FIGURE 7.

Comparison of ΔHs for duplex formation observed by ITC, DSC, and optical melting with those predicted from single strand melting alone. (A) Schematic of the calculation of ΔH^prcdict(T) from ΔH^dockand f^ΔH(T) as described in Materials and Methods; (B) duplex D-I at 1.0 M NaCl; (C) duplex D-V at 1.0 M added NaCl; (D) duplex D-I at 0.1 M added NaCl. In each case, the solid black line represents ΔH^prcdict = ΔH^dock + f^ΔH and turns into a dashed line at higher temperatures to indicate that reliable ITC data cannot be collected close to the T_M. Solid shapes represent experimental ΔHs from ITC (circles), optical melting (diamonds), or DSC (squares). Dotted lines represent extrapolations of ΔH(T) based on various estimates of ΔC_p: ITC ΔHs were extrapolated using ΔC_p^ITC; DSC ΔHs were extrapolated using ΔC_p^DSC; optical melting (UV) ΔHs were extrapolated using a constant 60 cal mol⁻¹ K⁻¹ bp⁻¹ estimate of ΔC_p.