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Dynamic nuclear polarization

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https://www.readbyqxmd.com/read/28742127/tpc1-is-an-important-zn-ii-2cys6-transcriptional-regulator-required-for-polarized-growth-and-virulence-in-the-rice-blast-fungus
#1
Rita Galhano, Adriana Illana, Lauren S Ryder, Julio Rodríguez-Romero, Marie Demuez, Muhammad Badaruddin, Ana Lilia Martinez-Rocha, Darren M Soanes, David J Studholme, Nicholas J Talbot, Ane Sesma
The establishment of polarity is a critical process in pathogenic fungi, mediating infection-related morphogenesis and host tissue invasion. Here, we report the identification of TPC1 (Transcription factor for Polarity Control 1), which regulates invasive polarized growth in the rice blast fungus Magnaporthe oryzae. TPC1 encodes a putative transcription factor of the fungal Zn(II)2Cys6 family, exclusive to filamentous fungi. Tpc1-deficient mutants show severe defects in conidiogenesis, infection-associated autophagy, glycogen and lipid metabolism, and plant tissue colonisation...
July 24, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28714674/characterization-of-chemical-exchange-using-relaxation-dispersion-of-hyperpolarized-nuclear-spins
#2
Mengxiao Liu, Yaewon Kim, Christian Hilty
Chemical exchange phenomena are ubiquitous in macromolecules, which undergo conformational change or ligand complexation. NMR relaxation dispersion (RD) spectroscopy based on a Carr-Purcell-Meiboom-Gill pulse sequence is widely applied to identify the exchange and measure the life time of intermediate states on the millisecond time scale. Advances in hyperpolarization methods improve the applicability of NMR spectroscopy when rapid acquisitions or low concentrations are required, through an increase in signal strength by several orders of magnitude...
July 17, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28712722/cell-polarity-regulates-biased-myosin-activity-and-dynamics-during-asymmetric-cell-division-via-drosophila-rho-kinase-and-protein-kinase-n
#3
Anna Tsankova, Tri Thanh Pham, David Salvador Garcia, Fabian Otte, Clemens Cabernard
Cell and tissue morphogenesis depends on the correct regulation of non-muscle Myosin II, but how this motor protein is spatiotemporally controlled is incompletely understood. Here, we show that in asymmetrically dividing Drosophila neural stem cells, cell intrinsic polarity cues provide spatial and temporal information to regulate biased Myosin activity. Using live cell imaging and a genetically encoded Myosin activity sensor, we found that Drosophila Rho kinase (Rok) enriches for activated Myosin on the neuroblast cortex prior to nuclear envelope breakdown (NEB)...
July 24, 2017: Developmental Cell
https://www.readbyqxmd.com/read/28711061/relation-between-cidnp-formed-upon-geminate-and-bulk-recombination-of-radical-pairs
#4
Denis V Sosnovsky, Olga B Morozova, Alexandra V Yurkovskaya, Konstantin L Ivanov
A theoretical approach to time-resolved Chemically Induced Dynamic Nuclear Polarization (CIDNP) is proposed, which allows one to obtain the general relation between polarization formed upon recombination of geminate spin-correlated radical pairs, the so-called G-pairs, and upon recombination of radical pairs formed by encounters of free radicals in solution, the so-called F-pairs. This relation is described by a universal parameter denoted as γ. In this work, the γ value is computed for the arbitrary spin multiplicity, singlet or triplet, of the precursor of the G-pairs as well as for arbitrary recombination rate constants of radical pairs in singlet and triplet states, kS and kT, respectively...
July 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28709996/applications-of-solid-state-nmr-to-membrane-proteins
#5
REVIEW
Vladimir Ladizhansky
Membrane proteins mediate flow of molecules, signals, and energy between cells and intracellular compartments. Understanding membrane protein function requires a detailed understanding of the structural and dynamic properties involved. Lipid bilayers provide a native-like environment for structure-function investigations of membrane proteins. In this review we give a general discourse on the recent progress in the field of solid-state NMR of membrane proteins. Solid-state NMR is a variation of NMR spectroscopy that is applicable to molecular systems with restricted mobility, such as high molecular weight proteins and protein complexes, supramolecular assemblies, or membrane proteins in a phospholipid environment...
