The interaction between the azo dye tartrazine and α-Chymotrypsin enzyme: Molecular dynamics simulation and multi-spectroscopic investigations

Such azo dyes as tartrazine (Tar) are known as recalcitrant xenobiotic compounds which can cause environmental pollution. These hazardous materials may be exposed to body biomolecules throughout the swallowing process; thus, it is essential to thoroughly investigate the properties of such compounds. Therefore, in this study, multiple chemistry methods including Molecular dynamics (MD) simulation, molecular docking and different spectroscopic techniques were employed to address the possible binding interaction of Tar with the model digestive protease α-Chymotrypsin (α-Chy). Molecular docking analysis exhibited the exact binding location of Tar in the α-Chy structure. MD simulation also confirmed the stability of the α-Chy-Tar system during the simulation time scale. These findings had excellent correlations with the experimental results obtained from spectroscopic studies. The experimental results revealed that Tar could bind to α-Chy and effectively quench its intrinsic fluorescence through the static quenching mechanism. Thermodynamic data also showed that van der Waals interactions and hydrogen bonds had a leading role in stabilizing the α-Chy-Tar complex. Finally, circular dichroism results showed a change in the secondary structural components of α-Chy during the binding of Tar. This study, thus, provides insights into the binding interaction of Tar with α-Chy.