Immobilization of lipase and penicillin acylase on hydrophobic acrylic carriers

Abstract

This paper describes the immobilization of lipase and penicillin acylase (PA) on hydrophobic acrylic carriers crosslinked with ethylene glycol dimethacrylate (EGDMA) and diethylene glycol dimethacrylate (DEGDA). Two methods of immobilization were used for lipase—physical adsorption on unmodified copolymers and covalent attachment on carriers with amino groups, whereas penicillin acylase was only covalently linked to carriers with amino groups. Physical adsorption gave preparations with high activity and specific activity but poor storage stability. In the best case the immobilized lipase had specific activity 36,352 U/L/mg, that is two times higher than the native enzyme used in an immobilization procedure. However, physically immobilized lipase retained only 20–35% of the initial activity after 3-month storage. Covalent attachment gave less active but stable preparations. Highly hydrophobic carrier composed of 2-ethylhexyl acrylate (2EHA)/EGDMA and modified with 1,4 diaminobutane gave the best results in covalent immobilization of lipase since enzyme retained relatively high activity (10,587 U/L/mg) and storage stability (62.5% of initial value). The best carriers for penicillin acylase immobilization are crosslinked with DEGDA as they display preferential sorption and then immobilization of penicillin acylase, what leads to highly active preparations. The best carrier – BA/DEGDA modified with 1,4-diaminobutane – immobilized 5.46 mg of protein/mL with specific activity 1.59 U/mg. More than 70% of this initial activity was retained after 1-month storage of this enzymatic preparation.