Thermodynamic characterization of daunomycin-DNA interactions: Comparison of complete binding profiles for a series of DNA host duplexes

Using a combination of spectroscopic and calorimetric techniques, we have determined complete thermodynamic binding profiles (ΔG o , ΔH o , and 45 o ) for the complexation of daunomycin to a series of 10 polymeric DNA duplexes. We find the resulting drug binding data to be sensitive to the base composition and sequence of the host duplex, with the binding free energies ranging from -7.5 to -10.8 kcal/mol of bound drug and the binding enthalpies ranging from +4.11 to -10.76 kcal/mol of bound drug at 25 o C. The smaller range in the free energy term reflects the impact of large enthalpy-entropy compensations