Figure 7.

Hydration of the W41F AM2-TM channel probed by 2D ¹H-¹³C correlation spectra. (a) Cα S/S₀ values of W41F M2. (b) Cα S/S₀ values of WT M2. (c) Cβ S/S₀ values of W41F M2. (d) Cβ S/S₀ values of WT M2. Green squares, red diamonds, and black circles represent low pH, drug-bound low pH, and high pH data, respectively. Open symbols indicate values with greater uncertainty. Dashed green and black lines indicate the mean S/S₀ value for low and high pH, respectively. The W41F mutant has lower average hydration than the WT channel at high pH and similar average hydration as the WT at low pH. However, the C-terminus of the WT peptide is less hydrated than the N-terminus at low pH, while the W41F mutant shows similar hydration of the two termini at low pH.