Asymmetric synthesis of nonproteinogenic amino acids with l-amino acid transaminase: synthesis of (2S)-2-amino-4-oxo-4-phenylbutyric and (3E,2S)-2-amino-4-phenylbutenoic acids

2,4-Dioxo-4-phenylbutyric acid and 2-oxo-4-phenylbut-3-enoic acid are converted to the corresponding (S)-2-amino acids by recombinant Escherichia coli whole cells over-expressing aromatic transaminase from Enterobacter sp. BK2K-1 (AroATEs) in high yields (68–78%) and high enantiomeric purity (>99%) using l-aspartic acid as an amino donor.

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(3E,2S)-2-Amino-4-phenyl-3-butenoic acidC10H11NO2Ee >99%[α]D25=+38.4 (c 1, 0.1 N HCl)Source of chirality: enzymatic asymmetric transaminationAbsolute configuration: (S)

(2S)-2-Amino-4-oxo-4-phenylbutyric acidC10H11NO3Ee >99%[α]D25=+40.5 (c 0.1, 6 M HCl)Source of chirality: enzymatic asymmetric transaminationAbsolute configuration: (S)