Results in Fig. attempt to conclude that effective correlation times can be directly derived from R • 2 values using the first term of Eq. 5, denoted here as the linear approximation. However, more detailed comparison in Fig. shows that the linear approximation slightly overestimates effective correlation times that are smaller than approximately 3 ns, in line with supplementary figure showing magnitudes of different terms in Eq. 5. On the other hand, the 1-timescale approximation gives slightly better results for the fast timescales. The blue-shaded regions in Fig. show the numerically solved possible range of effective time values that can appear for the given R • 2 . In conclusion, linear approximation sets the upper limit for possible τ eff values corresponding to a given R • 2 value, while 1-timescale approximation sets the lower limit for τ eff values of residues with rapid rotations and asymptotically approaches the linear approximation for longer timescales.