To investigate the influence of chemical exchange on magnetic field dependence of effective correlation time, we calculated τ eff values with the chemical exchange correction using Supplementary Eq. S17 and available experimental R2 values at different fields for CsPinA (Fig. ) and B3 Figure . Effective correlation times calculated using linear approximation for all proteins with R 2 values available in 4 different magnetic fields in BMBR database : Azurin (BMBR: 6243 , PDB: 1AZU ), B3 domain of protein G (BMBR: 26845 , PDB: 1IGD ), human apo S100A1 (BMRB: 16360, PDB: 2L0P ), and CsPinA Parvulin (BMRB: 18864 , PDB: 2M1I) Protein structures are taken from the protein data bank (PDB) . Data points and structures are labeled with the same color for each protein. The black lines show equal values with both magnetic fields.