15N TROSY relaxation dispersion profiles for Arg-79 (A), Phe-225 (B), and Gly-138 (C) recorded at magnetic field strengths of 11.7 (●) and 18.8 (□) T, as a function of temperature. Arg-79, Phe-225, and Gly-138 are representative residues of Groups 1, 2, and 3, respectively.