*4.5. Interproton Distance Determination via NOE Integration*

The NOE cross-peaks for all peptides were assigned from the corresponding ROESY spectra. Integration was performed based on Gaussian peak modeling to obtain the intensity of cross-peaks (I). The distance between the β-hydrogen atoms on the proline side-chain (regardless of stereochemistry) was set as the standard (1.77 Å) to derive the interproton distance for the cross-peak of interest using Equation (4). The distances (r) were grouped into short (≤2.5 Å), medium (2.5~3.5 Å), and long (>3.5 Å) for the depictions in the Wüthrich diagrams (Figures S39–S50).

$$\mathbf{r} = 1.77 \times 10^{-10} \times \left(\frac{\mathbf{I}\_{\text{standard}}}{\mathbf{I}\_{\text{NOE}}}\right)^{\frac{1}{6}} \tag{4}$$
