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pH-insensitive electrostatic interaction of carmoisine with two serum proteins: A possible caution on its uses in food and pharmaceutical industry

Paper ID Volume ID Publish Year Pages File Format Full-Text
30360 44472 2013 13 PDF Available
Title
pH-insensitive electrostatic interaction of carmoisine with two serum proteins: A possible caution on its uses in food and pharmaceutical industry
Abstract

•Current study focuses on electrostatic interaction of carmoisine with HSA and BSA.•Primarily electrostatic interaction, binding strength is independent of pH.•Dye–protein interaction is significantly reduced with increasing ionic strength.•The work is important in protein mediated purification of similar dyes.•Possibility of health hazards arising out of use of such food colorants.

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.

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Keywords
Carmoisine; Serum proteins; Fluorescence quenching; Specific binding; Thermodynamic parameters
First Page Preview
pH-insensitive electrostatic interaction of carmoisine with two serum proteins: A possible caution on its uses in food and pharmaceutical industry
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 124, 5 July 2013, Pages 50–62
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering