Dynamics analysis of the backbone amide ^{15}N of (A*α*_{2}-L1M/L38M)_{2} in H_{2}O at 35°C. Longitudinal and transverse relaxation rate constants, *R*_{1} and *R*_{2}, and ^{15}N-{^{1}H} NOE values are shown in *A*, *B*, and *C*, respectively. The reduced spectral density functions, *J*(0), *J*(*ω*_{N}), and *J*(0.87*ω*_{H}), are shown in *D*, *E*, and *F*, respectively. *R*_{2}/*R*_{1} ratio and the correlation between *J*(*ω*_{N}) and *J*(0) and between *R*_{1} × *R*_{2} and *R*_{2}/*R*_{1} are shown in *G*, *H*, *I*, respectively. The relaxation data were acquired at 600 MHz. Error bars are either the standard errors in the least-squares fit to the exponential decay function (for *R*_{1} and *R*_{2}) or the calculated uncertainties (for NOE). (*H*) residues inside the dashed ellipse are from the loop region and the termini. The solid green curves describe the dependence of *J*(*ω*_{N}) on *J*(0) in the limiting case of single Lorentzian motion. Points to the right of the green curve suggest the presence of exchange and/or anisotropic contribution to the relaxation. (*I*) the contribution of exchange and anisotropy can be effectively isolated because the dependence of *R*_{1} × *R*_{2} on correlation times is greatly attenuated. Experimental data above the theoretical curve (*solid green curve*) suggest the presence of R_{ex} contribution to the R_{2} relaxation.

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