Figure 7.

¹⁹F spin exchange of 3F-Tyr-GB1. (a) GB1 structure (PDB: 2JSV⁶³) and the ¹⁹F isotropic chemical shifts. (b) ¹⁹F CP spectrum at 25 kHz MAS. Inset: isotropic peaks from the ¹⁹F CP spectrum (black) overlaid with the Y45 cross section (−132.9 ppm) of the 306 ms 2D CORD spectrum (red). (c) 2D ¹⁹F–¹⁹F correlation spectra with 77 ms (blue) and 306 ms (red) mixing. (d) Peak deconvolution of Y45 and Y3. (e) Normalized intensities of cross peaks and diagonal peaks as a function of mixing time. (f) ¹⁹F spin exchange time constants of –the three ¹⁹F sites for the ¹⁹F–¹⁹F distances in GB1. The distances are the average distances for 3-¹⁹F and 5-¹⁹F positions.