Figure 5.

(a) Schematic of the modified G16⋅G22⋅G4⋅G10 tetrad is presented with the G_α⋅G_β⋅G_γ⋅G_δ naming convention. Special attention is brought to the hydrogen bonds of the G_δ⋅G_α interface. (b–e) The NMR imino proton spectrum of (b) the unmodified sequence is presented along with the spectra of (c) Br-16, (d) Omet-16, and (e) Am-16. The chemical shift of the imino proton peak from the G_δ residue, G10, in the unmodified sequence is indicated by the dotted black line. Arrows indicate the positions of the G_δ imino proton peaks in the modified spectra. (f) Example of the unambiguous G10 imino proton assignment for Omet-16 using ¹⁵N-labeling.