β-Aryl-β-amino acid aminotransferase from Variovorax sp. JH2 is useful for enantioselective β-phenylalanine production

A bacterium, Variovorax sp. JH2, has an ability to degrade (S)-β-phenylalanine stereoselectively. The enzyme involved in the degradation, (S)-β-phenylalanine:2-oxoglutarate aminotransferase, was purified to homogeneity from Variovorax sp. JH2 and characterized. The enzyme was useful for (R)-β-phenylalanine production from racemic β-phenylalanine by enantioselective decomposition of (S)-β-phenylalanine through transamination. (S)-β-Phenylalanine and (S)-3-amino-3-(3-pyridyl)propionate served as good amino-donors in the transamination and 2-oxoglutarate, oxaloacetate, pyruvate, and 1,3-acetonedicarboxylate served as amino-acceptors. The enzyme had a molecular weight of about 72,000 and consisted of two identical subunits. Three internal amino acid sequences (54, 67, and 63 residues) were determined and showed homology with glutamate-1-semialdehyde 2,1-aminomutases.