AMINOTRANSFERASE-CATALYZED CONVERSION OF D-AMINO ACIDS TO L-AMINO-ACIDS

A microbial bioconversion process is described for the conversion of D-amino acids or the corresponding racemic mixtures to L-amino acids. The process comprises reacting a D-amino acid or a D,L mixture of an amino acid with glucose and ammonia in the presence of an aminotransferase-containing culture of Escherichia coli. The aminotransferase is only moderately stereoselective in converting D- and L-amino acids to the keto acids. The aminotransferase-mediated conversion of alpha-keto acid to L-amino acid exhibits very high stereospecificity, thus rendering the conversion of D-amino acids irreversible. Conversions of leucine, phenylalanine, and homophenylalanine to the corresponding L isomers are described.