July 11, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28708395/dynamic-nuclear-polarization-of-long-lived-nuclear-spin-states-in-methyl-groups
#6
Jean-Nicolas Dumez, Basile Vuichoud, Daniele Mammoli, Aurélien Bornet, Arthur C Pinon, Gabriele Stevanato, Benno Meier, Geoffrey Bodenhausen, Sami Jannin, Malcolm H Levitt
We have induced hyperpolarized long-lived states in compounds containing 13C-bearing methyl groups by dynamic nuclear polarization (DNP) at cryogenic temperatures, followed by dissolution with a warm solvent. The hyperpolarized methyl long-lived states give rise to enhanced antiphase 13C NMR signals in solution, which often persist for times much longer than the 13C and 1H spin-lattice relaxation times under the same conditions. The DNP-induced effects are similar to quantum-rotor-induced-polarization (QRIP), but are observed in a wider range of compounds, since they do not depend critically on the height of the rotational barrier...
July 14, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28693471/spatial-pattern-analysis-of-nuclear-migration-in-remodelled-muscles-during-drosophila-metamorphosis
#7
Kuleesha, Lin Feng, Martin Wasser
BACKGROUND: Many human muscle wasting diseases are associated with abnormal nuclear localization. During metamorphosis in Drosophila melanogaster, multi-nucleated larval dorsal abdominal muscles either undergo cell death or are remodeled to temporary adult muscles. Muscle remodeling is associated with anti-polar nuclear migration and atrophy during early pupation followed by polar migration and muscle growth during late pupation. Muscle remodeling is a useful model to study genes involved in myonuclear migration...
July 10, 2017: BMC Bioinformatics
https://www.readbyqxmd.com/read/28692804/dynamic-nuclear-polarization-efficiency-increased-by-very-fast-magic-angle-spinning
#8
Sachin R Chaudhari, Dorothea Wisser, Arthur C Pinon, Pierrick Berruyer, David Gajan, Paul Tordo, Olivier Ouari, Christian Reiter, Frank Engelke, Christophe Copéret, Moreno Lelli, Anne Lesage, Lyndon Emsley
Dynamic Nuclear Polarization has recently emerged as a tool to enhance the sensitivity of solid-state NMR experiments. However, so far high enhancements (>100) are limited to relatively low magnetic fields, and DNP at fields higher than 9.4 T significantly drops in efficiency. Here we report solid-state Overhauser effect DNP enhancements of over 100 at 18.8 T. This is achieved through the unexpected discovery that enhancements increase rapidly with increasing magic angle spinning rates. The measurements are made using 1,3-bisdiphenylene-2-phenylallyl (BDPA) dissolved in ortho-terphenyl (OTP) at 40 kHz MAS...
July 10, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28692150/acidity-strength-of-solid-catalysts-probed-by-hyperpolarized-natural-abundance-17-o-nmr-spectroscopy
#9
Frédéric Blanc
Observation of Brønsted acid sites: By enhancing the solid-state NMR signals of (17) O at natural abundance with dynamic nuclear polarization (DNP), Pruski et al. were able to measure oxygen-proton distances accurately with sub-picometer precision. The results give insight into the Brønsted acidity of a range of solid acid catalysts.
July 10, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28688430/imaging-of-rotational-wave-function-in-photodissociation-of-rovibrationally-excited-hcl-molecules
#10
K Grygoryeva, J Rakovský, O Votava, M Fárník
We demonstrate a visualization of quantum mechanical phenomena with the velocity map imaging (VMI) technique, combining vibrationally mediated photodissociation (VMP) of a simple diatomic HCl with the VMI of its H-photofragments. Free HCl molecules were excited by a pump infrared (IR) laser pulse to particular rotational J levels of the v = 2 vibrational state, and subsequently a probe ultraviolet laser photodissociated the molecule at a fixed wavelength of 243.07 nm where also the H-fragments were ionized...
