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 (S/H) ratio 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 was obtained using the free PGA under the identical reaction conditions. The immobilized PGA can be separated magnetically and recycled for five times without obvious loss of its catalytic activity.