SELECTIVE RECOVERY OF PROTEINS BY CONTROL OF THEIR SURFACE-PROPERTIESUTILIZING PEG-BOUND AFFINITY LIGANDS

Selective recovery of proteins by control of their surface properties is investigated by using a ligand modified aqueous two-phase system (A TPS) and polyethylene glycol (PEG) precipitation. The ligands used wer e nonionic surfactant (Triton and PEG-palmitate) and PEG-bound dye (Ci bacron Blue and Procion Yellow). Both the partition coefficient in ATP S and the solubility in a PEG solution of Bovine Serum Albumin (BSA) i ncrease significantly with the addition of these ligands, because the surface net hydrophobicity of BSA is increased by the binding of these hydrophobic ligands. On the other hand, these ligands have no effect on the partition behavior and solubility of Carbonic Anhydrase (CAB) a nd Ovalbumin (OvA), which have no binding sites to the ligands. Contro l of the surface properties of protein by these specific bindings of l igands can be utilized to improve the separation efficiency in ATPS an d PEG precipitation. A separation process using ligand modified ATPS a nd PEG precipitation is developed.