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.