title: pH-insensitive electrostatic interaction of carmoisine with two serum proteins: a possible caution on its uses in food and pharmaceutical industry.
abstract: Here we have investigated the binding of carmoisine, a water-soluble azo food colorant, with serum proteins (HSA and BSA) by fluorescence and UV-VIS spectroscopy, circular dichroism and molecular docking studies. Results indicate that fluorescence quenching of protein has been due to site-specific binding of the dye with biomacromolecules. Site marker competitive binding and molecular docking explorations show that interaction occurs in the sub-domain ІІA of HSA and the sub-domains ІІA and ІB in the case of BSA. Conformational investigation indicates that dye binding modifies the secondary structure of proteins and this also alters the microenvironment of the tryptophan(s). The interaction is found to be pH-insensitive which can have relevance to the toxicological profiles of the dye, and ionic strength dependence of binding can be exploited in protein purification mediated by such food colorants.
authors: Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721 302, India.
authors: Shubhashis
authors: S
authors: Datta
authors: Niharendu
authors: N
authors: Mahapatra
authors: Mintu
authors: M
authors: Halder
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002626:Chemistry, Pharmaceutical; D002942:Circular Dichroism; D005505:Food Coloring Agents / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D009282:Naphthalenesulfonates / Q000737:chemistry* / Q000378:metabolism; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism; D055672:Static Electricity
chemical_list: D005505:Food Coloring Agents; D009282:Naphthalenesulfonates; D012709:Serum Albumin; C006671:azo rubin S