Exploration of the Substrate Diversity of the Amine Transaminase 3FCR‐4M and its Engineered Variants

ABSTRACT

Enantioselective transamination of prochiral ketones is an indispensable transformation in the pharmaceutical and fine chemical industries. Transaminases have emerged as valuable biocatalysts for the preparation of a wide range of chiral amines through either kinetic resolution or asymmetric synthesis. Here, we explored the synthetic potential of the engineered amine transaminase 3FCR‐4M through systematic evaluation of combinatorial variants in both kinetic resolution and asymmetric synthesis mode. This dual assessment not only revealed synergistic effects between individually beneficial mutations, but also offered insight into the limited predictive value of kinetic resolution activity for asymmetric synthesis efficiency. Notably, we report for the first time the transaminase‐catalyzed direct amination of a terminal alkyne‐bearing substrate. The transamination of 1‐(4‐ethynylphenyl)ethanone proceeded with >99% conversion and excellent enantioselectivity (>99%ee), opening a new perspective for the integration of transaminase catalysis into click chemistry‐based synthetic workflows.