The hydrophilic epoxy polymer GHM magnetic beads

copolymerizing glycidyl methacrylate (GMA) - 2-hydroxyethyl methacrylate (HEMA) - N

N′-methylene bisacrylamide (MBAA) in the presence of magnetic Fe3O4 powder

were prepared by designing a novel inverse suspension polymerization system

and were used as the support for immobilization of penicillin G acylase (PGA).The magnetic Fe3O4 in GHM beads had inversed cubic spinel structure and paramagnetic characteristics.A number of epoxy groups

hydrophilic hydroxyl and amido groups exist on the surface of the GHM beads and provide a micro-environment suitable for the immobilization of PGA

and the enzyme molecules can be immobilized covalently on the surface of GHM beads by the reaction between the amido groups of PGA and the active epoxy groups of the support.The GHM beads possessed a large pore size (mainly ranging from 15 nm to 55 nm) and a large specific surface area so that the immobilized enzyme (PGA/GHM) had high enzyme loading.As a result

the apparent activity of PGA/GHM reached 748 IU·g-1 for hydrolyzing penicillin G potassium into 6-aminopenicillanic acid at 37oC

and its activity had not changed obviously after 15 recycles.The PGA loaded beads can settle quickly in the magnetic field and be separated easily from the product in applications.