Related Experiment Video
Updated: Jun 4, 2025
05:51
Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
6.2K
Analysis of the MODIST Sequence for Selective Proton-Proton Recoupling.
Evgeny Nimerovsky1, Marianna Stampolaki1, Abel Cherian Varkey1
1Department of NMR based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, Göttingen 37077, Germany.
The Journal of Physical Chemistry. A
|December 23, 2024
Summary
We introduce MODIST, a selective dipolar recoupling sequence, and discover facilitated dipolar recoupling, enhancing polarization transfer between spins. This method aids in analyzing complex molecules like membrane proteins without labeling.
Area of Science:
- Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy
- Advanced pulse sequence development
- Biomolecular structure determination
Background:
- Selective homonuclear dipolar recoupling sequences are crucial for understanding spin dynamics in NMR.
- Evaluating sequence robustness under varying conditions is essential for reliable data acquisition.
- The MODIST (Modest Offset Difference Internuclear Selective Transfer) sequence is a recent advancement in first-order dipolar recoupling.
Purpose of the Study:
- To investigate the efficiency and robustness of the MODIST sequence.
- To explore the dependence of MODIST performance on radiofrequency (rf) field strengths and spin system size.
- To identify conditions that enhance polarization transfer, particularly for spins with close frequencies like aliphatic protons.
Main Methods:
- Theoretical and simulated analyses of the MODIST sequence.
- Evaluation of transfer efficiency with up to 10 simulated spins.
- Experimental validation using the membrane protein influenza A M2 in lipid bilayers.
- Magic-angle spinning (MAS) NMR experiments at 55 kHz.
Main Results:
- MODIST transfer efficiency was assessed across various rf-field strengths and spin numbers.
- A novel 'facilitated dipolar recoupling' effect was discovered, amplifying interactions between distant spins.
- This effect requires coupling to only one of the two distant spins, differentiating it from other mechanisms.
- Experimental demonstration on influenza A M2 confirmed MODIST performance at different rf-field strengths.
Conclusions:
- The MODIST sequence is effective for selective homonuclear dipolar recoupling.
- Facilitated dipolar recoupling offers a new mechanism to enhance spin interactions.
- Reducing rf-field strength with MODIST enables detection of specific correlations (Hα-Hα, HMeth-HMeth) in complex systems like membrane proteins under fast MAS, without isotopic labeling.
More Related Videos
10:52Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
2.7K
14:55Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
15.4K
Related Concept Videos
01:12Double Resonance Techniques: Overview
191
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
191
01:13¹H NMR: Complex Splitting
1.2K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.2K
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
1.0K
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
1.0K
01:04¹³C NMR: ¹H–¹³C Decoupling
1.0K
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
1.0K
01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
1.1K
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the...
1.1K
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
232
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
232