Engineered phenylalanine dehydrogenase in organic solvents: homogeneous and biphasic enzymatic reactions

The use of engineered phenylalanine dehydrogenase N145A supported on Celite for the reductive amination of phenylpyruvic acid in homogeneous and biphasic aqueous-organic solvents is reported. The results indicate that the immobilised biocatalyst is remarkably robust, even in the presence of high concentrations of polar or non-polar organic solvents such as acetone, methanol, n-hexane, toluene and methylene chloride. Cofactor regeneration with alcohol dehydrogenase from Saccharomyces cerevisiae and ethanol was successfully explored. Application to the non-natural poorly water-soluble 2-oxo acid p-NO2-phenylpyruvic acid was successfully performed, resulting in the biocatalytic synthesis of p-NO2-phenylalanine. In all cases 100% stereoselectivity for the production of the amino acid was retained.