-electron-spectral-diffusion-on-static-dynamic-nuclear-polarization-at-7-tesla
#3
Alisa Leavesley, Daphna Shimon, Ting Ann Siaw, Akiva Feintuch, Daniella Goldfarb, Shimon Vega, Ilia Kaminker, Songi Han
Here, we present an integrated experimental and theoretical study of (1)H dynamic nuclear polarization (DNP) of a frozen aqueous glass containing free radicals at 7 T, under static conditions and at temperatures ranging between 4 and 20 K. The DNP studies were performed with a home-built 200 GHz quasi-optics microwave bridge, powered by a tunable solid-state diode source. DNP using monochromatic and continuous wave (cw) irradiation applied to the electron paramagnetic resonance (EPR) spectrum of the radicals induces the transfer of polarization from the electron spins to the surrounding nuclei of the solvent and solutes in the frozen aqueous glass...
January 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28093594/fast-and-accurate-mas-dnp-simulations-of-large-spin-ensembles
#4
Frédéric Mentink-Vigier, Shimon Vega, Gaël De Paëpe
A deeper understanding of parameters affecting Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP), an emerging nuclear magnetic resonance hyperpolarization method, is crucial for the development of new polarizing agents and the successful implementation of the technique at higher magnetic fields (>10 T). Such progress is currently impeded by computational limitation which prevents the simulation of large spin ensembles (electron as well as nuclear spins) and to accurately describe the interplay between all the multiple key parameters at play...
January 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28078411/in-vitro-and-in-silico-assessment-of-the-structure-dependent-binding-of-bisphenol-analogues-to-glucocorticoid-receptor
#5
Jie Zhang, Tiehua Zhang, Tianzhu Guan, Hansong Yu, Tiezhu Li
Widespread use of bisphenol A (BPA) and other bisphenol analogues has attracted increasing attention for their potential adverse effects. As environmental endocrine-disrupting compounds (EDCs), bisphenols (BPs) may activate a variety of nuclear receptors, including glucocorticoid receptor (GR). In this work, the binding of 11 BPs to GR was investigated by fluorescence polarization (FP) assay in combination with molecular dynamics simulations. The human glucocorticoid receptor was prepared as a soluble recombinant protein...
January 11, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28072398/transportable-hyperpolarized-metabolites
#6
Xiao Ji, Aurélien Bornet, Basile Vuichoud, Jonas Milani, David Gajan, Aaron J Rossini, Lyndon Emsley, Geoffrey Bodenhausen, Sami Jannin
Nuclear spin hyperpolarization of (13)C-labelled metabolites by dissolution dynamic nuclear polarization can enhance the NMR signals of metabolites by several orders of magnitude, which has enabled in vivo metabolic imaging by MRI. However, because of the short lifetime of the hyperpolarized magnetization (typically <1 min), the polarization process must be carried out close to the point of use. Here we introduce a concept that markedly extends hyperpolarization lifetimes and enables the transportation of hyperpolarized metabolites...
January 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/28063445/influence-of-dy-3-and-tb-3-doping-on-13-c-dynamic-nuclear-polarization
#7
Peter Niedbalski, Christopher Parish, Andhika Kiswandhi, Leila Fidelino, Chalermchai Khemtong, Zahra Hayati, Likai Song, André Martins, A Dean Sherry, Lloyd Lumata
Dynamic nuclear polarization (DNP) is a technique that uses a microwave-driven transfer of high spin alignment from electrons to nuclear spins. This is most effective at low temperature and high magnetic field, and with the invention of the dissolution method, the amplified nuclear magnetic resonance (NMR) signals in the frozen state in DNP can be harnessed in the liquid-state at physiologically acceptable temperature for in vitro and in vivo metabolic studies. A current optimization practice in dissolution DNP is to dope the sample with trace amounts of lanthanides such as Gd(3+) or Ho(3+), which further improves the polarization...
January 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28060330/hyperpolarized-13c-metabolic-magnetic-resonance-spectroscopy-and-imaging
#8
Eugen Kubala, Kim A Muñoz-Álvarez, Geoffrey Topping, Christian Hundshammer, Benedikt Feuerecker, Pedro A Gómez, Giorgio Pariani, Franz Schilling, Steffen J Glaser, Rolf F Schulte, Marion I Menzel, Markus Schwaiger
In the past decades, new methods for tumor staging, restaging, treatment response monitoring, and recurrence detection of a variety of cancers have emerged in conjunction with the state-of-the-art positron emission tomography with (18)F-fluorodeoxyglucose ([(18)F]-FDG PET). (13)C magnetic resonance spectroscopic imaging ((13)CMRSI) is a minimally invasive imaging method that enables the monitoring of metabolism in vivo and in real time. As with any other method based on (13)C nuclear magnetic resonance (NMR), it faces the challenge of low thermal polarization and a subsequent low signal-to-noise ratio due to the relatively low gyromagnetic ratio of (13)C and its low natural abundance in biological samples...
