Aqueous Two-Phase Extraction of Enzymes

ATPS consist of two hydrophilic components, termed phase formers, (most likely either polymer – polymer or polymer – salt) dissolved in water above a critical concentration, forming two immiscible liquid phases. State of the Art in developing/identifying ATPS for the purification of biomolecules is based on trial and error screening methods, which are cost- and time-consuming. Therefore, a thermodynamic based modeling approach for the determination of tailor-made ATPS for different biomolecules is required to enable a target-oriented purification. Phase equilibria data, either determined experimentally or modeled applying the ePC-SAFT equation of state [3], is used to determine an initial choice of applicable ATPS based on the molecular interactions of the phase forming components and water. In order to take the interactions of the biomolecules in the ATPS into account, and thus gain access to aggregation propensity and partitioning behavior of the biomolecules, the osmotic virial coefficients B22 (biomolecule - biomolecule interactions) and B23 (biomolecule - solute interactions) are used. Osmotic virial coefficients lower than zero indicate attractive interactions, values higher than zero indicate repulsive interactions.

Using this information a tailor-made ATPS for the purification of industrial relevant biomolecules, optimized towards solubility of the biomolecule simultaneously maximizing the extraction yield, can be obtained.