Reductive amination: Methods for cell-free and whole-cell biocatalysis.

Enzymatic reductive amination is now a green and selective method for the efficient conversion of ketones into chiral amines with high optical purity. Transaminases (TAs) have been widely employed at both laboratory and industrial scale for the synthesis of primary amines. Additionally, amine dehydrogenases (AmDHs), imine reductases (IREDs) and reductive aminases (RedAms) enable the stereoselective synthesis of primary, secondary and tertiary amines. Recent advancements in protein engineering have expanded the substrate scope and improved the stability of these biocatalysts, enabling broader applications. The use of immobilized enzymes and whole-cell systems further enhances the efficiency and sustainability of these methods. This chapter provides detailed protocols for enzymatic reductive amination for the synthesis of primary, secondary, and tertiary chiral amines using isolated or immobilized enzymes, or whole-cell biocatalysts.