Asymmetric synthesis of an unnatural amino acid was demonstrated by ω-transaminase from Vibrio fluvialis JS17. L-2-Aminobutyric acid was synthesized from 2-oxobutyric acid and benzylamine with an enantiomeric excess higher than 99%. The reaction showed severe product inhibition by benzaldehyde, which was overcome by employing a biphasic reaction system to remove the inhibitory product from the aqueous phase. In a typical biphasic reaction (50 mM 2-oxobutyric acid, 70 mM benzylamine and 2.64 U/ml purified enzyme) using hexane as an extractant, conversion of 2-oxobutyric acid reached 96% in 5 h whereas only 39% conversion was obtained without the product extraction.
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Acknowledgment This work was supported by BK21 program from the Korean Ministry of Education, start-up research funds provided by Yonsei University and Seoul R&BD Program (NT080612, KU080657).
All Science Journal Classification (ASJC) codes
- Applied Microbiology and Biotechnology