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Metal‐Ion‐Mediated Tuning of Duplex DNA Binding by Bis(2‐(2‐pyridyl)‐1 H ‐benzimidazole)
Author(s) -
Bhattacharya Santanu,
Chaudhuri Padmaparna
Publication year - 2007
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200700014
Subject(s) - ethylenediaminetetraacetic acid , benzimidazole , chelation , chemistry , metal ions in aqueous solution , ligand (biochemistry) , dna , divalent , metal , circular dichroism , stereochemistry , crystallography , inorganic chemistry , organic chemistry , biochemistry , receptor
Studies of double‐stranded‐DNA binding have been performed with three isomeric bis(2‐( n ‐pyridyl)‐1 H ‐benzimidazole)s ( n =2, 3, 4). Like the well‐known Hoechst 33258, which is a bisbenzimidazole compound, these three isomers bind to the minor groove of duplex DNA. DNA binding by the three isomers was investigated in the presence of the divalent metal ions Mg 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ . Ligand–DNA interactions were probed with fluorescence and circular dichroism spectroscopy. These studies revealed that the binding of the 2‐pyridyl derivative to DNA is dramatically reduced in the presence of Co 2+ , Ni 2+ , and Cu 2+ ions and is abolished completely at a ligand/metal‐cation ratio of 1:1. Control experiments done with the isomeric 3‐ and 4‐pyridyl derivatives showed that their binding to DNA is unaffected by the aforementioned transition‐metal ions. The ability of 2‐(2‐pyridyl)benzimidazole to chelate metal ions and the conformational changes of the ligand associated with ion chelation probably led to such unusual binding results for the ortho isomer. The addition of ethylenediaminetetraacetic acid (EDTA) reversed the effects completely.