FIGURE 7.

Correlation diagram of R_ex and ΔR_ex at 600 MHz. The exchange lifetime scatter around ≈ 50 μs. The R_ex and ΔR_ex show a linear dependence given the exchange time according to fast exchange limit (Eqs. 3 and 4) (solid lines) and according to the approximate function (Eq. 6) (within 15%), proposed by Ishima and Torchia (34), which applies over all timescales provided p_A ≫ p_B (dashed lines). In these calculations of theoretical R_ex and ΔR_ex correlations, the CPMG delay, δ₁ and δ₂ were set to their experimental values, Δ_ex ranges from 0 to 6 ppm to cover the relevant range, ω_I to its corresponding value (Δ_exω_I is maximum 2100 s⁻¹), p_A is taken for convenience equal to 0.5 for the fast exchange limit calculations (solid lines) and equal to 0.9 for the general equation (dashed lines). Both equations show similar correlation lines given this range of parameter values.