Selective separation process of proteins based on the heat stress- induced translocation across phospholipid membranes

Heating of several protein solutions at 40-47°C for 5-60 min in the presence of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes induced the translocation of β-galactosidase (β-gal), α-glucosidase (α- glu) and bovine carbonic anhydrase (CAB) from outer to inner aqueous phase across the liposome membrane. The translocated amounts of β-gal at various temperatures were maximized under suitable heating conditions (45°C, 30 min). Those of α-glu and CAB were maximized at 40-45 and 60°C, respectively. Each maximum value could be correlated with the corresponding local hydrophobicity of each protein evaluated by the aqueous two-phase partitioning method. The possibility to apply these heat-induced translocation phenomena to the bioseparation of proteins was successfully demonstrated for the model mixture solution of β-gal, α-glu and CAB.