title: Synthesis, characterization and binding studies of chromium(III) complex containing an intercalating ligand with DNA.
abstract: A chromium(III) complex [Cr(DPPZ)(2)Cl(2)](+), where DPPZ is a planar bidentate ligand with an extended aromatic system, has been found to bind strongly to CT DNA with an apparent binding constant of (1.8+/-0.5)x10(7) M(-1). The effects of [Cr(DPPZ)(2)Cl(2)](+) on the melting temperature and the viscosity of DNA clearly show that the chromium(III) complex interacts with DNA intercalatively. Competitive binding study shows that the enhancement in emission intensity of ethidium bromide (EthBr) in the presence of DNA was quenched by [Cr(DPPZ)(2)Cl(2)](+) indicating that the Cr(III) complex displaces EthBr from its binding site in DNA. The binding of this complex has been found to bring about B to Z conformational transition in CT DNA as well as poly(dG-dC).poly(dG-dC). Molecular modeling study also shows that binding energy of the complex with d(GC)(12) is much higher than Dickerson model and d(AT)(12). Modeling studies show that [Cr(DPPZ)(2)Cl(2)](+) brings about twist in the DNA base pairs as well as phosphate ester backbone resulting in conformational transition in DNA.
authors.affiliation: Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India.
authors.forename: Vaidyanathan Ganesan
authors.initials: VG
authors.lastname: Vaidyanathan
authors.forename: Balachandran Unni
authors.initials: BU
authors.lastname: Nair
mesh_terms: D001667:Binding, Competitive; D002857:Chromium / Q000737:chemistry*; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D007364:Intercalating Agents / Q000737:chemistry*; D008958:Models, Molecular; D009691:Nucleic Acid Denaturation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D013816:Thermodynamics; D014783:Viscosity
chemical_list: D007364:Intercalating Agents; D009942:Organometallic Compounds; D002857:Chromium; D004247:DNA