LAUSR

Finding faster and simpler ways to screen protein sequence space to enable the identification of new biocatalysts for asymmetric synthesis remains both a challenge and a rate-limiting step in enzyme discovery. Biocatalytic strategies for the synthesis of chiral amines are increasingly attractive and include enzymatic asymmetric reductive amination, which offers an efficient route to many of these high-value compounds. Here we report the discovery of over 300 new imine reductases and the production of a large (384 enzymes) and sequence-diverse panel of imine reductases available for screening. We also report the development of a facile high-throughput screen to interrogate their activity. Through this approach we identified imine reductase biocatalysts capable of accepting structurally demanding ketones and amines, which include the preparative synthesis of N-substituted β-amino ester derivatives via a dynamic kinetic resolution process, with excellent yields and stereochemical purities. High-throughput biocatalytic screening and metagenomics have been used to discover over 300 imine reductases (IREDs) and subsequently produce a sequence-diverse panel of IREDs suitable for optimizing the synthesis of chiral amines. Additional characterization identified biocatalysts that accommodate structurally demanding amines and ketones for enzymatic reductive aminations.