An efficient synthesis of ampicillin on magnetically separable immobilized penicillin G acylase

Penicillin G acylase (PGA ) was immobilized on the magnetic hydrophilic polymer microspheres with average pore size of 17.1 nm, specific surface area of 128.2 m2/g and saturate magnetization of 6.4 emu/g. The 96.7% ampicillin yield with 1.60 of the synthesis/hydrolysis ratio (S/H) from 6-aminopenicillanic acid (6-APA) and D-(-)-alpha-phenylglycine methyl ester (D-PGME) can be achieved using the resultant magnetic biocatalyst in ethylene glycol, where only 82.1% yield with 1.40 of the S/H ratio were obtained by using the free PGA under the identical reaction conditions. The immobilized PGA can be separated magnetically and recycled for 5 times without obvious loss of its catalytic activity.