Expansions of the aliphatic region of (a) IL-bo3, (b) IY-bo3 and (c) HY-bo3, and aromatic region of (d) IY-bo3 and (e) HY-bo3. 13C-13C 2D spectra were collected on a 600 MHz spectrometer (1H frequency) with 50 ms DARR mixing. Data were acquired for 160, 96 and 120 hrs for the IL-, IY-, and HY-bo3 samples, respectively, and processed with 40 Hz (F1) and 40 Hz (F2) net Gaussian-to-Lorentzian line broadening. Dashed lines highlight the spin systems of residues in common between the samples (Ile and Tyr).