Stereoselective synthesis of (R)-(+)-1-(1-naphthyl)ethylamine by ω-amine transaminase immobilized on amino modified multi-walled carbon nanotubes and biocatalyst recycling

Immobilized enzymes exhibit favorable advantages in biocatalysis, such as high operation stability, feasible reusability, and improved organic solvents tolerance. Herein, an immobilized ω-amine transaminase AtATA@MWCNTs-NH₂ is successfully prepared using amino modified multi-walled carbon nanotubes as carrier and glutaraldehyde as crosslinker. Under the optimum immobilization conditions, the activity recovery is 78.7%. Compared with purified enzyme AtATA, AtATA@MWCNTs-NH₂ possesses superior stability, even in harsh conditions (e.g., high temperature, acidic or alkali environment, and different kind of organic solvents). To simplify the separation and extraction of products, we choose methanol (10%, v/v) as the cosolvent, replacing DMSO (20%, v/v) in our previous work, for the catalytic reaction of AtATA@MWCNTs-NH₂. AtATA@MWCNTs-NH₂ can be used for stereoselective synthesis (R)-(+)- 1(1-naphthyl)ethylamine ((R)-NEA) for 15 cycles, with the e.e._p (enantiomeric excess) > 99.5%. The catalytic process of AtATA@MWCNTs-NH₂ achieves cycle production of (R)-NEA using methanol as cosolvent.