Figure 21.

Variation of R₂ + R_ex during off-resonance R_1ρ experiments, for a wide range of k_ex and p_ES values for two-state exchange, simulated using the B-M equations. Horizontal comparisons show changes in k_ex while vertical comparisons show changes in p_ES. Different spin-lock amplitudes are denoted by colors. Dotted lines correspond to cases where the decay of the magnetization is not mono-exponential. Solid gray vertical lines correspond to an offset of –Δω, while the yellow star denotes a typical Watson-Crick to Hoogsteen exchange scenario in DNA[115]. Simulations assumed the following parameters: $\Delta \overline{\omega }{(}^{13}\text{C)}=3\text{\hspace{0.17em}ppm}$, γ(¹H)B₀/2π = 700 MHz, R_1,GS = R_1,ES = 2.5 s ⁻¹ and R_2,GS = R_2,ES = = 22.5 s⁻¹. The initial alignment of the magnetization was performed as described in Section 6.1.