Study on the partition of beta-galactosidase from Escherichia coli in aqueous two-phase systems and elaboration of a simple procedure for the purification of the enzyme to homogeneity.

The partition of beta-galactosidase from Escherichia coli in aqueous two-phase systems composed of poly(ethylene glycol)/Aquaphase PPT or poly(ethylene glycol)/potassium phosphate, respectively, has been studied thoroughly by varying diverse parameters of the phase forming conditions. The enzyme was found to partition in both systems predominantly to the upper poly(ethylene glycol) containing phase, while the protein bulk of E. coli is concentrated in the lower phase. Optimum conditions for the employment of the two-phase partition for the purification of the enzyme were elaborated leading to a simple and effective procedure in which the enzyme was isolated to homogeneity with 70% recovery.