Engineered, Scalable Production of Optically Pure l-Phenylalanines Using Phenylalanine Ammonia-Lyase from .

An efficient preparative-scale synthetic procedure of l-phenylalanine derivatives has been developed using mutant variants of phenylalanine ammonia-lyase from (PAL). After rigorous reaction engineering, the PAL-catalyzed hydroamination reaction of cinnamic acids provided several unnatural amino acids of high synthetic value, such as ()-- and ()--methoxyphenylalanine; ()-- and ()--methylphenylalanine; and ()-- and ()--bromophenylalanine at preparative scale, significantly surpassing the catalytic efficiency in terms of conversions and yields of the previously reported PAL-based biotransformations. The PAL variants tolerated high substrate and product concentrations, representing an important extension of the PAL-toolbox, while the engineered biocatalytic procedures of improved E-factor and space-time yields fulfill the requirements of sustainable and green chemistry, providing facile access to valuable amino acid building blocks.