Characterization of fibril dynamics on three timescales by solid-state NMR

A multi-timescale analysis of the backbone dynamics of HET-s (218-289) fibrils is described based on multiple site-specific R-1 and R-1 rho data sets and S-2 measurements via REDOR for most backbone N-15 and C-13 alpha nuclei. N-15 and C-13 alpha data are fitted with motions at three timescales. Slow motion is found, indicating a global fibril motion. We further investigate the effect of C-13-C-13 transfer in measurement of C-13 alpha R-1. Finally, we show that it is necessary to go beyond the Redfield approximation for slow motions in order to obtain accurate numerical values for R-1 rho.