title: Modification of a styryl dye binding mode with calf thymus DNA in vesicular medium: from minor groove to intercalative.
abstract: This paper reports an interesting transformation of binding mode of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide (DASPMI) with calf thymus DNA from minor groove binding in buffer solution to intercalative binding when the dye is encapsulated inside a vesicle formed by the interaction of 1,8-naphthalimide (a charge transfer dye) with the supramolecular association of sodium dodecyl sulfate and block-copolymer polyethylene-b-polyethylene glycol. The pre-encapsulated dye in the vesicular interior binds intercalatively to ct-DNA, as evinced by the high value of equilibrium binding constant of DASPMI-DNA complex, changes in CD-spectra of DNA and isosbestic point, along with downshift and hypochromicity of absorption band. Increase in anisotropy decay by 1.5 times with a single component strongly confirms restricted motion of the probe inside ct-DNA confirming intercalative binding. The compaction of ct-DNA caused by the interaction of the vesicle allows DASPMI to bind ct-DNA in the intercalative mode. However, the groove binding mode in ct-DNA-DASPMI remains unaffected by the retro-addition of the vesicles to the already bound dye to ct-DNA.
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, India.
authors.forename: Anamika
authors.initials: A
authors.lastname: Manna
authors.forename: Sankar
authors.initials: S
authors.lastname: Chakravorti
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry*; D007364:Intercalating Agents / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011726:Pyridinium Compounds / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D007364:Intercalating Agents; D011726:Pyridinium Compounds; C011786:2-(4-(dimethylamino)styryl)-1-methylpyridinium; D011092:Polyethylene Glycols; D004247:DNA; C427203:calf thymus DNA