Figure 3.

Cross-sections through the spectra of Fig. 2 (solid lines). To facilitate a comparison of the linewidths in the different spectra the cross-sections were normalized to the same maximal signal amplitude. (a1), (a2), etc. refer to the arrows in Fig. 2. Simulated line shapes (dashed lines in a and b) were calculated using ¹J(¹H,¹⁵N) = −105 Hz, a rotational correlation time of τ_c = 20 ns, and chemical shift anisotropies of Δσ_H = −16 ppm and Δσ_N = −160 ppm. A long-range scalar coupling ²J(¹H^δ1,¹⁵N^ɛ1) = −5 Hz was included in the simulation of the ¹⁵N lineshapes (24), but possible effects of the small scalar couplings ³J(¹H^δ1,¹H^ɛ1) and ³J(¹H^ζ2,¹⁵N^ɛ1) were neglected. For ¹H^N the relaxation due to DD coupling with other protons in the nondeuterated complex was approximated by three protons placed at a distance of 0.24 nm from ¹H^N.