Enantioselective N-acetylation of 2-phenylglycine by an unusual N-acetyltransferase from Chryseobacterium sp.

The demand for D-2-phenylglycine used to synthesize semisynthetic antibiotics and pesticides is increasing. We have isolated a Chryseobacterium sp. that selectively transformed the L-form of racemic D,L-2-phenylglycine to (2S)-2-acetylamide-2-phenylacetic acid with a molar yield of 50% and an enantiomer excess of >99.5% under optimal culture conditions, consequently resulting in 99% pure D-2-phenylglycine remaining in the culture. The enantioselective N-acetylation was catalyzed by an acetyl-CoA-dependent N-acetyltransferase whose synthesis was induced by L-2-phenylglycine. The enzyme differed from previously reported bacterial arylamine N-acetyltransferases in molecular mass and substrate specificity. The relative activity ratio of the enzyme with the substrates L-2-phenylglycine, D-2-phenylglycine, 2-(2-chlorophenyl)glycine, and 5-aminosalicylic acid (a good substrate of arylamine N-acetyltransferase) was 100:0:56.9:5.49, respectively. The biotransformation by the N-acetyltransferase-producing bacterium reported here could constitute a new preparative route for the enzymatic resolution of D,L-2-phenylglycine.