title: Study on the Interaction between Isatin-β-Thiosemicarbazone and Calf Thymus DNA by Spectroscopic Techniques.
abstract: The interaction between isatin-β-thiosemicarbazone (IBT) and calf thymus DNA (CT-DNA) was investigated in physiological buffer (pH 7.4) using Neutral Red (NR) dye as a spectral probe by UV-Vis absorption and ﬂuorescence spectroscopy, as well as viscosity measurements. The IBT is stabilized by intercalation in the DNA (K [IBT -DNA] = 1.03×10(5) M(-1)), and displaces the NR dye from the NR-DNA complex. The binding constants Kf and number of binding sites (n≈1) of IBT with DNA were obtained by fluorescence quenching method at different temperatures. Furthermore, the enthalpy and entropy of the reaction between IBT and CT-DNA showed that the reaction is enthalpy-favored and entropy-disfavored. The changes in the base stacking of CT-DNA upon the binding of IBT are reflected in the circular dichroic (CD) spectral studies. The viscosity increase of CT-DNA solution is another evidence to indicate that, IBT is able to be intercalated in the DNA base pairs.
authors.affiliation: Department of Chemistry, Zanjan Branch, Islamic Azad University, Zanjan, Iran.
authors.forename: Parvaneh
authors.initials: P
authors.lastname: Pakravan
authors.affiliation: Department of Chemistry, Payame Noor University, I.R. of Iran.
authors.forename: Shahla
authors.initials: S
authors.lastname: Masoudian
keywords: CT-DNA; Intercalation; Isatin-β-thiosemicarbazone; Neutral Red dye