Explore the interaction mechanism between artificial synthetic food colorants and digestive proteases via multi-spectral technology and computer simulation.

This study systematically investigated the interaction mechanism between three synthetic food colorants (allura red, tartrazine, and brilliant blue) and trypsin and pepsin using various spectroscopic techniques and computer simulation methods. The results show that all three food colorants form 1:1 complex through moderate strength non-covalent interactions (mainly hydrophobic forces and hydrogen bonds). Tartrazine has a stronger binding affinity with trypsin, while allura red-pepsin system has a stronger binding affinity. The binding ability of tartrazine with trypsin is greater than that with pepsin, while the other two food colorants is just the opposite. All colorants cause partial unfolding of the trypsin/pepsin peptide chains, a decrease in the content of α-helix, β-turns, and random coils, and an increase in the content of β-sheets. Computer simulation results indicate that all three food colorants bind near the catalytic active pocket of trypsin, especially allura red. The binding region of tartrazine covers the catalytic core and substrate binding pocket of pepsin. During the simulation time, the complex formed by tartrazine with trypsin/pepsin is the most unstable. Tartrazine reduces the solvent accessible surface area (SASA) of trypsin and decreases the structural compactness of pepsin. All other systems lead to an increase in structural compactness and an increase in SASA. These findings suggest that the potential health risks of allura red and tartrazine may deserve more attention, especially tartrazine. This study provides key insights for food safety assessment and formula optimization, highlighting the need to develop more scientific food safety standards for the use of synthetic colorants.