scholarly journals Phospholipids in motion: High Resolution 31P NMR Field Cycling Studies

2021 ◽  
Author(s):  
Mary Roberts ◽  
Jingfei Cai ◽  
V.N. Sivanandam ◽  
Hanif M. Khan ◽  
Nathalie Reuter ◽  
...  
Keyword(s):  
High Resolution ◽  
High Field ◽  
Chemical Shift Anisotropy ◽  
Lateral Diffusion ◽  
Head Group ◽  
Polar Head Group ◽  
Field Range ◽  
Spin Lattice ◽  
Group Motion ◽  
Field Cycling

High resolution field cycling <sup>31</sup>P NMR spin-lattice relaxometry, where the sample is excited at high field, shuttled in the magnet bore for low field relaxation, then shuttled back to high field for readout of the residual magnetization, provides data on phospholipid dynamics and structure. In the field range from 11.74 down to 0.003 T three dipolar nuclear magnetic relaxation dispersions (NMRDs) and one due to <sup>31</sup>P chemical shift anisotropy contribute to R<sub>1 </sub>of phospholipids<sub>.</sub> Extraction of correlation times and maximum relaxation amplitudes for these NMRDs provides (1) lateral diffusion constants for different phospholipids in the same bilayer (illustrated with phospholipase C binding), (2) estimates of how additives alter the motion of the phospholipid about its long axis (looking at cholesterol effects), and (3) an average <sup>31</sup>P – <sup>1</sup>H angle with respect to the bilayer normal, which reveals that polar head group motion is not restricted on a µs timescale. Although this deals exclusively with phospholipids in small unilamellar vesicles, these same NMRDs can be measured for phospholipids in micelles and nanodiscs, making this technique useful for monitoring lipid behavior in a variety of structures.

scholarly journals Phospholipids in motion: High Resolution 31P NMR Field Cycling Studies

2021 ◽  
Author(s):  
Mary Roberts ◽  
Jingfei Cai ◽  
V.N. Sivanandam ◽  
Hanif M. Khan ◽  
Nathalie Reuter ◽  
...  
Keyword(s):  
High Resolution ◽  
High Field ◽  
Chemical Shift Anisotropy ◽  
Lateral Diffusion ◽  
Head Group ◽  
Polar Head Group ◽  
Field Range ◽  
Spin Lattice ◽  
Group Motion ◽  
Field Cycling

High resolution field cycling <sup>31</sup>P NMR spin-lattice relaxometry, where the sample is excited at high field, shuttled in the magnet bore for low field relaxation, then shuttled back to high field for readout of the residual magnetization, provides data on phospholipid dynamics and structure. In the field range from 11.74 down to 0.003 T three dipolar nuclear magnetic relaxation dispersions (NMRDs) and one due to <sup>31</sup>P chemical shift anisotropy contribute to R<sub>1 </sub>of phospholipids<sub>.</sub> Extraction of correlation times and maximum relaxation amplitudes for these NMRDs provides (1) lateral diffusion constants for different phospholipids in the same bilayer (illustrated with phospholipase C binding), (2) estimates of how additives alter the motion of the phospholipid about its long axis (looking at cholesterol effects), and (3) an average <sup>31</sup>P – <sup>1</sup>H angle with respect to the bilayer normal, which reveals that polar head group motion is not restricted on a µs timescale. Although this deals exclusively with phospholipids in small unilamellar vesicles, these same NMRDs can be measured for phospholipids in micelles and nanodiscs, making this technique useful for monitoring lipid behavior in a variety of structures.

scholarly journals Phospholipids in motion: High Resolution 31P NMR Field Cycling Studies

2021 ◽  
Author(s):  
Mary Roberts ◽  
Jingfei Cai ◽  
V.N. Sivanandam ◽  
Hanif M. Khan ◽  
Nathalie Reuter ◽  
...  
Keyword(s):  
High Resolution ◽  
High Field ◽  
Chemical Shift Anisotropy ◽  
Lateral Diffusion ◽  
Head Group ◽  
Polar Head Group ◽  
Field Range ◽  
Spin Lattice ◽  
Group Motion ◽  
Field Cycling

