Production of Phenylpyruvic Acid by Engineered L-Amino Acid Deaminase from Proteus Mirabilis

Objectives This study aimed to develop an efficient enzymatic strategy for the industrial production of phenylpyruvate (PPA) from L-phenylpyruvic acid (L-Phe). Results L-amino acid deaminase from Proteus mirabilis (L-pmAAD) was expressed in E. coli BL21(DE3) and modified to release product inhibition by employing conformational dynamics engineering. Based on structural analysis, two residues (E145A/L341A) were identified for reducing interactions between the product and enzyme and increasing flexibility of the protein, thereby facilitating the product release. The mutant M2E145A/E341A exhibited a 3.84-fold reduction in product inhibition and a 1.35-fold increase in catalytic efficiency in comparison to the wild type. Finally, 81.2 g/L PPA production with a conversion of 99.6% was obtained in a 5-L bioreactor. Conclusion The engineered catalyst can significantly reduce product inhibition and facilitate the effective industrial synthesis of PPA.