Patent ID: 7439336

Claim:
A process for purifying interleukin-18 binding protein (IL-18BP) from a fluid comprising at least one step using aqueous two-phase partitioning that comprises a polyethylene glycol (PEG) phase and a (Na 2 )SO 4 salt phase, wherein the concentrations of PEG and (Na) 2 SO 4 in the two phases are calculated according to the following formula: y=− 2.5108 x+ 35.159 a) wherein y=PEG in % [w/w] and x=(Na 2 )SO 4 in % [w/w]; y=− 2.5573 x+ 35.757 b) wherein y=PEG in % [w/w] and x=(Na 2 )SO 4 in % [w/w]; or y=− 2.1182 x+ 35.355 c) wherein y =PEG in % [w/w] and x=(Na 2 )SO 4 in % [w/w].