Patent ID: 8329877

Claim:
A method for partitioning or separating proteins or polypeptides linked to choline binding polypeptides characterized by: a) contacting i) a crude or partially purified extract of a cell culture, or the extracellular medium of a cell culture, or a mixture of different chemical compounds containing at least one protein or polypeptide whose sequence has at least one choline-binding structural motif, ii) with a mixture of water, polyethylenglicol (PEG) and salts or other polymers more than 5% soluble in water, the resulting mixture being spontaneously structured into a binary system with two aqueous phases, A and B, phase A being richer in PEG than phase B, and wherein proteins or polypeptides with said choline-binding motifs partition preferentially to phase A b) optionally suppressing the preferential partitioning of said proteins or polypeptides containing the choline binding motifs to phase A, by adding a solution containing choline.