Figure 8.

(A) Imino proton region of Tel26 in K⁺ solution in a variable temperature study. As seen above 65°C there is no detectable peak intensity in the imino (exchangeable proton) region. The imino protons are labeled on the spectrum recorded at 20°C. (B) D₂O-to-H₂O NMR exchange experiments. The imino region of the 1D ¹H NMR spectrum of Tel26, which was first incubated overnight in 99.96% D₂O and then incubated in H₂O for 30 min, 3.5 h and then overnight at 25°C. Imino protons from the middle layer of the G-tetrad (Figure 5) are the last to appear and are labeled with the residue numbers. (C) Melting profile of Tel26 in K⁺ solution in a CD variable temperature study. The same melting temperature of 55°C is shown by both CD and NMR (A).