Separation of biopolymers by partition in aqueous two-phase systems

Aqueous two-phase systems are useful tools for fractionation and studies of cell components including proteins and nucleic acids. The systems consist of two non-miscible liquid layers which both have high content of water. The purification achieved by partition of biosubstances between the two liquid phases depends on the possibility to steer the partition in a selective way. The partition can be affected by hydrophobic and affinity ligands, as well as charged groups, bound to soluble polymers.