Selective coacervation between lactoferrin and the two isoforms of β-lactoglobulin

• Lactoferrin and β-lactoglobulin interact and form coacervates.
• Lactoferrin interact selectively with the two isoforms A & B of β-lactoglobulin.
• A minimum β-lactoglobulin/Lactoferrin molar ratio of 4 is required for coacervation.

This work reports on the impact of subtle change of protein charge on coacervation and subsequent liquid–liquid phase separation between two oppositely charged globular proteins. For this purpose, a comparative study was conducted on the coacervation of lactoferrin (LF) with the two β-lactoglobulin (β-LG) isoforms. Upon mixing LF with an excess of β-LG, microspheres were formed throughout coacervation under narrow pH range (5.4–6.0). At the optimal pH of coacervation, LF being the limiting partner under tested concentration ranges. The β-LG/LF molar ratio recovered in the formed coacervates varied from 4 to 8 depending on the total protein concentration. Remarkably, LF showed a selective coacervation with isoform A of β-LG as judged by a larger concentration domain for coacervation and a high yield of LF recovered once mixed with β-LG A i.e. 80% against a maximum of 42% with β-LG B. At thermodynamic level, the interaction of LF with both β-LG isoforms exhibited complex exothermic binding isotherms with both enthalpic and entropic contributions.

Figure optionsDownload as PowerPoint slide