Kynureninase in Organic Synthesis: Preparation of γ-Hydroxy-α-l-Amino Acids

Kynureninase, which is known to catalyze the transaldol reaction between benzaldehyde and kynurenine, accepted many kinds of other aromatic aldehydes and propargyl aldehydes as the substrates to afford novel γ-hydroxy-α-l-amino acids. The l-configuration of the α-carbons was confirmed by an enzymatic method using both d- and l-amino acid oxidases. The stereochemistry of the newly formed chiral center (γ-position) in major isomers was determined to be R-configuration by the observed NOEs in the NMR spectroscopy of lactones derived from the γ-hydroxy-α-l-amino acids.

kynureninase - aromatic aldehyde - propargylaldehyde - γ-(R)-hydroxy-α-l-amino acids - KDO