Optical spectroscopic exploration of binding of cochineal red a with two homologous serum albumins

Priyanka Bolel, Niharendu Mahapatra, Mintu Halder

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


Cochineal Red A is a negatively charged synthetic azo food colorant and a potential carcinogen. We present here the study of binding of Cochineal Red A with two homologous serum albumins, human (HSA) and bovine (BSA), in aqueous pH 7.4 buffer by optical spectroscopic techniques. Protein intrinsic fluorescence quenching by Cochineal Red A occurs through ground-state static interaction and its binding with BSA is stronger than with HSA. The magnitudes of thermodynamic parameters suggest that dye binding occurs principally via electrostatic complexation. Site-marker competitive binding shows that Cochineal Red A binds primarily to site I of serum albumins. Circular dichroic spectra indicate that dye binding results in some conformational modification of serum albumins. Increased ionic strength of the medium results in lowering of binding. This study provides an important insight into possible means of removal of dye toxicity.

Original languageEnglish
Pages (from-to)3727-3734
Number of pages8
JournalJournal of Agricultural and Food Chemistry
Issue number14
StatePublished - 11 Apr 2012
Externally publishedYes


  • dye binding
  • fluorescence quenching
  • serum protein
  • site marker

ASJC Scopus subject areas

  • Chemistry (all)
  • Agricultural and Biological Sciences (all)


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