title: Spectroscopic and microcalorimetric studies on the molecular binding of food colorant acid red 27 with deoxyribonucleic acid.
abstract: Interaction of the food colorant acid red 27 with double stranded DNA was investigated using spectroscopic and calorimetric methods. Absorbance and fluorescence studies suggested an intimate binding interaction between the dye and DNA. The quantum efficiency value testified an effective energy transfer from the DNA base pairs to the dye molecules. Minor groove displacement assay with Hoechst 33258 revealed that the binding occurs in the minor groove of DNA. Circular dichroism studies revealed that acid red 27 induces moderate conformational perturbations in DNA. Results of calorimetric studies suggested that the complexation process was driven largely by positive entropic contribution with a smaller favorable enthalpy contribution. The equilibrium constant of the binding was calculated to be (3.04 ± 0.09) × 10(4)  M(-1) at 298.15 K. Negative heat capacity value along with the enthalpy-entropy compensation phenomenon established the involvement of dominant hydrophobic forces in the binding process. Differential scanning calorimetry studies presented evidence for an increased thermal stability of DNA on binding of acid red 27. Copyright © 2016 John Wiley & Sons, Ltd.
authors: Biophysical Chemistry Laboratory, Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, Kolkata, 700 032, India.
authors: Anirban
authors: A
authors: Basu
authors: Biophysical Chemistry Laboratory, Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, Kolkata, 700 032, India.
authors: Gopinatha Suresh
authors: GS
authors: Kumar
mesh_terms: D000548:Amaranth Dye / Q000737:chemistry / Q000494:pharmacology*; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D005505:Food Coloring Agents / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D005505:Food Coloring Agents; D004247:DNA; D000548:Amaranth Dye
keywords: DNA; acid red 27; minor groove binding; thermodynamics