Design of Aqueous Two-Phase Extraction System for Protein Separation

Purification of high-value proteins calls for a method that provides mild environment for proteins, highly selective while giving high yield, can be integrated with upstream processes, can handle high throughput, and most importantly, costs less comparatively to other conventional technique. Aqueous Two-Phase Extraction System (ATPES) offers all these advantages, however its realization at industrial scales is rather limited. Among hindering factors is the limited design approaches capable of accurate prediction of system and product behaviour that offer large scope of application with operation assessment and performance sensitivity available for ATPES. This paper describes the framework designed to calculate the amount of phase-forming components needed to extract a target protein from a complex mixture of cell lysate via either one or two stages of ATPES. The thermodynamics of phase formation and partitioning are modeled using Flory-Huggins theory and calculated based on a non-linear minimization of Gibbs energy difference approach. As a case study, the design of suitable flowsheets for the extraction of a model feedstock containing phosphofructokinase using water-PEG6000-DxT500 and water-PEG6000-Na3PO4 systems is developed. The flowsheets are compared based on protein's yield and purity, settling rate and cost factor.