title: Binding and Inhibitory Effect of the Dyes Amaranth and Tartrazine on Amyloid Fibrillation in Lysozyme.
abstract: Interaction of two food colorant dyes, amaranth and tartrazine, with lysozyme was studied employing multiple biophysical techniques. The dyes exhibited hypochromic changes in the presence of lysozyme. The intrinsic fluorescence of lysozyme was quenched by both dyes; amaranth was a more efficient quencher than tartrazine. The equilibrium constant of amaranth was higher than that of tartarzine. From FRET analysis, the binding distances for amaranth and tartrazine were calculated to be 4.51 and 3.93 nm, respectively. The binding was found to be dominated by non-polyelectrolytic forces. Both dyes induced alterations in the microenvironment surrounding the tryptophan and tyrosine residues of the protein, with the alterations being comparatively higher for the tryptophans than the tyrosines. The interaction caused significant loss in the helicity of lysozyme, the change being higher with amaranth. The binding of both dyes was exothermic. The binding of amaranth was enthalpy driven, while that of tartrazine was predominantly entropy driven. Amaranth delayed lysozyme fibrillation at 25 μM, while tartrazine had no effect even at 100 μM. Nevertheless, both dyes had a significant inhibitory effect on fibrillogenesis. The present study explores the potential antiamyloidogenic property of these azo dyes used as food colorants.
authors.affiliation: Biophysical Chemistry Laboratory Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology , Kolkata 700 032, India.
authors.forename: Anirban
authors.initials: A
authors.lastname: Basu
authors.affiliation: Biophysical Chemistry Laboratory Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology , Kolkata 700 032, India.
authors.forename: Gopinatha
authors.identifier: 0000-0002-3596-979X
authors.initials: G
authors.lastname: Suresh Kumar
mesh_terms: D000548:Amaranth Dye / Q000737:chemistry / Q000494:pharmacology*; D000682:Amyloid / Q000037:antagonists & inhibitors* / Q000378:metabolism; D001665:Binding Sites / Q000187:drug effects; D004396:Coloring Agents / Q000737:chemistry / Q000494:pharmacology*; D031541:Fluorescence Resonance Energy Transfer; D005505:Food Coloring Agents / Q000737:chemistry / Q000494:pharmacology*; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D013645:Tartrazine / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000682:Amyloid; D004396:Coloring Agents; D005505:Food Coloring Agents; D000548:Amaranth Dye; D009113:Muramidase; D013645:Tartrazine