Comprehensive Study on the Binding of Iron Schiff Base Complex with DNA and Determining the Binding Mode

Abstract

The iron (III) [N, N' Bis (5-(triphenyl phosphonium methyl) salicylidene)-1, 2 ethanediamine] chloride [Fe Salen]Cl, has been synthesized and characterized as described previously. The interaction of iron complex with calf thymus (CT) DNA has been studied extensively by experimental techniques. Absorption spectra showed both hypochromism and hyperchromism. Thermal denaturation study of DNA with complex revealed the ΔTm of 5 °C. Competitive binding study shows that the enhanced emission intensity of ethidium bromide (EB) in the presence of DNA was quenched by adding of the iron complex indicating that it displaces EB from its binding site in DNA and the apparent binding constant has been estimated to be 5 × 10(6) μM(-1). Fluorescence Scatchard plot revealed type B behavior for interaction of complex to DNA. Circular dichroism (CD) spectra measurements showed that the complex interacts with DNA via surface and groove bindings. Linear dichroism (LD) measurements confirmed the bending of DNA in the presence of complex. Furthermore, Isothermal titration calorimetry (ITC) experiments approved that the binding of complex is based on both electrostatic and hydrophobic interactions. More, ITC profile exhibits the existence of two binding phases for the complex.

Photoactivation of the Cytotoxic Properties of Platinum(II) Complexes through Ligand Photoswitching

“…38 Due to the trans-disposition of the chlorides, it is expected that each platinum ion will mostly produce 3-intrastand cross-links and monofunctional adducts, which will undergo conversion to interstrand cross-links; 39 It can be noticed that the quenching effect is clearly more pronounced for closed C1 than for open C1 (Figure 3), hence suggesting that the closed photoisomer has a higher capacity to expel DNA-bound EB, and thus confirming its better intercalating properties (see gel electrophoresis results). 45 To properly compare the DNA affinity of all studied species, the fluorescence emission data obtained were used to determine the corresponding Stern-Volmer quenching constants (KSV) for intermolecular deactivations, by applying the Stern-Volmer equation 1: 46…”

Highly cytotoxic DNA-interacting copper(ii) coordination compounds

“…63,64 Hence, displacement of EB through the binding of a molecule to DNA will result in fluorescence quenching, therefore providing valuable information regarding the DNA affinity of the compound considered. 65,66 It should be stated here that EB displacement by the molecule studied does not imply that it acts as an intercalator (like EB). Indeed, electrostatic interactions or groove binding may be sufficient to alter significantly the conformation of the DNA double helix, inducing the release of EB.…”

Synthesis, characterization, molecular modeling, and DNA interaction studies of a Cu(II) complex containing drug of chronic hepatitis B: adefovir dipivoxil

“…Binding of a complex with DNA via intercalation generally results in hypochromism and a red-shift of the absorption band (bathochromic effect) because of strong interaction between the ligand and the base pairs of the DNA [37,38]. In groove binding between DNA and small molecules, hyperchromism can be observed, while the position of the absorption almost does not change, which can be associated with degradation of the DNA double-helix structure [39,40]. Electronic spectra of the complex in the absence and presence of ct-DNA are given in figure 2.…”

“…While groove binding and electrostatic interaction of small molecules with DNA show little or no perturbations on the basestacking and helicity bands, classical intercalative ligands tend to enhance the intensities of bands due to strong base-stacking interactions and stable DNA conformations[40]. The CD spectra of DNA in the presence of the complex are illustrated infigure 4and exhibit a decrease in both the positive and negative bands.…”