Characterization of the groove binding between di-(2-ethylhexyl) phthalate and calf thymus DNA.

In this study, the interaction between di-(2-ethylhexyl) phthalate (DEHP) and calf thymus DNA (ctDNA) was investigated by a combination of multispectroscopic methods, chemometrics algorithm, cyclic voltammetry and molecular simulation. The concentration profiles of the components obtained from resolving the UV-vis absorption data by multivariate curve resolution-alternating least-squares (MCR-ALS) provided a basic evidence for the formation of DEHP-ctDNA complex. Furthermore, the groove binding of DEHP to ctDNA was evidenced by the results from iodide quenching effect, single-stranded DNA quenching effect, melting studies, viscosity measurements and cyclic voltammetry. The binding constant of the complex was in the order of magnitudes of 10Lmol, and hydrophobic forces were inferred to drive the binding process. Analysis of Fourier transform infrared spectra suggested that DEHP preferentially bound to A-T rich region of ctDNA in the minor groove, and these results further confirmed by molecular docking. The circular dichroism spectra indicated that DEHP induced a decrease in base stacking degree and an increase in right-handed helicity of ctDNA, but did not cause a significant damage in DNA. This study may improve the understanding of interaction between DEHP and ctDNA and help evaluate the toxicological effect of DEHP.