Engineered Aminotransferase for the Production of d ‐Phenylalanine Derivatives Using Biocatalytic Cascades

Abstract d‐Phenylalanine derivatives are valuable chiral building blocks for a wide range of pharmaceuticals. Here, we developed stereoinversion and deracemization biocatalytic cascades to synthesize d‐phenylalanine derivatives that contain electron‐donating or ‐withdrawing substituents of various sizes and at different positions on the phenyl ring with a high enantiomeric excess (90 to >99 % ee) from commercially available racemic mixtures or l‐amino acids. These whole‐cell systems couple Proteus mirabilis l‐amino acid deaminase with an engineered aminotransferase that displays native‐like activity towards d‐phenylalanine, which we generated from Bacillus sp. YM‐1 d‐amino acid aminotransferase. Our cascades are applicable to preparative‐scale synthesis and do not require cofactor‐regeneration systems or chemical reducing agents.