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Modification of a styryl dye binding mode with calf thymus DNA in vesicular medium: from minor groove to intercalative.

Authors
  • Manna, Anamika
  • Chakravorti, Sankar
Type
Published Article
Journal
The Journal of Physical Chemistry B
Publisher
American Chemical Society
Publication Date
May 03, 2012
Volume
116
Issue
17
Pages
5226–5233
Identifiers
DOI: 10.1021/jp301211m
PMID: 22506549
Source
Medline
License
Unknown

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.

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