A biocatalytic route to enantiomerically pure unsaturated α-H-α-amino acids

A set of both enantiomeric forms of nonproteinogenic, unsaturated alpha -H-alpha -amino acids was efficiently synthesized using a biocatalytic pathway. This route involved the straightforward synthesis of the required unsaturated amino acid amides, followed by resolution with an aminopeptidase present in Pseudomonas putida ATCC 12633 and/or a genetically modified organism, leading to the (S)-acids and (R)-amides. Undesired amino acid racemase activity was identified in the wild-type strain, which was absent in the newly developed organism. The (R)-amides were hydrolyzed under mild conditions using an amidase present in whole cells from Rhodococcus erythropolis NCIMB 11540 to the (R)-acids. The viability of this procedure was demonstrated with the in multi-grain synthesis of a variety of unsaturated amino acids in excellent enantiopurity.