December 30, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28058422/spatial-distribution-of-organic-functional-groups-supported-on-mesoporous-silica-nanoparticles-a-study-by-conventional-and-dnp-enhanced-29-si-solid-state-nmr
#9
Takeshi Kobayashi, Dilini Singappuli-Arachchige, Zhuoran Wang, Igor I Slowing, Marek Pruski
Solid-state NMR spectroscopy, both conventional and dynamic nuclear polarization (DNP)-enhanced, was employed to study the spatial distribution of organic functional groups attached to the surface of mesoporous silica nanoparticles via co-condensation and grafting. The most revealing information was provided by DNP-enhanced two-dimensional (29)Si-(29)Si correlation measurements, which unambiguously showed that post-synthesis grafting leads to a more homogeneous dispersion of propyl and mercaptopropyl functionalities than co-condensation...
January 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28052402/electron-spin-resonance-studies-on-deuterated-nitroxyl-spin-probes-used-in-overhauser-enhanced-magnetic-resonance-imaging
#10
D David Jebaraj, Hideo Utsumi, A Milton Franklin Benial
The Electron Spin Resonance studies were carried out for 2 mM concentration of (14) N and (15) N -labeled 3-carbamoyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-carboxy-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and their deuterated nitroxyl radicals using X-band Electron Spin Resonance spectrometer. The ESR Line shape analysis was carried out. The Electron Spin Resonance parameters such as, linewidth, Lorentzian component, signal intensity ratio, rotational correlation time, hyperfine coupling constant and g-factor were estimated...
January 4, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28041828/non-invasive-evaluation-of-atopic-dermatitis-based-on-redox-status-using-in-vivo-dynamic-nuclear-polarization-magnetic-resonance-imaging
#11
Hinako Eto, Gaku Tsuji, Takahito Chiba, Masutaka Furue, Fuminori Hyodo
Atopic dermatitis (AD) is a chronic inflammatory condition with complex etiology, including genetic, environmental and immunologic factors. Redox imbalance caused by excessive oxidative stress has been shown to mediate disease activity of AD. Currently, an imaging technique that can monitor the redox status of the skin in vivo has not yet been developed. Consequently, we have established such a technique that can detect and visualize the redox status of the skin using in vivo dynamic nuclear polarization magnetic resonance imaging (DNP-MRI)...
December 29, 2016: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28031257/sexual-pheromone-modulates-the-frequency-of-cytosolic-ca2-bursts-in-saccharomyces-cerevisiae
#12
Natalia Carbó, Nahuel Tarkowski, Emiliano Perez Ipiña, Silvina Ponce Dawson, Pablo S Aguilar
Transient and highly regulated elevations of cytosolic Ca(2+) control a variety of cellular processes. Bulk measurements using radioactive Ca(2+) and the luminescent sensor aequorin have shown that in response to pheromone, budding yeast cells experience a rise of cytosolic Ca(2+) that is mediated by two import systems composed by the Mid1-Cch1-Ecm7 protein complex, and the Fig 1 protein. Although this response has been largely studied, there is no report on Ca(2+) dynamics at the single cell level. Here, using protein calcium indicators we show that both vegetative and pheromone-treated yeast cells exhibit discrete and asynchronous Ca(2+) bursts...
December 28, 2016: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28026949/atomic-level-structure-characterization-of-biomass-pre-and-post-lignin-treatment-by-dynamic-nuclear-polarization-enhanced-solid-state-nmr
#13
Frédéric A Perras, Hao Luo, Ximing Zhang, Nathan S Mosier, Marek Pruski, Mahdi M Abu-Omar
Lignocellulosic biomass is a promising sustainable feedstock for the production of biofuels, biomaterials, and bio-specialty chemicals. However, efficient utilization of biomass has been limited by our poor understanding of its molecular structure. Here, we report a dynamic nuclear polarization (DNP)-enhanced solid-state (SS)NMR study of the molecular structure of biomass, both pre- and post-catalytic treatment. This technique enables the measurement of 2D homonuclear (13)C-(13)C correlation SSNMR spectra under natural abundance, yielding, for the first time, an atomic-level picture of the structure of raw and catalytically treated biomass samples...
December 27, 2016: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/27997167/three-dimensional-structure-determination-of-surface-sites
#14
Pierrick Berruyer, Moreno Lelli, Matthew P Conley, Daniel L Silverio, Cory M Widdifield, Georges Siddiqi, David Gajan, Anne Lesage, Christophe Copéret, Lyndon Emsley
The spatial arrangement of atoms is directly linked to chemical function. A fundamental challenge in surface chemistry and catalysis relates to the determination of three-dimensional structures with atomic-level precision. Here we determine the three-dimensional structure of an organometallic complex on an amorphous silica surface using solid-state NMR measurements, enabled through a dynamic nuclear polarization surface enhanced NMR spectroscopy approach that induces a 200-fold increase in the NMR sensitivity for the surface species...
