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Perspectives for hyperpolarisation in compact NMR
Mar 22, 2017 - 3:37 PM - by nmrlearner
nmrlearner's Avatar From The DNP-NMR Blog:

Perspectives for hyperpolarisation in compact NMR

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Halse, M.E., Perspectives for hyperpolarisation in compact NMR. TrAC Trends in Analytical Chemistry, 2016. 83, Part A: p. 76-83.


http://dx.doi.org/10.1016/j.trac.2016.05.004


Nuclear magnetic resonance (NMR) is one of the most powerful analytical techniques currently available, with applications in fields ranging from synthetic chemistry to clinical diagnosis. Due to the size and cost of high-field spectrometers, NMR is generally considered to be ill-suited for industrial environments and field work. This conventional wisdom is currently being challenged through the development of NMR systems that are smaller, cheaper, more robust and portable. Despite remarkable progress in this area, potential applications are often limited by low sensitivity. Hyperpolarisation techniques have the potential to overcome this limitation and revolutionise the use of compact NMR. This review describes the state-of-the-art in NMR hyperpolarisation and presents promising examples of its application to compact NMR. Both the benefits and challenges associated with the different hyperpolarisation approaches are discussed and applications where these technologies have the potential to make a significant impact are highlighted.
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0 Replies | 3 Views
[NMR paper] Molecular study of mucin-procyanidin interaction by fluorescence quenching and Saturation Transfer Difference (STD)-NMR.
Mar 21, 2017 - 11:26 PM - by nmrlearner
nmrlearner's Avatar Molecular study of mucin-procyanidin interaction by fluorescence quenching and Saturation Transfer Difference (STD)-NMR.

Related Articles Molecular study of mucin-procyanidin interaction by fluorescence quenching and Saturation Transfer Difference (STD)-NMR.

Food Chem. 2017 Aug 01;228:427-434

Authors: Brandão E, Santos Silva M, García-Estévez I, Mateus N, de Freitas V, Soares S

Abstract
Astringency is closely related to the interaction between procyanidins and salivary proteins (SP). The aim of this work was to study the interaction between mucin, a SP responsible for saliva lubricating properties, with different procyanidins (B4 dimer, tetramer (TT) and fractions of oligomeric procyanidins), and the influence of several conditions [pH, ionic strength, procyanidins' mean degree of polymerization (mDP) and different solvents (ethanol or dimethylsulfoxide)] on this interaction by fluorescence quenching and Saturation Transfer Difference (STD)-NMR. For fractions of oligomeric procyanidins, the mucin-procyanidin interaction increased with mDP; however, for pure compounds, procyanidin TT has lower affinity than dimer B4 which could be due to a lower structural flexibility imposed by its complex structure. Furthermore, EtOH and DMSO can disrupt the main driving forces of these interactions, hydrophobic interactions and hydrogen bonds, respectively, lowering significantly the binding constants.
... [Read More]
0 Replies | 9 Views
[NMR paper] Oligomerization of the antimicrobial peptide Protegrin-5 in a membrane-mimicking environment. Structural studies by high-resolution NMR spectroscopy.
Mar 21, 2017 - 11:26 PM - by nmrlearner
nmrlearner's Avatar Oligomerization of the antimicrobial peptide Protegrin-5 in a membrane-mimicking environment. Structural studies by high-resolution NMR spectroscopy.

Related Articles Oligomerization of the antimicrobial peptide Protegrin-5 in a membrane-mimicking environment. Structural studies by high-resolution NMR spectroscopy.

Eur Biophys J. 2017 Apr;46(3):293-300

Authors: Usachev KS, Kolosova OA, Klochkova EA, Yulmetov AR, Aganov AV, Klochkov VV

Abstract
Protegrin pore formation is believed to occur in a stepwise fashion that begins with a nonspecific peptide interaction with the negatively charged bacterial cell walls via hydrophobic and positively charged amphipathic surfaces. There are five known nature protegrins (PG1-PG5), and early studies of PG-1 (PDB ID:1PG1) shown that it could form antiparallel dimer in membrane mimicking environment which could be a first step for further oligomeric membrane pore formation. Later, we solved PG-2 (PDB ID:2MUH) and PG-3 (PDB ID:2MZ6) structures in the same environment and for PG-3 observed a strong d?? NOE effects... [Read More]
0 Replies | 10 Views
DirectNMR Evidence that Transient Tautomeric andAnionic States in dG·dT Form Watson–Crick-like Base Pairs
Mar 21, 2017 - 8:29 AM - by nmrlearner
nmrlearner's Avatar DirectNMR Evidence that Transient Tautomeric andAnionic States in dG·dT Form Watson–Crick-like Base Pairs

Eric S. Szymanski, Isaac J. Kimsey and Hashim M. Al-Hashimi



Journal of the American Chemical Society
DOI: 10.1021/jacs.7b01156




Source: Journal of the American Chemical Society
0 Replies | 8 Views
Dynamic Nuclear Polarization Signal Enhancement with High-Affinity Biradical Tags #DNPNMR
Mar 20, 2017 - 5:16 PM - by nmrlearner
nmrlearner's Avatar From The DNP-NMR Blog:

Dynamic Nuclear Polarization Signal Enhancement with High-Affinity Biradical Tags #DNPNMR

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Rogawski, R., et al., Dynamic Nuclear Polarization Signal Enhancement with High-Affinity Biradical Tags. The Journal of Physical Chemistry B, 2017. 121(6): p. 1169-1175.

http://dx.doi.org/10.1021/acs.jpcb.6b09021


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 codissolved 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. With TMP-T bound to DHFR, large enhancements of the protein spectrum are observed, comparable to when TOTAPOL is codissolved with the protein. In contrast to TOTAPOL, the tight binding TMP-T can be added stoichiometrically at radical concentrations orders of magnitude lower than in previously described preparations. Benefits of the reduced radical concentration include reduced spectral bleaching, reduced chemical perturbation of the sample, and the ability to selectively enhance signals for the protein of interest.
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Probing conformational dynamics in biomolecules via chemical exchange saturation transfer: a primer
Mar 19, 2017 - 10:38 PM - by nmrlearner
nmrlearner's Avatar Probing conformational dynamics in biomolecules via chemical exchange saturation transfer: a primer

Abstract

Although Chemical Exchange Saturation Transfer (CEST) type NMR experiments have been used to study chemical exchange processes in molecules since the early 1960s, there has been renewed interest in the past several years in using this approach to study biomolecular conformational dynamics. The methodology is particularly powerful for the study of sparsely populated, transiently formed conformers that are recalcitrant to investigation using traditional biophysical tools, and it is complementary to relaxation dispersion and magnetization transfer experiments that have traditionally been used to study chemical exchange processes. Here we discuss the concepts behind the CEST experiment, focusing on practical aspects as well, we review some of the pulse sequences that have been developed to characterize protein and RNA conformational dynamics, and we discuss a number of examples where the CEST methodology has provided important insights into the role of dynamics in biomolecular function.



Source: Journal of Biomolecular NMR
0 Replies | 20 Views
[NMR paper] Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment.
Mar 19, 2017 - 10:38 PM - by nmrlearner
nmrlearner's Avatar Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment.

Related Articles Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment.

Phys Rev Lett. 2017 Mar 03;118(9):097801

Authors: Palit S, He L, Hamilton WA, Yethiraj A, Yethiraj A

Abstract
The effect of particles on the behavior of polymers in solution is important in a number of important phenomena such as the effect of "crowding" proteins in cells, colloid-polymer mixtures, and nanoparticle "fillers" in polymer solutions and melts. In this Letter, we study the effect of spherical inert nanoparticles (which we refer to as "crowders") on the diffusion coefficient and radius of gyration of polymers in solution using pulsed-field-gradient NMR and small-angle neutron scattering (SANS), respectively. The diffusion coefficients exhibit a plateau below a characteristic polymer concentration, which we identify as the overlap threshold concentration c^{?}. Above c^{?}, in a crossover region between the dilute and semidilute regimes, the (long-time) self-diffusion coefficients are found, universally, to decrease exponentially with polymer concentration at all crowder packing fractions, consistent with a structural basis for the long-time dynamics. The radius of gyration obtained... [Read More]
0 Replies | 14 Views
[NMR paper] Structural Analysis of Human Cofilin 2/Filamentous Actin Assemblies: Atomic-Resolution Insights from Magic Angle Spinning NMR Spectroscopy.
Mar 19, 2017 - 10:38 PM - by nmrlearner
nmrlearner's Avatar Structural Analysis of Human Cofilin 2/Filamentous Actin Assemblies: Atomic-Resolution Insights from Magic Angle Spinning NMR Spectroscopy.

Related Articles Structural Analysis of Human Cofilin 2/Filamentous Actin Assemblies: Atomic-Resolution Insights from Magic Angle Spinning NMR Spectroscopy.

Sci Rep. 2017 Mar 17;7:44506

Authors: Yehl J, Kudryashova E, Reisler E, Kudryashov D, Polenova T

Abstract
Cellular actin dynamics is an essential element of numerous cellular processes, such as cell motility, cell division and endocytosis. Actin's involvement in these processes is mediated by many actin-binding proteins, among which the cofilin family plays unique and essential role in accelerating actin treadmilling in filamentous actin (F-actin) in a nucleotide-state dependent manner. Cofilin preferentially interacts with older filaments by recognizing time-dependent changes in F-actin structure associated with the hydrolysis of ATP and release of inorganic phosphate (Pi) from the nucleotide cleft of actin. The structure of cofilin on F-actin and the details of the intermolecular interface remain poorly understood at atomic resolution. Here we report atomic-level characterization by magic angle spinning (MAS) NMR of the muscle isoform of human cofilin 2 (CFL2) bound to F-actin. We demonstrate that resonance assignments for the majority of atoms are readily accomplished and we derive the... [Read More]
0 Replies | 13 Views
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