July 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28685470/construction-of-0-15-tesla-overhauser-enhanced-mri
#11
Yuumi Tokunaga, Motonao Nakao, Tatsuya Naganuma, Kazuhiro Ichikawa
Overhauser enhanced MRI (OMRI) is one of the free radical imaging technologies and has been used in biomedical research such as for partial oxygen measurements in tumor, and redox status in acute oxidative diseases. The external magnetic field of OMRI is frequently in the range of 5-10 mTesla to ensure microwave penetration into small animals, and the S/N ratio is limited. In this study, a 0.15 Tesla OMRI was constructed and tested to improve the S/N ratio for a small sample, or skin measurement. Specification of the main magnet was as follows: 0...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28659585/evidence-for-rapid-oxidative-phosphorylation-and-lactate-fermentation-in-motile-human-sperm-by-hyperpolarized-13-c-magnetic-resonance-spectroscopy
#12
Steven Reynolds, Nurul Fadhlina Bt Ismail, Sarah J Calvert, Allan A Pacey, Martyn N J Paley
Poor sperm motility is a common cause of male infertility for which there are no empirical therapies. Sperm motility is powered by adenosine triphosphate but the relative importance of lactate fermentation and Oxidative Phosphorylation (OxPhos) is debated. To study the relationship between energy metabolism and sperm motility we used dissolution Dynamic Nuclear Polarization (dDNP) for the first time to show the rapid conversion of (13)C1-pyruvate to lactate and bicarbonate, indicating active glycolytic and OxPhos metabolism in sperm...
June 28, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28658577/transferred-overhauser-dnp-a-fast-efficient-approach-for-room-temperature-13-c-odnp-at-moderately-low-fields-and-natural-abundance
#13
Arnab Dey, Abhishek Banerjee, Narayanan Chandrakumar
Overhauser Dynamic Nuclear Polarization (ODNP) is investigated at a moderately low field (1.2 T) for natural abundance 13C NMR of small molecules in solution state at room temperature. It is shown that ODNP transferred from 1H to 13C by NMR coherence transfer is in general significantly more efficient than direct ODNP of 13C. Compared to direct 13C ODNP, we demonstrate over four-fold higher 13C sensitivity (signal-to-noise ratio, SNR), achieved in one-eighth of the measurement time by transferred ODNP (t-ODNP)...
June 28, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28655279/solid-state-deuterium-nmr-study-of-lk%C3%AE-14-peptide-aggregation-in-biosilica
#14
Helen E Ferreira, Gary P Drobny
In nature, organisms including diatoms, radiolaria, and marine sponges use proteins, long chain polyamines, and other organic molecules to regulate the assembly of complex silica-based structures. Here, the authors investigate structural features of small peptides, designed to mimic the silicifying activities of larger proteins found in natural systems. LKα14 (Ac-LKKLLKLLKKLLKL-C), an amphiphilic lysine/leucine repeat peptide with an α-helical secondary structure at polar/apolar interfaces, coprecipitates with silica to form nanospheres...
June 27, 2017: Biointerphases
https://www.readbyqxmd.com/read/28653507/t1-nuclear-magnetic-relaxation-dispersion-of-hyperpolarized-sodium-and-cesium-hydrogencarbonate-13-c
#15
Francisco M Martínez-Santiesteban, Thien Phuoc Dang, Heeseung Lim, Albert P Chen, Timothy J Scholl
In vivo pH mapping in tissue using hyperpolarized hydrogencarbonate-(13) C has been proposed as a method to study tumor growth and treatment and other pathological conditions related to pH changes. The finite spin-lattice relaxation times (T1 ) of hyperpolarized media are a significant limiting factor for in vivo imaging. Relaxation times can be measured at standard magnetic fields (1.5 T, 3.0 T etc.), but no such data are available at low fields, where T1 values can be significantly shorter. This information is required to determine the potential loss of polarization as the agent is dispensed and transported from the polarizer to the MRI scanner...
