Read by QxMD icon Read

Solid State Nuclear Magnetic Resonance

Clare P Grey, Tatyana Polenova, Shimon Vega
No abstract text is available yet for this article.
April 1, 2018: Solid State Nuclear Magnetic Resonance
Sivakumar Paramasivam, Angela M Gronenborn, Tatyana Polenova
Chemical shift tensors (CSTs) are an exquisite probe of local geometric and electronic structure.15 N CST are very sensitive to hydrogen bonding, yet they have been reported for very few proteins to date. Here we present experimental results and statistical analysis of backbone amide15 N CSTs for 100 residues of four proteins, two E. coli thioredoxin reassemblies (1-73-(U-13 C,15 N)/74-108-(U-15 N) and 1-73-(U-15 N)/74-108-(U-13 C,15 N)), dynein light chain 8 LC8, and CAP-Gly domain of the mammalian dynactin...
March 15, 2018: Solid State Nuclear Magnetic Resonance
Sabu Varghese, Peter J Halling, Daniel Häussinger, Stephen Wimperis
Nuclear magnetic resonance (NMR) is a powerful tool for investigating atomic-scale structure in heterogeneous or composite materials where long-range order is absent. In this work solid-state1 H and1 H-detected NMR experiments were performed with fast magic angle spinning (νR  = 75 kHz) and at high magnetic fields (B0  = 20 T) and used to gain structural insight into a heterogeneous biocatalyst consisting of an enzyme, human carbonic anhydrase II (hCA II), covalently immobilized on epoxy-functionalized silica...
March 14, 2018: Solid State Nuclear Magnetic Resonance
Takahiro Iijima, Tadashi Shimizu
The relaxation-assisted separation method was applied to overlapping2 H nuclear magnetic resonance (NMR) spectra of diamagnetic and paramagnetic solids to separate them based on the different relaxation behaviors caused by molecular motion. Carr-Purcell-Meiboom-Gill sequences for2 H NMR were adopted to build two-dimensional data sets from one-dimensional NMR experiments. For diamagnetic α-glycine, the2 H NMR spectrum collected at 198 K was separated into two components from static -CD2 - and dynamic -ND3 ...
March 8, 2018: Solid State Nuclear Magnetic Resonance
Rupal Gupta, John Stringer, Jochem Struppe, Dieter Rehder, Tatyana Polenova
Electronic and structural properties of short-lived metal-peroxido complexes, which are key intermediates in many enzymatic reactions, are not fully understood. While detected in various enzymes, their catalytic properties remain elusive because of their transient nature, making them difficult to study spectroscopically. We integrated17 O solid-state NMR and density functional theory (DFT) to directly detect and characterize the peroxido ligand in a bioinorganic V(V) complex mimicking intermediates non-heme vanadium haloperoxidases...
February 19, 2018: Solid State Nuclear Magnetic Resonance
Gregory Lusk, Terry Gullion
Some MAS NMR experiments are sensitive to fluctuations or drifts in rf field strengths. We examine the simple 1H-13C CPMAS experiment and show that the 13C signal intensities vary over time due to drifts in rf field strengths. The causes of the drifts in rf field strengths are studied. Stabilization of the rf field strengths are obtained by using an rf field-strength controller. The controller is a stand-alone unit, which can be easily incorporated in any spectrometer system. Details of the controller, including circuit design, are provided...
February 3, 2018: Solid State Nuclear Magnetic Resonance
Kaustubh R Mote, Perunthiruthy K Madhu
We show here an effective way of implementing simultaneously homonuclear and heteronuclear dipolar decoupling in magic-angle spinning (MAS) solid-state NMR. Whilst the homonuclear spin decoupling is applied on the 1 H channel, heteronuclear spin decoupling is applied on the 13 C channel. The 1 H spins are observed in a windowed fashion in this case. The resultant 1 H spectrum has higher resolution due to the attenuation of broadening arising from both homonuclear 1 H-1 H and heteronuclear 1 H-13 C interactions, with the latter normally leading to additional line broadening in 13 C labelled samples...
