Partitioning of B-galactosidase from Lactobacillus delbrueckii ssp. bulgaricus in Polyethylene Glycol/ Potassium Phosphate Aqueous Two-Phase Systems

Abstract

The partitioning behaviour of B-galactosidase from Lactobacillus delbrueckii ssp bulgaricus was investigated in aqueous two-phase systems (ATPS) composed of polyethylene glycol and potassium phosphate buffer. Different molecular weights of PEG (3350 and 8000) with various concentrations of potassium dihydrogen phosphate (KH2PO4) at pH 6.5 were employed. The enzyme preferably partitioned to the phosphate rich phase when high concentrations of KH2PO4 were used. Moreover, an increase in NaCl concentrations induced the enzyme favoured in the bottom phase. At near neutral pH some part of the enzyme moved to the top phase but after changing the pH values above this point, most of the enzyme preferred to be in the bottom phase.