Slow motions in microcrystalline proteins as observed by MAS-dependent 15N rotating-frame NMR relaxation
Publication date: Available online 20 September 2014
Source:Journal of Magnetic Resonance
Author(s): Alexey Krushelnitsky , Tatiana Zinkevich , Bernd Reif , Kay Saalwächter
15N NMR relaxation rate R 1? measurements reveal that a substantial fraction of residues in the microcrystalline chicken alpha-spectrin SH3 domain protein undergoes dynamics in the ?s - ms timescale range. On the basis of a comparison of 2D site-resolved with 1D integrated 15N spectral intensities, we demonstrate that the significant fraction of broad signals in the 2D spectrum exhibits the most pronounced slow mobility. We show that 15N R 1?’s in proton-diluted protein samples are practically free from the coherent spin-spin contribution even at low MAS rates, and thus can be analyzed quantitatively. Moderate MAS rates (10-30 kHz) can be more advantageous in comparison with the rates >50-60 kHz when slow dynamics are to be identified and quantified by means of R 1? experiments.
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