title: Interaction of phenazinium dyes with double-stranded poly(A): spectroscopy and isothermal titration calorimetry studies.
abstract: A comprehensive study on the binding of phenazinium dyes viz. janus green B, indoine blue, safranine O and phenosafranine with double stranded poly(A) using various spectroscopic and calorimetric techniques is presented. A higher binding of janus green B and indoine blue over safranine O and phenosafranine to poly(A) was observed from all experiments. Intercalative mode of binding of the dyes was inferred from fluorescence polarization anisotropy, iodide quenching and viscosity experiments. Circular dichroism study revealed significant perturbation of the secondary structure of poly(A) on binding of these dyes. Results from isothermal titration calorimetry experiments suggested that the binding was predominantly entropy driven with a minor contribution of enthalpy to the standard molar Gibbs energy. The results presented here may open new opportunities in the application of these dyes as RNA targeted therapeutic agents.
authors.affiliation: Biophysical Chemistry Laboratory, Chemistry Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India.
authors.forename: Asma Yasmeen
authors.initials: AY
authors.lastname: Khan
authors.affiliation: Biophysical Chemistry Laboratory, Chemistry Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India.
authors.forename: Baishakhi
authors.initials: B
authors.lastname: Saha
authors.affiliation: Biophysical Chemistry Laboratory, Chemistry Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India. Electronic address: gskumar@iicb.res.in.
authors.forename: Gopinatha Suresh
authors.initials: GS
authors.lastname: Kumar
mesh_terms: D001665:Binding Sites; D002151:Calorimetry; D002942:Circular Dichroism; D004396:Coloring Agents / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D010619:Phenazines / Q000737:chemistry / Q000378:metabolism*; D011061:Poly A / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013816:Thermodynamics; D017186:Titrimetry
chemical_list: D004396:Coloring Agents; D010619:Phenazines; D011061:Poly A
keywords: Calorimetry; Intercalation; Phenazinium dyes; Poly(A); Spectroscopy