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

An efficient preparative-scale synthetic procedure of l -phenylalanine derivatives has been developed using mutant variants of phenylalanine ammonia-lyase from Arabidopsis thaliana ( At PAL). After rigorous reaction engineering, the At PAL-catalyzed hydroamination reaction of cinnamic acids provided several unnatural amino acids of high synthetic value, such as ( S )- m - and ( S )- p -methoxyphenylalanine; ( S )- o - and ( S )- m -methylphenylalanine; and ( S )- o - and ( S )- p -bromophenylalanine at preparative scale, significantly surpassing the catalytic efficiency in terms of conversions and yields of the previously reported Pc PAL-based biotransformations. The At 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.