Investigation of Aqueous Two-phase Partitioning System for Model Proteins Separation

摘要

Aqueous two-phase extraction (ATPE) is a liquid–liquid extraction technique which employs two aqueous phases comprising two polymers or a polymer and a salt or other two phases. ATPE is not only an environmentally benign technique due to no organic solvents used, but also a protein-friendly process. In this paper, partition behavior of model proteins (BSA, lysozyme, trypsin, pepsin) was investigated with different phase composition. The effect of phase forming salt concentration, (NH4)2SO4 and Na2HPO4 as salt and ATPE pH on protein partitioning were discussed. The purpose is to find protein partitioning rules in two aqueous phases and to guide two phases selection. Results show that with salt concentration in ATPE system increases from 12% to 20%, BSA partition coefficient increases, but lysozyme decreases. Different kinds of salts also affect the separation. (NH4)2SO4 caused more proteins partition in up phase than sodium phosphate did. pH changes the surface charge of proteins and changes their partition.