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Published on: July 4, 2016
Suppression of ghost distances in multiple-spin double electron-electron resonance
Tona von Hagens1, Yevhen Polyhach, Muhammad Sajid
1ESR Group, Laboratory of Physical Chemistry, Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland.
Physical Chemistry Chemical Physics : PCCP
|March 15, 2013
Summary
Ghost contributions in double electron-electron resonance experiments can obscure true interspin distances. A new power scaling method effectively suppresses these artifacts, improving distance measurements in multiple-spin systems.
Area of Science:
- Biophysics
- Spectroscopy
- Computational Chemistry
Background:
- Pulse electron paramagnetic resonance (Pulsed EPR) techniques are vital for measuring distances in biological systems.
- Multiple-spin systems in double electron-electron resonance (DEER) experiments can introduce 'ghost' peaks, complicating accurate distance determination.
- These ghost contributions arise from complex dipolar frequency interactions and can mislead analysis by appearing as real distances or distorting actual peaks.
Purpose of the Study:
- To develop a straightforward method for suppressing ghost contributions in DEER experiments.
- To enhance the accuracy and reliability of interspin distance measurements in systems with more than two spins.
- To enable routine application of accurate distance measurements to complex biological systems.
Main Methods:
- A novel data analysis approach involving power scaling of the experimentally obtained form factor is introduced.
- The scaling exponent ζ(N) = 1/(1-N) is utilized, where N represents the number of coupled spins.
- The method was validated using simulated data for up to five spins and applied to synthetic model samples.
Main Results:
- The power scaling method significantly suppresses prominent ghost contributions in distance distributions.
- Accurate distance measurements are achieved without additional experimental effort or precise knowledge of labelling/inversion efficiencies.
- The approach demonstrates best performance for symmetric geometries and rigid molecules, where ghost artifacts are most problematic.
- Obtained distance distributions align well with those from previous methods and expected true interspin distances.
Conclusions:
- The presented power scaling technique offers an effective and simple solution for mitigating ghost contributions in DEER spectroscopy.
- This method enhances the precision of distance measurements in multi-spin systems, crucial for structural biology.
- The approach facilitates more reliable structural insights from Pulsed EPR studies on complex biological molecules.
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