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2H[19F] REDOR for distance measurements in biological solids using a double resonance spectrometer
Stephan L Grage1, Jude A Watts, Anthony Watts
1Biomembrane Structure Unit, Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU, Oxford, UK.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|December 17, 2003
Summary
This study introduces a novel 2H[19F] rotational echo double resonance (REDOR) method for measuring distances in biological solids. The technique enables accurate distance determination without specialized fluorine equipment, benefiting structural biology.
Area of Science:
- Biophysical Chemistry
- Structural Biology
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Distance measurements are crucial for understanding molecular structure and function in biological systems.
- Conventional methods may require specialized equipment or lack sufficient distance range.
Purpose of the Study:
- To develop and validate a new 2H[19F] rotational echo double resonance (REDOR) approach for distance measurements in biological solids.
- To demonstrate the utility of this method without 1H decoupling, leveraging fluorine's longer distance range.
Main Methods:
- Utilized 2H[19F] rotational echo double resonance (REDOR) experiments without 1H decoupling.
- Employed a double resonance NMR spectrometer for measurements.
- Validated the method on 2H,19F-D-alanine and an imidazopyridine-based H+/K+-ATPase inhibitor.
Main Results:
- Measured a distance of 2.5 ± 0.3 Å in the D-alanine derivative, indicating a gauche conformation.
- Determined a lower distance limit of 5.2 Å for the imidazopyridine compound, consistent with an extended conformation.
- Demonstrated enhanced frequency bandwidth and reduced transmitter frequency dependence using composite fluorine dephasing pulses.
Conclusions:
- The developed 2H[19F] REDOR method provides a valuable tool for distance measurements in biological solids.
- The approach offers a cost-effective alternative by avoiding specialized fluorine NMR equipment.
- Optimized REDOR variants and pulse sequences improve experimental performance and applicability.