Data processing were done by JEOL Delta software for 1D data and NMRPipe for otherwise. The exponential and Lorentz-to-Gauss window functions were applied to the 1D and 3D data, respectively, prior to the zero-filling and Fourier transformation. Spectral analyses were performed by NMRFAM-Sparky 36 and POKY . The resonance assignments of GB1 were taken from BMRB 15156 and adapted using CANH, CAcoNH and caCBcaNH spectra (Table ). The spectra were visualized by Python with Nmrglue 38 and Matplotlib packages .