A polyacrylic acid as a carrier for immobilization of penicillin acylase

A copolymer of acrylic acid with divinylbenzene was synthesized by suspension polymerization. This polymer is an effective carrier. Penicillin acylase was immobilized on this carrier to convert benzylpenicillin to 6-aminopenicillanic acid, which may be employed in the manufacture of semisynthetic penicillins. Factors that affect the activity of immobilized penicillin acrylase, such as temperature, pH, and amount of native enzyme, were studied. Under suitable conditions, the activity and activity recovery of the immobilized enzyme were 3100 U/g (dry carrier, p-dimethylaminobenzaldehyde method) and 59.7%, respectively. The immobilized penicillin acylase shows a remarkable increase in stability. At 40°C and pH 8.0 the value of the kinetic Michaelis-Menten constant (Km) of the immobilized enzyme is 2.8 × 10-3 mol/L, and the value of activation energy of enzyme catalysis is 71.5 kJ/mol.