Figure 3.

Folding free energy (in k_BT) for the three-way junction as a function of (A) Na⁺ concentration and (B) Mg²⁺ concentration (with 0.05M Na⁺ background), respectively. The experimental data are taken from the literature (22,25). In panel B, we use different ion radii for Mg²⁺ (4.5 Å, 3.5 Å, 2 Å, and 1 Å) to test the sensitivity of the PB predictions on the ion size. The dotted line is calculated from TBI without the excluded volume correlation.