High resolution field cycling <sup>31</sup>P NMR spin-lattice relaxometry, where the sample is excited at high field, shuttled in the magnet bore for low field relaxation, then shuttled back to high field for readout of the residual magnetization, provides data on phospholipid dynamics and structure. In the field range from 11.74 down to 0.003 T three dipolar nuclear magnetic relaxation dispersions (NMRDs) and one due to <sup>31</sup>P chemical shift anisotropy contribute to R<sub>1 </sub>of phospholipids<sub>.</sub> Extraction of correlation times and maximum relaxation amplitudes for these NMRDs provides (1) lateral diffusion constants for different phospholipids in the same bilayer (illustrated with phospholipase C binding), (2) estimates of how additives alter the motion of the phospholipid about its long axis (looking at cholesterol effects), and (3) an average <sup>31</sup>P – <sup>1</sup>H angle with respect to the bilayer normal, which reveals that polar head group motion is not restricted on a µs timescale. Although this deals exclusively with phospholipids in small unilamellar vesicles, these same NMRDs can be measured for phospholipids in micelles and nanodiscs, making this technique useful for monitoring lipid behavior in a variety of structures.

scholarly journals Fast-field-cycling ultralow-field nuclear magnetic relaxation dispersion

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sven Bodenstedt ◽  
Morgan W. Mitchell ◽  
Michael C. D. Tayler
Keyword(s):  
High Resolution ◽  
Magnetic Relaxation ◽  
Magnetic Measurements ◽  
Nuclear Magnetic Relaxation ◽  
Relaxation Dispersion ◽  
Relaxation Rates ◽  
Field Range ◽  
Field Cycling ◽  
Fast Field ◽  
Nuclear Magnetic

AbstractOptically pumped magnetometers (OPMs) based on alkali-atom vapors are ultra-sensitive devices for dc and low-frequency ac magnetic measurements. Here, in combination with fast-field-cycling hardware and high-resolution spectroscopic detection, we demonstrate applicability of OPMs in quantifying nuclear magnetic relaxation phenomena. Relaxation rate dispersion across the nT to mT field range enables quantitative investigation of extremely slow molecular motion correlations in the liquid state, with time constants > 1 ms, and insight into the corresponding relaxation mechanisms. The 10-20 fT/$$\sqrt{{\rm{H}}}{\rm{z}}$$ H z sensitivity of an OPM between 10 Hz and 5.5 kHz 1H Larmor frequency suffices to detect magnetic resonance signals from ~ 0.1 mL liquid volumes imbibed in simple mesoporous materials, or inside metal tubing, following nuclear spin prepolarization adjacent to the OPM. High-resolution spectroscopic detection can resolve inter-nucleus spin-spin couplings, further widening the scope of application to chemical systems. Expected limits of the technique regarding measurement of relaxation rates above 100 s−1 are discussed.

Determination of chemical shift anisotropy tensor and molecular correlation time of proton pump inhibitor omeprazole by solid state NMR measurements

2020 ◽  
Vol 44 (44) ◽  
pp. 19393-19403
Author(s):  
Krishna Kishor Dey ◽  
Manasi Ghosh
Keyword(s):  
Correlation Time ◽  
Chemical Shift Anisotropy ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Structure And Dynamics ◽  
Molecular Correlation ◽  
Anisotropy Tensor

The correlation between the structure and dynamics of omeprazole is portrayed by extracting CSA parameters through the 13C 2DPASS CP-MAS SSNMR experiment, site specific spin–lattice relaxation time by Torchia CP experiment, and calculation of the molecular correlation time.

