Kinetic studies of bovine serum albumin interaction with PG and TBHQ using surface plasmon resonance

Propyl gallate (PG) and tert-butylhydroquinone (TBHQ) are examples of phenolic antioxidant agents, which have widespread uses in food industry. In this study, for the first time, we report on the interaction of PG and TBHQ with bovine serum albumin (BSA) using surface plasmon resonance (SPR). In order to modify Au slide with carboxyl functional group, 11-mercaptoundecanoic acid (MUA) was used. After activation of carboxylic groups, BSA was immobilized onto the MUA through both covalent amide bond and electrostatic binding formation. The SPR analysis showed dose-response sensograms of BSA upon increasing concentration of PG and TBHQ. At pH 4.5, the equilibrium dissociation constant or affinity unit (K_D) for PG and TBHQ were 1.89e⁻¹⁰ and 1.49e⁻¹⁰ and at pH 7.5 were 4.74e⁻¹⁰ and 1.83e⁻⁹, respectively. The smaller amount of K_D demonstrated high food additive molecules affinity to BSA. Based on these findings, it can be concluded that PG and TBHQ molecules can interact with BSA and effectively distributed within the body. Besides, SPR can be considered as useful automatic tool for quantification of PG and TBHQ interaction with serum albumin and it can deliver precise real-time kinetic data.