A. Krushelnitsky, T. Zinkevich, B. Reif, K. Saalwächter.
Slow motions in microcrystalline proteins as observed by
MAS-dependent 15N rotating-frame NMR relaxation.
J. Magn. Reson. 248, 8-12 (2014).
15N NMR relaxation rate R1ρ measurements reveal that a substantial fraction of residues in the microcrystalline chicken alpha-spectrin SH3 domain protein undergoes dynamics in the ls–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 R1ρ’s in proton-diluted protein samples are practically free from the coherent
spin–spin contribution even at low MAS rates, and thus can be analysed 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 R1ρ experiments.