Spectroscopy analysis and molecular docking of toxic interaction mechanism of tartrazine with Pepsin
Hongcai Zhang, Baosheng Liu, Xu Cheng
The interaction between tartrazine (TTZ) and pepsin (PEP) was studied by various spectroscopy and molecular docking simulation techniques under the experimental conditions of pH=2.20. The results showed that TTZ could effectively quench the endogenous fluorescence of PEP, formed a 1:1 complex. 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 TTZ-PEP complex. Molecular docking results showed that TTZ was bound in the hydrophobic cavity of PEP and surrounded by active amino acid residues Asp32 and Asp215, which changed the microenvironment of amino acid residues at the catalytic active center of PEP. Furthermore, as shown by the synchronous fluorescence, UV-Vis absorption and circular dichroism data, TTZ could lead to the conformational changes of PEP, which might affect its physiological function.