Figure 7.

Overall stability, stacking and base pairing contributions for DNA polymers at different salt conditions. (a) Salt dependence of the stacking term in the stability of A•T- (red circles) and G•C- (blue circles) containing polymers. Straight solid lines of the same color correspond to the salt dependence of the DNA polymer stability calculated using Equations 5 and 6 at 37°C. (b) Salt dependence of the base pairing parameters for A•T (red) and G•C (blue) pairs calculated at each concentration as a difference between stability term and stacking term using data from (a). Horizontal broken lines correspond to mean values of $\Delta G_{\text{A}•\text{T}}^{\text{BP}}=0.61\text{kcal}/\text{mol}$ and $\Delta G_{\text{G}•\text{C}}^{\text{BP}}=-0.01\text{kcal}/\text{mol}$.