April 2018: Solid State Nuclear Magnetic Resonance
A M Panich, N A Sergeev, M Paczwa, M Olszewski
No abstract text is available yet for this article.
April 2018: Solid State Nuclear Magnetic Resonance
Shenhui Li, Jing Li, Jing Tang, Feng Deng
Solid-state NMR was utilized to explore the host-guest interaction between adsorbate and adsorbent at atomic level to understand the separation mechanism of styrene (St) and ethylbenzene (EB) in MIL-53(Al). 13 C-27 Al double-resonance NMR experiments revealed that the host-guest interaction between St and MIL-53 was much stronger than that of EB adsorption. In addition, 13 C DIPSHIFT experiments suggested that the adsorbed St was less mobile than EB confined inside the MIL-53 pore. Furthermore, the host-guest interaction model between St, EB and MIL-53 was established on the basis of the spatial proximities information extracted from 2D 1 H-1 H homo-nuclear correlation NMR experiments...
April 2018: Solid State Nuclear Magnetic Resonance
Jaclyn Catalano, Anna Murphy, Yao Yao, Nicholas Zumbulyadis, Silvia A Centeno, Cecil Dybowski
Many oil paintings, dating from the 15th century to the present, are affected by the formation of heavy-metal carboxylates (soaps) that alter the structural integrity and appearance of the works. Through transport phenomena not yet understood, free fatty acids formed from oils used as binders migrate through the paint film and react with heavy-metal ions that are constituents of pigments and/or driers, forming metal carboxylates. The local molecular dynamics of fatty acids and metal carboxylates are factors influencing material transport in these systems...
February 2018: Solid State Nuclear Magnetic Resonance
Otto E O Zeman, Constantin Hoch, Rupert Hochleitner, Thomas Bräuniger
Orientation-dependent NMR spectra of a single crystal of the mineral vanadinite, Pb5 (VO4 )3 Cl, were acquired using only one rotation axis with a general orientation in the hexagonal crystal lattice (space group P63 /m). The chemical shift (CS) tensors for the207 Pb on Wyckoff positions 6h and 4f, and both CS and quadrupole coupling tensor Q for51 V at the positions 6h were determined by including the NMR response of symmetry-related atoms in the unit cell (and in case of207 Pb at 4f, also the isotropic shift from MAS NMR spectra)...
February 2018: Solid State Nuclear Magnetic Resonance
Kong Ooi Tan, Vipin Agarwal, Nils-Alexander Lakomek, Susanne Penzel, Beat H Meier, Matthias Ernst
Through-bond J-coupling based experiments in solid-state NMR spectroscopy are challenging because the J couplings are typically much smaller than the dipolar couplings. This often leads to a lower transfer efficiency compared to dipolar-coupling based sequences. One of the reasons for the low transfer efficiency are the second-order cross terms involving the strong heteronuclear dipolar couplings leading to fast magnetization decay. Here, we show that by employing a symmetry-based C9 sequence, which was carefully selected to suppress second-order terms, efficient polarization transfers of up to 80% can be achieved without decoupling on fully protonated two-spin model systems at a MAS frequency of 55...
February 2018: Solid State Nuclear Magnetic Resonance
Eva Meirovitch, Zhichun Liang, Jack H Freed
We report on a new approach to the analysis of dynamic NMR lineshapes from polycrystalline (i.e., macroscopically disordered) samples in the presence of Magic Angle Spinning (MAS). This is an application of the Stochastic Liouville Equation developed by Freed and co-workers for treating restricted (i.e., microscopically ordered) motions. The2 H nucleus in an internally-mobile C-CD3 moiety serves as a prototype probe. The acronym is2 H/MOMD/MAS, where MOMD stands for "microscopic-order-macroscopic-disorder...
