Development of the reversible PGA immobilization by using the immobilized metal ion affinity membrane

In this study, an immobilized metal ion affinity membrane (IMAM) was prepared and used to immobilize penicillin G acylase (PGA). The stability of storage of the immobilized PGA membrane (IPM) was tested. When stored in deionized water (DI) at 4 °C, only 19% residual activity of IPM was retained for 10 days. However, when stored in 10 mM phosphate buffer (PB, pH 8) with 0.1% NaN3, the IPM can retain 99% of its activity for a 10-day reaction and storage test. The feasibility of the IPM regeneration after a long period of reaction was investigated. When using 100 mM EDTA as the stripping solution, the re-immobilized capacity for PGA is only 52% of the original one after 4 regenerations. When the regeneration process was modified by using the stripping solution (300 mM NaCl, 25 mM EDTA, 20 mM PB, pH 8) for 30 min, then immersed in 0.5 M HCl and 0.5 M NaOH respectively for 10 min, the resulting IMAM can reserve 99% PGA immobilized activity after 5 regenerations.