Phospholipids in Motion: High-Resolution 31P NMR Field Cycling Studies

2021 ◽  
Author(s):  
Mary F. Roberts ◽  
Jingfei Cai ◽  
Sivanandam V. Natarajan ◽  
Hanif M. Khan ◽  
Nathalie Reuter ◽  
...  
Keyword(s):  
High Resolution ◽  
31P Nmr ◽  
Field Cycling

scholarly journals How wide is the window opened by high-resolution relaxometry on the internal dynamics of proteins in solution?

2021 ◽  
Vol 75 (2-3) ◽  
pp. 119-131
Author(s):  
Albert A. Smith ◽  
Nicolas Bolik-Coulon ◽  
Matthias Ernst ◽  
Beat H. Meier ◽  
Fabien Ferrage
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
High Field ◽  
Rotational Diffusion ◽  
Relaxation Data ◽  
Internal Dynamics ◽  
Nmr Relaxometry ◽  
Analysis Of Dynamics

AbstractThe dynamics of molecules in solution is usually quantified by the determination of timescale-specific amplitudes of motions. High-resolution nuclear magnetic resonance (NMR) relaxometry experiments—where the sample is transferred to low fields for longitudinal (T1) relaxation, and back to high field for detection with residue-specific resolution—seeks to increase the ability to distinguish the contributions from motion on timescales slower than a few nanoseconds. However, tumbling of a molecule in solution masks some of these motions. Therefore, we investigate to what extent relaxometry improves timescale resolution, using the “detector” analysis of dynamics. Here, we demonstrate improvements in the characterization of internal dynamics of methyl-bearing side chains by carbon-13 relaxometry in the small protein ubiquitin. We show that relaxometry data leads to better information about nanosecond motions as compared to high-field relaxation data only. Our calculations show that gains from relaxometry are greater with increasing correlation time of rotational diffusion.

scholarly journals Molecular dynamics simulations and experimental studies reveal differential permeability of withaferin-A and withanone across the model cell membrane

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Renu Wadhwa ◽  
Neetu Singh Yadav ◽  
Shashank P. Katiyar ◽  
Tomoko Yaguchi ◽  
Chohee Lee ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Cell Membrane ◽  
Molecular Dynamics Simulations ◽  
Experimental Studies ◽  
Bilayer Membrane ◽  
Withaferin A ◽  
Head Group ◽  
Polar Head Group ◽  
Natural Drugs ◽  
Dynamics Simulations

AbstractPoor bioavailability due to the inability to cross the cell membrane is one of the major reasons for the failure of a drug in clinical trials. We have used molecular dynamics simulations to predict the membrane permeability of natural drugs—withanolides (withaferin-A and withanone) that have similar structures but remarkably differ in their cytotoxicity. We found that whereas withaferin-A, could proficiently transverse through the model membrane, withanone showed weak permeability. The free energy profiles for the interaction of withanolides with the model bilayer membrane revealed that whereas the polar head group of the membrane caused high resistance for the passage of withanone, the interior of the membrane behaves similarly for both withanolides. The solvation analysis further revealed that the high solvation of terminal O5 oxygen of withaferin-A was the major driving force for its high permeability; it interacted with the phosphate group of the membrane that led to its smooth passage across the bilayer. The computational predictions were tested by raising and recruiting unique antibodies that react to withaferin-A and withanone. The time-lapsed analyses of control and treated cells demonstrated higher permeation of withaferin-A as compared to withanone. The concurrence between the computation and experimental results thus re-emphasised the use of computational methods for predicting permeability and hence bioavailability of natural drug compounds in the drug development process.

A longitudinally detected high-field ESR spectrometer for the measurement of spin–lattice relaxation times

2004 ◽  
Vol 167 (2) ◽  
pp. 221-227 ◽  
Author(s):  
Ferenc Murányi ◽  
Ferenc Simon ◽  
Ferenc Fülöp ◽  
András Jánossy
Keyword(s):  
High Field ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
High Field Esr
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