Figure 3.

¹H-NMR spectra and proposed models of structures adopted by r(G₄C₂)₄. (a) ¹H-NMR spectrum of r(G₄C₂)₄ in 10% ²H₂O at pH 6.0, 25 °C and 0.9 mM oligonucleotide concentration per strand. Schematic presentation of (b) homodimer and (c) hairpin adopted by r(G₄C₂)₄. (d) Imino regions of ¹H-NMR spectra of r(G₄C₂)₄ in 10% ²H₂O at different concentrations of K⁺ ions. KCl solution was gradually titrated into the sample up to the stated concentration of K⁺ ions, displayed on the left of the NMR spectra. Δ represents NMR spectrum after annealing while t on the right represents time after each addition of K⁺ ions until acquisition of NMR spectrum. All spectra were acquired at 25 °C, pH 6.0 and 0.2 mM oligonucleotide concentration per strand.