Efficient enzymatic synthesis of ampicillin in organic media

The kinetically controlled synthesis of ampicillin with immobilized penicillin acylase (IPA) from Escherichia coli in fully organic medium was studied. d-phenylglycine methyl ester (d-PGM) was selected as the activated acyl donor due to its good solubility in organic solvents. A series of organic solvents with different polarity were screened and ethyl acetate was found to be the most satisfying solvent for the enzymatic synthesis of ampicillin. Remarkable catalytic activity of the IPA was retained in ethyl acetate, and high yield could be obtained. Furthermore, some significant factors that greatly affect the ampicillin synthesis process, such as substrate concentration, temperature and water content of IPA etc., were investigated in details. As a result, high yield (92.9%) and synthesis/hydrolysis (S/H) ratio (1.50) were successfully achieved under the optimum conditions.