Figure 9.

Comparison of MQ CSM(¹⁵N)/CSM(¹H) CCR rates and SQ ¹⁵N exchange contribution. The dependence of ΔR^MQ(exchange) = 2R_{CSM(15N)/CSM(1H)} rates upon the exchange time scale, k_ex = 1/τ_ex, and the ¹H and ¹⁵N chemical shift modulations, Δω_H and Δω_N, respectively, is shown with the thin curves calculated from equation 8 in the study by Wang and Palmer^[93] (Δω_N = 2 ppm at 600 MHz, p₁ = 0.9 and Δω_H/Δω_N ratios equal to 0.2, 0.5, 1,2, 5). The plotted results would be multiplied by −1 if Δω_H and Δω_N had opposite signs. The bold curve shows the exchange contribution to SQ ¹⁵N relaxation, R_ex plotted versus log(k_ex/Δω_N). Reprinted by permission from Springer Nature: C. Wang, A.G. Palmer III, Differential multiple quantum relaxation caused by chemical exchange outside the fast exchange limit. J. Biomol. NMR, 2002, 24, 263–268, copyright 2002.