A study of multi-ligand beta-lactoglobulin complex formation

Beta-lactoglobulin (β-LG), the principal whey protein, possesses multiple sites for binding ligands. Most studies of β-LG-ligand interactions have focused on the formation and dissociation of protein complexes with single ligands, such as α-tocopherol, resveratrol or folic acid. In this study, the possibility of a plurality of bioactive compounds binding simultaneously to β-LG was analysed using protein intrinsic fluorescence quenching. It was found that β-LG could bind two or three ligands simultaneously, although the sequence in which the ligands were added affected binding affinity. The impact of binding to β-LG on physicochemical properties of these three ligands is discussed in view of fluorescence spectroscopy and high performance liquid chromatography results. The data obtained in this study suggest the feasibility of developing β-LG-based carriers of a plurality of active compounds.