Exploring the interactions between bovine serum albumin and sodium propionate through multi-spectroscopic and molecular docking analyses

To investigate the influence of sodium propionate (SP) on bovine serum albumin (BSA), it is important to study its thermodynamic properties, binding mode, and its impact on the conformation of it. Herein, the interactions between BSA and SP were examined using various spectroscopic methods and molecular docking analyses. The Stern-Volmer plot revealed that the SP can efficiently quench the BSA intensity through a mechanism of hybrid quenching. Fluorescence quenching of BSA emission intensity in existence of SP implies that the microenvironment around the fluorophores (Trp residues) is altered. The calculated thermodynamic parameters suggests that the SP interacts with BSA through hydrogen bonds and van der Waals interactions. According to the results, the most significant change in synchronous fluorescence of BSA occurred in the vicinity of the Trp microenvironment residues rather than the Tyr residues. The results of site-competitive replacement studies determined that SP can be bound to site I and II in the BSA molecule. FT-IR spectroscopy results showed that the secondary structure of the BSA undergoes changes after interacting with SP. Using molecular docking analysis, the binding energy of SP toward BSA was-6.26 kJ mol-1, indicating a favorable binding affinity to the protein.