January 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27980510/contrast-variation-by-dynamic-nuclear-polarization-and-time-of-flight-small-angle-neutron-scattering-i-application-to-industrial-multi-component-nanocomposites
#15
Yohei Noda, Satoshi Koizumi, Tomomi Masui, Ryo Mashita, Hiroyuki Kishimoto, Daisuke Yamaguchi, Takayuki Kumada, Shin-Ichi Takata, Kazuki Ohishi, Jun-Ichi Suzuki
Dynamic nuclear polarization (DNP) at low temperature (1.2 K) and high magnetic field (3.3 T) was applied to a contrast variation study in small-angle neutron scattering (SANS) focusing on industrial rubber materials. By varying the scattering contrast by DNP, time-of-flight SANS profiles were obtained at the pulsed neutron source of the Japan Proton Accelerator Research Complex (J-PARC). The concentration of a small organic molecule, (2,2,6,6-tetramethylpiperidine-1-yl)oxy (TEMPO), was carefully controlled by a doping method using vapour sorption into the rubber specimens...
December 1, 2016: Journal of Applied Crystallography
https://www.readbyqxmd.com/read/27934234/heteronuclear-cross-relaxation-under-solid-state-dynamic-nuclear-polarization
#16
Diane Daube, Victoria Aladin, Jörg Heiliger, Johannes J Wittmann, Dominic Barthelmes, Christian Bengs, Harald Schwalbe, Björn Corzilius
We report on the spontaneous polarization transfer from dynamically hyperpolarized (1)H to (13)C during magic-angle spinning dynamic nuclear polarization (DNP) at temperatures around 100 K. The transfer is mediated by (1)H-(13)C cross-relaxation within methyl groups due to reorientation dynamics, and results in an inverted (13)C NMR signal of enhanced amplitude. Further spreading of transferred polarization can then occur via (13)C-(13)C spin-diffusion. The resulting process is equal to the nuclear Overhauser effect (NOE) where typically continuous saturation of (1)H by radio frequency irradiation is employed...
December 28, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27925750/high-fidelity-bidirectional-nuclear-qubit-initialization-in-sic
#17
Viktor Ivády, Paul V Klimov, Kevin C Miao, Abram L Falk, David J Christle, Krisztián Szász, Igor A Abrikosov, David D Awschalom, Adam Gali
Dynamic nuclear polarization (DNP) is an attractive method for initializing nuclear spins that are strongly coupled to optically active electron spins because it functions at room temperature and does not require strong magnetic fields. In this Letter, we theoretically demonstrate that DNP, with near-unity polarization efficiency, can be generally realized in weakly coupled electron spin-nuclear spin systems. Furthermore, we theoretically and experimentally show that the nuclear spin polarization can be reversed by magnetic field variations as small as 0...
November 25, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27911812/cytoskeleton-dynamics-control-the-first-asymmetric-cell-division-in-arabidopsis-zygote
#18
Yusuke Kimata, Takumi Higaki, Tomokazu Kawashima, Daisuke Kurihara, Yoshikatsu Sato, Tomomi Yamada, Seiichiro Hasezawa, Frederic Berger, Tetsuya Higashiyama, Minako Ueda
The asymmetric cell division of the zygote is the initial and crucial developmental step in most multicellular organisms. In flowering plants, whether zygote polarity is inherited from the preexisting organization in the egg cell or reestablished after fertilization has remained elusive. How dynamically the intracellular organization is generated during zygote polarization is also unknown. Here, we used a live-cell imaging system with Arabidopsis zygotes to visualize the dynamics of the major elements of the cytoskeleton, microtubules (MTs), and actin filaments (F-actins), during the entire process of zygote polarization...
December 6, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27910860/dynamic-nuclear-magnetic-resonance-field-sensing-with-part-per-trillion-resolution
#19
Simon Gross, Christoph Barmet, Benjamin E Dietrich, David O Brunner, Thomas Schmid, Klaas P Pruessmann
High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude...
December 2, 2016: Nature Communications
https://www.readbyqxmd.com/read/27892752/concentration-dependence-of-nitroxyl-spin-probes-in-liposomal-solution-electron-spin-resonance-and-overhauser-enhanced-magnetic-resonance-studies
#20
V Meenakumari, Hideo Utsumi, A Jawahar, A Milton Franklin Benial
In this work, the detailed studies of electron spin resonance (ESR) and overhauser-enhanced magnetic resonance imaging (OMRI) were carried out for permeable nitroxyl spin probe, MC-PROXYL as a function of agent concentration in liposomal solution. In order to compare the impermeable nature of nitroxyl radical, the study was also carried out only at 2 mM concentration of carboxy-PROXYL. The ESR parameters were estimated using L-band and 300 MHz ESR spectrometers. The line width broadening was measured as a function of agent concentration in liposomal solution...
December 21, 2016: Journal of Liposome Research
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