(536c) Biocatalysis of Beta-Lactam Antibiotics

The directed evolution of enzymes such as Penicillin G Acylase (PGA) for greater synthetic utility will be reported here. PGA is an industrially important enzyme used in the hydrolysis of penicillin G to 6-aminopenicillanic acid (6-APA) and phenyl acetic acid. In turn, 6-APA is used in the synthesis of other b-lactam antibiotics such as amoxicillin and ampicillin. The engineering of PGA is challenging as it is an 86kDa hetero-dimeric protein and it has a complex maturation process which includes production of a precursor which is eventually exported in the periplasm for processing. The signal sequence from alpha-subunit is removed and the alpha-beta linker region is also removed via intra-molecular proteolysis. We applied semi-rational design on PGA for improved functional properties and will report on our findings. An enhanced PGA would be advantageous for improved green processes for semi-synthetic synthesis of conventional and novel antibiotics. Potentially useful enzymes for antibiotics synthesis will also be discussed.