Characterizing the noncovalent binding behavior of tartrazine to lysozyme: A combined spectroscopic and computational analysis.

Tartrazine is a stable water-soluble azo dye widely used as a food additive, which could pose potential threats to humans and the environment. In this paper, we evaluated the response mechanism between tartrazine and lysozyme under simulated conditions by means of biophysical methods, including multiple spectroscopic techniques, isothermal titration calorimetry (ITC), and molecular docking studies. From the multispectroscopic analysis, we found that tartrazine could effectively quench the intrinsic fluorescence of lysozyme to form a complex and lead to the conformational and microenvironmental changes of the enzyme. The ITC measurements suggested that the electrostatic forces played a major role in the binding of tartrazine to lysozyme with two binding sites. Finally, the molecular docking indicated that tartrazine had specific interactions with the residues of Trp108. The study provides an important insight within the binding mechanism of tartrazine to lysozyme in vitro.