June 27, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28652206/membrane-solid-state-nmr-in-canada-a-historical-perspective
#16
REVIEW
Michèle Auger
This manuscript presents an overview of more than 40years of membrane solid-state nuclear magnetic resonance (NMR) research in Canada. This technique is a method of choice for the study of the structure and dynamics of lipid bilayers; bilayer interactions with a variety of molecules such as membrane peptides, membrane proteins and drugs; and to investigate membrane peptide and protein structure, dynamics, and topology. Canada has a long tradition in this field of research, starting with pioneering work on natural and model membranes in the 1970s in a context of emergence of biophysics in the country...
June 23, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28646173/transmembrane-interactions-of-full-length-mammalian-bitopic-cytochrome-p450-cytochrome-b5-complex-in-lipid-bilayers-revealed-by-sensitivity-enhanced-dynamic-nuclear-polarization-solid-state-nmr-spectroscopy
#17
Kazutoshi Yamamoto, Marc A Caporini, Sang-Choul Im, Lucy Waskell, Ayyalusamy Ramamoorthy
The dynamic protein-protein and protein-ligand interactions of integral bitopic membrane proteins with a single membrane-spanning helix play a plethora of vital roles in the cellular processes associated with human health and diseases, including signaling and enzymatic catalysis. While an increasing number of high-resolution structural studies of membrane proteins have successfully manifested an in-depth understanding of their biological functions, intact membrane-bound bitopic protein-protein complexes pose tremendous challenges for structural studies by crystallography or solution NMR spectroscopy...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28644482/one-thousand-fold-enhancement-of-high-field-liquid-nuclear-magnetic-resonance-signals-at-room-temperature
#18
Guoquan Liu, Marcel Levien, Niels Karschin, Giacomo Parigi, Claudio Luchinat, Marina Bennati
Nuclear magnetic resonance (NMR) is a fundamental spectroscopic technique for the study of biological systems and materials, molecular imaging and the analysis of small molecules. It detects interactions at very low energies and is thus non-invasive and applicable to a variety of targets, including animals and humans. However, one of its most severe limitations is its low sensitivity, which stems from the small interaction energies involved. Here, we report that dynamic nuclear polarization in liquid solution and at room temperature can enhance the NMR signal of (13)C nuclei by up to three orders of magnitude at magnetic fields of ∼3 T...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28636349/water-dynamics-from-the-surface-to-the-interior-of-a-supramolecular-nanostructure
#19
Julia H Ortony, Baofu Qiao, Christina J Newcomb, Timothy J Keller, Liam C Palmer, Elad Deiss-Yehiely, Monica Olvera de la Cruz, Songi Han, Samuel I Stupp
Water within and surrounding the structure of a biological system adopts context-specific dynamics that mediate virtually all of the events involved in the inner workings of a cell. These events range from protein folding and molecular recognition to the formation of hierarchical structures. Water dynamics are mediated by the chemistry and geometry of interfaces where water and biomolecules meet. Here we investigate experimentally and computationally the translational dynamics of vicinal water molecules within the volume of a supramolecular peptide nanofiber measuring 6...
June 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28631929/-13-c-dynamic-nuclear-polarization-using-a-trimeric-gd-3-complex-as-an-additive
#20
Peter Niedbalski, Christopher Parish, Qing Wang, Andhika Kiswandhi, Zahra Hayati, Likai Song, Lloyd Lumata
Dissolution dynamic nuclear polarization (DNP) is one of the most successful techniques that resolves the insensitivity problem in liquid-state nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) by amplifying the signal by several thousand-fold. One way to further improve the DNP signal is the inclusion of trace amounts of lanthanides in DNP samples doped with trityl OX063 free radical as the polarizing agent. In practice, stable monomeric gadolinium complexes such as Gd-DOTA or Gd-HP-DO3A are used as beneficial additives in DNP samples, further boosting the DNP-enhanced solid-state (13)C polarization by a factor of 2 or 3...
June 28, 2017: Journal of Physical Chemistry. A
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