Ampicillin Synthesis Using a Two-Enzyme Cascade with Both α-Amino Ester Hydrolase and Penicillin G Acylase

The current enzymatic production of semisynthetic beta-lactam antibiotics requires isolation and purification of the intermediate 6-aminopenicillanic acid which adds cost and complexity to the manufacturing process. In this work, we took advantage of the unique substrate specificity of a-amino ester hydrolases to perform a purely aqueous one-pot production of ampicillin from penicillin G and D-phenylglycine methyl ester, catalyzed by a-amino ester hydrolase and penicillin G acylase. The synthesis was performed in both a one-pot, one-step synthesis resulting in a maximum conversion of 39%, and a one-pot, two-step process resulting in a maximum conversion of 47%. The two-enzyme cascade reported in this paper is a promising alternative to the current enzymatic two-step, two-pot manufacturing process for semisynthetic beta-lactam antibiotics which requires intermittent isolation of 6-aminopenicillanic acid.