Fig. 2.

Simulated inversion profiles of a hard and G5 π pulses for ¹H (A), ¹⁵N (B), and ¹³C (C) on an 850 MHz spectrometer. The simulated curves were obtained using the ‘shapetool’ in the Bruker software. The durations of G5 pulse is ten times longer than a hard π/2 pulses (Note that the durations of hard π/2 pulses for the ¹H, ¹⁵N and ¹³C are 14.4, 32.0 and 11.2 μs, respectively). The spectral widths indicated in the axis are those commonly used for biomacromolecules (11, 36, and 60 ppm for ¹H, ¹⁵N and ¹³C dimensions). Note that the G5 pulse uniformly excites 23.5, 105, and 116 ppm for ¹H, ¹⁵N and ¹³C, respectively.