Spectrophotometric Studies on the Thermodynamics of the ds-DNA Interaction with Irinotecan for a Better Understanding of Anticancer Drug-DNA Interactions

Table 2

Hypochromicity (𝐻), total equilibrium binding constant (𝐾_𝑏), nonelectrostatic equilibrium binding constant (𝐾⁰_𝑡), and ratio of 𝐾⁰_𝑡 to 𝐾_𝑏 at various salt concentrations.

[K^+] (mol L^−1)	𝐻 (%)	𝐾𝑏 (L mol^−1)	𝐾^0𝑡 (L mol^−1)	𝐾^0𝑡/𝐾𝑏(%)
0.01	8.21	6.37 × 10^4	8.81 × 10^2	1.38
0.02	7.24	3.06 × 10^4	8.90 × 10^2	2.91
0.05	6.27	2.56 × 10^4	9.06 × 10^2	3.53
0.10	5.74	4.90 × 10^3	9.22 × 10^2	18.81