Supramolecular effect of curcurbit[7]uril on the binding mode of 2-(4-(dimethylamino) styryl)-1-methylpyridinium iodide with Calf Thymus DNA: From minor groove to intercalative

• Free DASPMI binds with DNA in groove binding mode.
• Binding mode of DASPMI with DNA changes while parked inside CB[7].
• DASPMI inside CB[7] binds with DNA in intercalative mode.
• Molecular docking nicely corroborate the intercalative binding.
• Morphological change of DASPMI·CB[7]–DNA complex with CB[7].

The effect of curcurbit[7]uril (CB[7]) in the binding mode of 2-(4-(dimethylamino) styryl)-1-methylpyridinium (DASPMI) with Calf Thymus DNA has been discussed in this paper. Red shift, intensity change in absorption and emission spectra and presence of isosbestic point with increasing concentration of CB[7] in groove bound DASPMI–DNA complex indicates a change in binding pattern. Appearance of a third slower component in lifetime decay in presence of CB[7] which gets more slow in high CB[7] concentration is indicative of a new type of binding. Major changes in ct-DNA bands in circular dichroism spectra with addition of CB[7] make a strong case for intercalative binding. Increased computed values of binding constant associated with diminishing quenching constant in presence of potassium iodide make a positive candidate for intercalative binding. Formation of big spherical condensate in DASPMI–DNA complex in presence of CB[7] which grows bigger in higher CB[7] concentration shows a morphological change. Molecular docking nicely portrays the intercalative nature of binding corroborating the experimental evidences.

The binding mode of 2-(4-(dimethylamino) styryl)-1-methylpyridinium (DASPMI) with Calf Thymus DNA in aqueous solution changes from groove to intercalative when complexed with cucurbit[7]uril.Figure optionsDownload as PowerPoint slide