February 2018: Solid State Nuclear Magnetic Resonance
Abil E Aliev, Albert P Bartók, Jonathan R Yates
Two different axial symmetries of the119 Sn chemical shift anisotropy (CSA) in tin dioxide with the asymmetry parameter (η) of 0 and 0.27 were reported previously based on the analysis of MAS NMR spectra. By analyzing the static powder pattern, we show that the119 Sn CSA is axially symmetric. A nearly axial symmetry and the principal axis system of the119 Sn chemical shift tensor in SnO2 were deduced from periodic scalar-relativistic density functional theory (DFT) calculations of NMR parameters. The implications of fast small-angle motions on CSA parameters were also considered, which could potentially lead to a CSA symmetry in disagreement with a crystal symmetry...
February 2018: Solid State Nuclear Magnetic Resonance
Alexander C Forse, John M Griffin, Clare P Grey
Nuclear magnetic resonance (NMR) spectroscopy has emerged as a useful technique for probing the structure and dynamics of the electrode-electrolyte interface in supercapacitors, as ions inside the pores of the carbon electrodes can be studied separately from bulk electrolyte. However, in some cases spectral resolution can limit the information that can be obtained. In this study we address this issue by showing how cross polarisation (CP) NMR experiments can be used to selectively observe the in-pore ions in supercapacitor electrode materials...
February 2018: Solid State Nuclear Magnetic Resonance
Gregory S Boutis, Ravinath Kausik
Quantitative evaluation of the solid and viscous components of unconventional shale rock, namely kerogen and bitumen, is important for understanding reservoir quality. Short transverse coherence times, due to strong1 H-1 H dipolar interactions, motivates the application of solid state refocusing pulse sequences that allow for investigating components of the free-induction decay that are otherwise obscured by instrumental effects such as probe ringdown. This work reports on static, wide-line1 H spectroscopy of shale rock and their extracted components, which include kerogen and bitumen, by the application of solid echo and magic echo pulse sequences...
November 2017: Solid State Nuclear Magnetic Resonance
Shigenobu Hayashi, Keiko Jimura
Inorganic solid acid salts with hydrogen bond networks frequently show very long spin-lattice relaxation times even for1 H because the hydrogen bonds suppress motions. In the present work, the1 H spin-lattice relaxation in Cs2 (HSO4 )(H2 PO4 ) containing a small amount of ammonium ions were studied in detail by use of the effect of magic angle spinning (MAS) on the relaxation. The1 H spin-lattice relaxation times of the acid protons decrease with increase in the content of ammonium ions. Reorientation of the NH4 group fluctuates the dipole-dipole interaction and relaxes the ammonium protons as well as the acid protons...
November 2017: Solid State Nuclear Magnetic Resonance
Patrick C A van der Wel
The aggregation of proteins and peptides into a variety of insoluble, and often non-native, aggregated states plays a central role in many devastating diseases. Analogous processes undermine the efficacy of polypeptide-based biological pharmaceuticals, but are also being leveraged in the design of biologically inspired self-assembling materials. This Trends article surveys the essential contributions made by recent solid-state NMR (ssNMR) studies to our understanding of the structural features of polypeptide aggregates, and how such findings are informing our thinking about the molecular mechanisms of misfolding and aggregation...
November 2017: Solid State Nuclear Magnetic Resonance
Marek J Potrzebowski
No abstract text is available yet for this article.
October 2017: Solid State Nuclear Magnetic Resonance
Jochem Struppe, Caitlin M Quinn, Manman Lu, Mingzhang Wang, Guangjin Hou, Xingyu Lu, Jodi Kraus, Loren B Andreas, Jan Stanek, Daniela Lalli, Anne Lesage, Guido Pintacuda, Werner Maas, Angela M Gronenborn, Tatyana Polenova
The recent breakthroughs in NMR probe technologies resulted in the development of MAS NMR probes with rotation frequencies exceeding 100 kHz. Herein, we explore dramatic increases in sensitivity and resolution observed at MAS frequencies of 110-111 kHz in a novel 0.7 mm HCND probe that enable structural analysis of fully protonated biological systems. Proton- detected 2D and 3D correlation spectroscopy under such conditions requires only 0.1-0.5 mg of sample and a fraction of time compared to conventional13 C-detected experiments...
October 2017: Solid State Nuclear Magnetic Resonance
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"