Toxic Interaction Mechanism of food Colorant Sunset Yellow with trypsin by Spectroscopic and Computational Method

Abstract

The interaction between food colorant sunset yellow (SY) and trypsin (TRP) was studied by multiple spectroscopic and molecular docking methods and molecular docking simulation under simulated physiological conditions to evaluate the toxic of SY at the protein level. The results showed that SY could effectively quench the endogenous fluorescence of TRP, formed a 1:1 complex. The binding distance (r) between SY and TRP was obtained based on the Förster nonradioactive resonance energy transfer and r was less than 7 nm, which indicated that there was a non-radiative energy transition in the system. The thermodynamic parameters were obtained from the van't Hoff equation, and the Gibbs free energy ΔG<0, indicating that the reaction was spontaneous; ΔH<0, ΔS>0, indicating hydrophobic interaction played a major role in forming the SY-TRP complex. Molecular docking results showed that SY was surrounded by the active amino acid residues Ser195, His57 and Asp102 of TRP, which altered the microenvironment of amino acid residues at the catalytic active center of TRP. Furthermore, as shown by the synchronous fluorescence, UV-Visible absorption and circular dichroism data, SY could lead to the conformational and microenvironmental changes of TRP, which may affect its physiological function.