Aqueous two-phase affinity partitioning of penicillin acylase from E. coli in presence of PEG-derivatives

The partitioning of penicillin acylase from E. coli in PEG–salt aqueous two-phase system in the presence of modified PEGs, i.e. PEG-benzoate (PEG-Bz), PEG-phosphate (PEG-PO4), PEG-trimethylamine (PEG-tma), PEG-palmitate (PEG-pal), and PEG-phenylacetamide (PEG-paa) has been studied. For each PEG-derivative, the phase diagram was constructed and selective extraction of the enzyme was investigated. Since, in the case of PEG-Bz and PEG-paa, the activity of the enzyme decreased in the PEG-rich phase, the possibility of the specific group binding to the active site of the enzyme was investigated by molecular simulation.