Table 3. Comparison of thermodynamic parameters for chartreusin binding to salmon testes DNA^a.

	Kobs (M–1)	ΔGobs (kcal/mol)	–SK	ΔGpe (kcal/mol)	ΔGt (kcal/mol)	ΔHb (kcal/mol)	TΔS (cal/mol)
Chartreusin	3.6 × 105	–7.4	0.13	–0.3	–7.1	–7.1 (± 0.2)	0.4

^aK_obs (M^–1) is the binding constant for the interaction of the ligand with salmon testes DNA in 18 mM Na⁺ at 20°C. ΔG_obs is the binding free energy calculated from ΔG_obs = –RT lnK. SK is the slope of the plot of logK_obs versus log[Na⁺] shown in Figure 5A. ΔG_pe and ΔG_t are the polyelectrolyte and non-polyelectrolyte contributions to the binding free energy (ΔG_pe = SK RT ln[Na⁺]) evaluated at 18 mM Na⁺. ΔH_b was determined by ITC at 20°C (see Table 1).