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Surface-selective direct 17O DNP NMR of CeO2 nanoparticles #DNPNMR
Jun 05, 2017 - 3:59 PM - by nmrlearner
nmrlearner's Avatar From The DNP-NMR Blog:

Surface-selective direct 17O DNP NMR of CeO2 nanoparticles #DNPNMR

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Hope, M.A., et al., Surface-selective direct 17O DNP NMR of CeO2 nanoparticles. Chem Commun (Camb), 2017. 53(13): p. 2142-2145.


https://www.ncbi.nlm.nih.gov/pubmed/28134945


Surface-selective direct 17O DNP has been demonstrated for the first time on CeO2 nanoparticles, for which the first three layers can be distinguished with high selectivity. Polarisation build-up curves show that the polarisation of the (sub-)surface sites builds up faster than the bulk, accounting for the remarkable surface selectivity.
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Biomolecular MRI Reporters: evolution of new mechanisms
Jun 05, 2017 - 3:02 AM - by nmrlearner
nmrlearner's Avatar Biomolecular MRI Reporters: evolution of new mechanisms


Publication date: Available online 3 June 2017
Source:Progress in Nuclear Magnetic Resonance Spectroscopy

Author(s): Arnab Mukherjee, Hunter C. Davis, Pradeep Ramesh, George J. Lu, Mikhail G. Shapiro

Magnetic resonance imaging (MRI) is a powerful technique for observing the function of specific cells and molecules inside living organisms. However, compared to optical microscopy, in which fluorescent protein reporters are available to visualize hundreds of cellular functions ranging from gene expression and chemical signaling to biomechanics, to date relatively few such reporters are available for MRI. Efforts to develop MRI-detectable biomolecules have mainly focused on proteins containing or transporting paramagnetic metals for T1 and T2 relaxation enhancement or large numbers of exchangeable protons for chemical exchange saturation transfer. While these pioneering developments established several key uses of biomolecular MRI, such as imaging of gene expression and functional biosensing, they also revealed that low molecular sensitivity poses a major challenge for broader adoption in biology and medicine. Recently, new classes of biomolecular reporters have been developed based on alternative contrast mechanisms, including enhancement of spin diffusivity, interactions with hyperpolarized nuclei, and modulation of blood flow. These novel... [Read More]
0 Replies | 47 Views
[NMR paper] Recent advances in measuring the kinetics of biomolecules by NMR relaxation dispersion spectroscopy.
Jun 05, 2017 - 3:02 AM - by nmrlearner
nmrlearner's Avatar Recent advances in measuring the kinetics of biomolecules by NMR relaxation dispersion spectroscopy.

Related Articles Recent advances in measuring the kinetics of biomolecules by NMR relaxation dispersion spectroscopy.

Arch Biochem Biophys. 2017 May 30;:

Authors: Ban D, Smith CA, de Groot BL, Griesinger C, Lee D

Abstract
Protein function can be modulated or dictated by the amplitude and timescale of biomolecular motion, therefore it is imperative to study protein dynamics. Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful technique capable of studying timescales of motion that range from those faster than molecular reorientation on the picosecond timescale to those that occur in real-time. Across this entire regime, NMR observables can report on the amplitude of atomic motion, and the kinetics of atomic motion can be ascertained with a wide variety of experimental techniques from real-time to milliseconds and several nanoseconds to picoseconds. Still a four orders of magnitude window between several nanoseconds and tens of microseconds has remained elusive. Here, we highlight new relaxation dispersion NMR techniques that serve to cover this "hidden-time" window up to hundreds of nanoseconds that achieve atomic resolution while studying the molecule under physiological conditions.


PMID: 28576576 [PubMed - as supplied by publisher]


... [Read More]
0 Replies | 162 Views
Visualizing RNA-protein Interactions in Live Human Cells - Bioscience Technology
Jun 03, 2017 - 11:49 AM - by nmrlearner
nmrlearner's Avatar Visualizing RNA-protein Interactions in Live Human Cells - Bioscience Technology


Bioscience Technology


Visualizing RNA-protein Interactions in Live Human Cells
Bioscience Technology
UAlbany chemists Alan Chen Ph.D, Maksim Royzen Ph.D, and Alex Shekhtman Ph.D have combined their labs on a collaborative project aimed at visualizing RNA-protein interactions inside live human cells by using multi-dimensional NMR (nuclear ...


... [Read More]
0 Replies | 117 Views
[NMR paper] Dynamic nuclear polarization / solid-state NMR of membrane polypeptides. Free radical optimization for matrix-free lipid bilayer samples.
Jun 03, 2017 - 11:49 AM - by nmrlearner
nmrlearner's Avatar Dynamic nuclear polarization / solid-state NMR of membrane polypeptides. Free radical optimization for matrix-free lipid bilayer samples.

Related Articles Dynamic nuclear polarization / solid-state NMR of membrane polypeptides. Free radical optimization for matrix-free lipid bilayer samples.

