The BE pulse length was set to 2 ms; it is composed of a series of 2 µs rectangular pulses, and optimized for obtaining a steep edge profile of the selective Cβ inversion. The phase and intensity of each element pulse were optimized by the GRAPE algorithm as described in the supporting information, and the obtained pulse shapes are illustrated in Figure . The Cβ chemical shifts of Ser and Thr residues (> 60 ppm) overlap with the Cα chemical shift range, and always inverted in the above design, thus they are supposed to be invisible in the BE-experiments. Cys Cβ chemical shifts are strongly affected by the disulfide bond formation, and are not considered in this method. The cost we pay for implementing the BE approach is the measurement time for the four 3D experiments (reference data and data with BE-1/2/3 pulse), which is the same time to measure two complex points when the Cβ chemical shift is explicitly evolved. It is impossible to discriminate the amino acid groups defined above from the two points measurement. Thus, the cost is tolerated when the explicit Cβ chemical shift encoding or the 4D measurements are prohibitive. First of all, we checked the designed BE pulses in simulation. Figure shows the inversion profiles simulated for 𝐼 ! , 𝐼 # and 𝐼 " using the BE-1/2/3 pulses. It can be seen in the Cα region ([50, 80] ppm), the 𝐼 ! magnetizations are intact while the 𝐼 # and 𝐼 " magnetizations are inverted, being equivalent to an 𝑥 -phase 180° pulse for Cα spins. The C' longitudinal magnetization always remains intact, allowing to avoid the Cα-C' scalar-couplings to disturb the 𝐶𝛼 ! → 2𝐶𝛼 # 𝐶𝛽 " transition of interest. Finally, it can be seen that the 𝐼 " inversion profiles in the Cβ region conforms to the above design. While we designed the BE-1/2/3 pulses for the use at B0 = 16.4 T ( 1 H Larmor frequency of 700 MHz), a simple scaling of the RF power and pulse duration maintains the inversion profiles for the use at other field conditions (Figure ).