Binding thermodynamic, spectroscopic and molecular docking study of Allura Red AC to Bovine Serum Albumin

Abstract

The goal of this study is to investigate the interaction between sulfonated azo dye, disodium 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-2-naphthalenesulfonate, known as Allura Red ACand bovine serum albumin (BSA) using UV-vis absorption spectroscopy‚ fluorescence quenching method and molecular docking studies. The physicochemical properties of Allura Red ACwere also studied in 5 mM aqueous phosphate buffer of pH 7.0 at 25° C. The results show no aggregate formation of Allura Red AC by increasing of Allura Red AC concentration and ionic strength. The binding constant of Allura Red ACwith BSA was calculated to be 3.1×10⁴ M^-1 at 298 K. The results of thermodynamic parameters for binding modes at different temperatures showed that the hydrophobic interaction play a major role for the binding of Allura Red ACto BSA. The results of fluorescence studies showed that Allura Red AC quenched the fluorescence emission of BSA by static mechanism and the binding constant (K_b) and the binding point (n) were obtained to be 1.2758 and 0.413 at 298 K, respectively. This work could help us to go further in understanding the binding mechanism of azo dyes that are used as food colorant with the carrier protein in blood plasma.