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SSNMR Measurements & Methods

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SSNMR Methods & Measurements

Magic angle spinning (MAS) NMR methods have the demonstrated ability to measure distances between atoms (nuclei) as well as a variety of angular constraints (e.g. peptide bond and side chain torsion angles). These methods were initially developed and demonstrated in test samples, such as small peptide crystals and model proteins, but are increasingly applied to a wide range of proteins. The measurement of ¹³C-¹³C distances via R² width methods [1,2]  is but one example of an increasingly versatile array of distance and torsion angle measurements. Macroscopically aligned lipid bilayer samples allow other approaches, in particular measurements that allow determination of the orientation (and motion) of  proteins or peptides relative to the membrane, such as transmembrane helix tilt and tryptophan interfacial anchors  [3 - 5].

The weak point of most NMR methods is the relatively low sensitivity of the method, compared to other biophysical techniques. The results in the requirements for relatively large sample sizes and long acquisition times. Ongoing develpments on the hardware and methodology aim at substantial sensitivity improvements, for example through the application of dynamic nuclear polarization (DNP) methods [6]. See also this page.

References

1. Ramachandran, R. et al . (2006) "Multipolemultimode Floquet theory of rotational resonance width experiments: ¹³C-¹³C distance measurements in uniformly labeled solids." J. Chem. Phys. 124: 214107 *
2. Van der Wel, P.C.A. et al. (2009) Targeted ¹³C-¹³ Distance Measurements in a Microcrystalline Protein via J-Decoupled Rotational Resonance Width Measurements. ChemPhysChem 10 (9-10): 1656-1663 DOI
3. Van der Wel, P. C. A. et al.. (2002) "Geometry and intrinsic tilt of a tryptophan anchored transmembrane alpha-helix determined by ²H NMR." Biophys. J. 83, 1479-1488 *
4. Koeppe, R.E., II et al. (2003) "Combined experimental/theoretical refinement of indole ring geometry using deuterium magnetic resonance and ab initio calculations." J. Am. Chem. Soc. 125: 12268-12276. *
5. Van der Wel, P.C.A. et al. (2007) "Orientation and motion of tryptophan interfacial anchors in membrane-spanning peptides." Biochemistry 46(25):7514-24  
6. Van der Wel, P.C.A. et al. (2006)  "Dynamic nuclear polarization of amyloidogenic peptide nanocrystals: GNNQQNY, a core segment of the yeast prion protein Sup35p." J. Am. Chem. Soc. 128:10840-10846 *