Studying the interaction mechanism between bovine serum albumin and lutein dipalmitate: Multi-spectroscopic and molecular docking techniques

Bovine serum albumin (BSA) is a natural protein commonly used to prepare nanoparticle to encapsulate food ingredients. The interaction between lutein dipalmitate and BSA was investigated using fluorescence, UV-vis absorption, circular dichroism (CD) spectroscopies and molecular docking. The fluorescence quenching study suggested the quenching process of BSA by lutein dipalmitate was static, which was consistent with the results of UV-vis absorption. The binding parameters proved that the binding stoichiometry between BSA and lutein dipalmitate was 1:1. Molecular docking revealed that lutein dipalmitate bound to site I on BSA, which was confirmed by site competitive experiments. Moreover, thermodynamic study and molecular docking suggested lutein dipalmitate spontaneously bound to BSA by hydrogen bond, van der Waals force, and hydrophobic interaction. The synchronous and three-dimensional fluorescence showed that the microenvironment of Tyr and Trp was changed and the protein skeleton got loosened in the presence of lutein dipalmitate. According to CD, a decrease in alpha-helix content of BSA was observed upon the addition of lutein dipalmitate.