Protein-selective coacervation with hyaluronic acid

Area of Science:

• Biochemistry
• Materials Science
• Separation Science

Background:

• Protein purification is crucial in biotechnology.
• Existing methods can be inefficient for proteins with similar properties.
• Developing selective separation techniques is essential.

Purpose of the Study:

• To investigate selective coacervation for protein separation.
• To isolate bovine serum albumin (BSA) from β-lactoglobulin (BLG) using hyaluronic acid (HA).
• To understand the mechanisms governing protein-polyelectrolyte interactions.

Main Methods:

• Selective coacervation using hyaluronic acid (HA).
• Determination of pH transitions (complex formation, coacervation, precipitation, redissolution) as a function of ionic strength.
• Isothermal titration calorimetry (ITC) to assess binding affinity.
• Confocal laser microscopy for visualizing coacervation dynamics.

Main Results:

• Achieved 90% purity of BSA from a 1:1 mixture with BLG using HA.
• BSA exhibited higher HA affinity due to its concentrated positive domain.
• pH transition values provided insights into protein charge and interaction mechanisms.
• Confocal microscopy showed droplet coalescence into a film.
• Reversal of selectivity observed with polycation poly(diallyldimethylammonium chloride) (PDADMAC).

Conclusions:

• Selective coacervation with HA is an effective method for protein purification.
• Protein charge distribution significantly influences polyelectrolyte binding affinity.
• The choice of polyelectrolyte charge dictates separation selectivity.
• Further research can optimize coacervation for specific protein separations.