Albumin binding study to sodium lactate food additive using spectroscopic and molecular docking approaches

Abstract

Sodium lactate (SL) is a lactic acid salt that is used in the food and pharmaceutical industries due to its antioxidant and antibacterial properties. Therefore, for the first time we investigated the interaction of SL with the bovine serum albumin (BSA) using spectroscopic and molecular modeling studies under physiological conditions. Fluorescence studies were performed at three different temperatures and the attained results showed emission intensity decrease upon addition of SL. Calculated thermodynamic parameters demonstrated that van der Waals interactions and hydrogen bonds were the main forces in the binding of SL to BSA. The negative sign of standard Gibbs free energy (∆G°) showed that the BSA-SL complex formation was a spontaneous molecular interaction process. The results of UV–Vis spectroscopy showed a ground-state complex formation between BSA and SL and confirmed the results of fluorescence quenching study which showed the quenching mechanism was static. Results of molecular docking indicated a stable binding for lactate to BSA on Sudlow II and lowest calculated binding energy for the interaction was −7.87 kcal/mol. Also, the significant role of two amino acid residues (Lys 499, Lys 533) in the binding process of BSA with SL was approved. This investigation provides important insight into the mechanism of sodium lactate interaction with BSA in vitro.