Investigation on the interaction of food colorant Sudan III with bovine serum albumin using spectroscopic and molecular docking methods.

ABSTRACT

Sudan III is a coloring agent used in chemical industries and food additives. This article uses spectroscopic and molecular docking methods to investigate the interaction of Sudan III with bovine serum albumin (BSA) under a physiological condition. Spectroscopic analysis of the emission quenching revealed that the quenching mechanism of BSA by Sudan III was static. The binding sites and constants of Sudan III-BSA complex were observed to be from 0.72 and 6.41 × 102 L·mol-1 to 0.69 and 5.83 × 102 L·mol-1 at 298 and 310 K, respectively. The enthalpy change (ΔH) and entropy change (ΔS) revealed that van der Waals forces and hydrogen bonds stabilized the Sudan III-BSA complex. Energy transfer from tryptophan to Sudan III occurred by a fluorescence resonance energy transfer mechanism, and the r distance (3.32 nm) had been determined. The results of UV-Vis absorption, synchronous, three-dimensional fluorescence, and circular dichroism spectra showed that Sudan III induced conformational changes of BSA. Molecular docking studies revealed that Sudan III situated within subdomain IIA of BSA. A study on the interaction between Sudan III and BSA was of fundamental importance for providing more information about the potential toxicological effect of chemicals at the molecular level.