Figure 4.

Formation of GQS RNA oligonucleotides (a) CD spectra of RNA GQS in 10 mM LiCacodylate (pH 7.0) and 150 mM KCl at 20°C: G₃L₂₂₁ (black), G₂L₁₁₁ (red), G₃L₄₄₄ (gold), G₃L₄₄₄ + FLANK (green) and G₂L₄₄₄ (blue). The positive peak at 260 nm and the negative peak at 240 nm suggest that the RNA GQS adopt a parallel conformation. The G₂L₁₁₁ RNA most likely has some antiparallel character due to the shoulder in the spectrum extending to 300 nm. See ‘Materials and Methods’ section for full sequences. (b) Sample K⁺ titration. Titration is of G₃L₄₄₄ RNA GQS with KCl additions from 0 mM to 700 mM. The arrows indicate increasing K⁺ concentrations. Also included are UV thermal denaturations of G₃L₄₄₄ RNA in 100 mM LiCl (black), NaCl (red) and KCl (blue) at (c) 260 nm and (d) 295 nm. Absorbances are normalized to the highest absorbance.