How the presence of a small molecule affects the complex coacervation between lactoferrin and β-lactoglobulin

Heteroprotein complex coacervation corresponds to the formation of two liquid phases in equilibriuminduced by the interaction of two oppositely charged proteins. The more concentrated phase known ascoacervate phase, has attracted interest from several fields of science due to its potential applicationsfor example for encapsulation and delivery of bioactives. Prior such application, it is necessary to under-stand how the presence of small ligands affects the complex coacervation. In this work, we report onthe interaction of small ligand with individual proteins -lactoglobulin ( -LG) and lactoferrin (LF) andconsequences on their complex coacervation. ANS (8-Anilinonaphthalene-1-sulfonic acid), a fluorescentprobe, was used as model ligand. While ANS did not interact with -LG, it presented two sets of bindingsites with LF inducing its self-aggregation. Depending on its concentration, ANS modulated the shapeof -LG-LF macromolecular assembly. Coacervates were observed for ANS/LF molar ratio