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Intensity and mosaic spread analysis from PISEMA tensors in solid-state NMR
J R Quine1, S Achuthan, T Asbury
1Department of Mathematics, Florida State University, Tallahassee, FL 32306-4510, USA. quine@math.fsu.edu
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|January 18, 2006
Summary
This study introduces a method using the solid-state NMR experiment PISEMA to determine protein structures. It analyzes how peptide plane orientations affect spectral lineshapes, providing an orientational error bar for structural analysis.
Area of Science:
- Biophysics
- Structural Biology
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Solid-state NMR, specifically the PISEMA experiment, is crucial for protein structure determination, especially for membrane proteins in oriented samples.
- Determining protein structure involves finding the orientation of local molecular frames, such as peptide planes, relative to the magnetic field (B0).
Purpose of the Study:
- To analyze the PISEMA function and its degeneracies to understand peptide plane orientations.
- To derive a formula for the intensity function in the powder pattern to measure sensitivity of orientations to data.
- To investigate the impact of small changes in peptide plane orientations on spectral lineshapes and interpret these as orientational error bars.
Main Methods:
- Analysis of the PISEMA function and its inherent degeneracies.
- Derivation of an intensity function formula for powder patterns.
- Investigation of resonance location effects on spectral lineshapes and sensitivity.
Main Results:
- A formula for the intensity function was derived, quantifying the sensitivity of peptide plane orientations to experimental data.
- The study revealed how small changes in peptide plane orientations influence resonance positions within the powder pattern spectrum.
- The relationship between spectral lineshape changes, mosaic spread, and orientational error bars was established.
Conclusions:
- The derived intensity function provides a quantitative measure for assessing the orientational error in protein structure determination using PISEMA.
- Understanding the sensitivity of peptide plane orientations to spectral features allows for more accurate structural interpretation.
- This work offers a refined method for interpreting PISEMA data, enhancing the precision of structural analysis for oriented protein samples.
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