Engineering Transaminase for Stability Enhancement and Site‐Specific Immobilization through Multiple Noncanonical Amino Acids Incorporation

In general, conventional enzyme engineering utilizes 20 canonical amino acids to alter and improve the functional properties of proteins such as stability, and activity. In this study, we utilized the noncanonical amino acid incorporation technique to enhance the functional properties of ω-transaminase (ω-TA). Herein, we enhanced the stability of ω-TA by residue-specific incorporation of (4R)-fluoroproline [(4R)-FP] and successfully immobilized onto chitosan or polystyrene (PS) beads with site-specifically incorporated L-3,4-dihydroxyphenylalanine (DOPA) moiety. The immobilization of ω-TAdopa and ω-TAdp[(4R)-FP] onto PS beads showed excellent reusability for 10 cycles in the kinetic resolution of chiral amines. Compared to the ω-TAdopa, the ω-TAdp[(4R)-FP] immobilized onto PS beads exerted more stability that can serve as suitable biocatalyst for the asymmetric synthesis of chiral amines.