Chemphyschem. 2017 Jun 02;:

Authors: Ouari O, Salnikov ES, Abel S, Karthikeyan G, Karoui H, Aussenac F, Tordo P, Bechinger B

Abstract
Dynamic Nuclear Polarization boosts the sensitivity of NMR spectroscopy by orders of magnitude making possible investigations previously out of scope. For MAS solid-state NMR studies the samples are typically mixed with biradicals dissolved in glass forming solvent and investigated at 100K. Here we present new biradical polarizing agents developed for matrix-free samples such as supported lipid bilayers, which are systems widely used for the investigation of membrane proteins of high biomedical importance. A series of 11 biradicals with different structure, geometry and physico-chemical properties was comprehensively tested for DNP performance in lipid bilayers, some of them developed specifically for membranes investigations. The membrane-anchored biradicals PyPol-C16, AMUPOL-cholesterol and bTurea-C16 exhibit improved g-tensor alignment, inter-radical distance and dispersion, and the highest signal enhancement factors so far obtained for matrix-free membranes or other... [Read More]
0 Replies | 73 Views
[NMR paper] Backbone NMR assignments of tryparedoxin, the central protein in the hydroperoxide detoxification cascade of African trypanosomes, in the oxidized and reduced form.
Jun 03, 2017 - 11:49 AM - by nmrlearner
nmrlearner's Avatar Backbone NMR assignments of tryparedoxin, the central protein in the hydroperoxide detoxification cascade of African trypanosomes, in the oxidized and reduced form.

Related Articles Backbone NMR assignments of tryparedoxin, the central protein in the hydroperoxide detoxification cascade of African trypanosomes, in the oxidized and reduced form.

Biomol NMR Assign. 2017 Jun 01;:

Authors: Wagner A, Diehl E, Krauth-Siegel RL, Hellmich UA

Abstract
Tryparedoxin (Tpx) is a pivotal protein in the redox-metabolism of trypanosomatid parasites. Tpx has previously been identified as a potential target for drug development in the fight against human African sleeping sickness caused by Trypanosoma brucei. Tpx belongs to the thioredoxin superfamily and acts as an oxidoreductase in the parasite's cytoplasm. It contains a WCPPC active site motif, which enables the protein to undergo thiol-disulfide exchange. To promote future protein-drug interaction analyses, we report the (1)H, (13)C and (15)N backbone chemical shift assignments for both the oxidized and reduced states of Tpx. The redox state of the protein has a significant impact on the chemical shifts of the residues at the active site of the protein, especially on the two redox active site cysteines. The NMR assignments presented here will be a prerequisite for investigating drug binding to Tpx in molecular detail and to drive further drug... [Read More]
0 Replies | 78 Views
[NMR paper] A general mechanism of photoconversion of green-to-red fluorescent proteins based on blue and infrared light reduces phototoxicity in live-cell single-molecule imaging
Jun 02, 2017 - 8:33 PM - by nmrlearner
nmrlearner's Avatar A general mechanism of photoconversion of green-to-red fluorescent proteins based on blue and infrared light reduces phototoxicity in live-cell single-molecule imaging


Photoconversion of fluorescent proteins by blue and complementary near-infrared light, termed primed conversion (PC), is a mechanism recently discovered for Dendra2. We demonstrate that controlling the conformation of arginine at residue 66 by threonine at residue 69 of fluorescent proteins from Anthozoan families (Dendra2, mMaple, Eos, mKikGR, pcDronpa protein families) represents a general route to facilitate PC. Mutations of alanine 159 or serine 173, which are known to influence chromophore flexibility and allow for reversible photoswitching, prevent PC. In addition, we report enhanced photoconversion for pcDronpa variants with asparagine 116. We demonstrate live-cell single-molecule imaging with reduced phototoxicity using PC and record trajectories of RNA polymerase in Escherichia coli cells.

More...
0 Replies | 134 Views
Effect of electron spectral diffusion on static dynamic nuclear polarization at 7 Tesla #DNPNMR
Jun 02, 2017 - 8:33 PM - by nmrlearner
nmrlearner's Avatar From The DNP-NMR Blog:

Effect of electron spectral diffusion on static dynamic nuclear polarization at 7 Tesla #DNPNMR

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Leavesley, A., et al., Effect of electron spectral diffusion on static dynamic nuclear polarization at 7 Tesla. Phys. Chem. Chem. Phys., 2017. 19(5): p. 3596-3605.


https://www.ncbi.nlm.nih.gov/pubmed/28094364


Here, we present an integrated experimental and theoretical study of 1H 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. In our systematic experimental study, the DNP enhanced 1H signals are monitored as a function of microwave frequency, microwave power, radical concentration, and temperature, and are interpreted with the help of electron spin-lattice relaxation times, experimental MW irradiation parameters, and the electron spectral diffusion (eSD) model introduced previously. This comprehensive experimental DNP study with mono-nitroxide radical spin probes was accompanied with theoretical calculations. Our results consistently... [Read More]
0 Replies | 70 Views
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