Comparison of the omega-transaminases from different microorganisms and application to production of chiral amines.
Microorganisms that are capable of (S)-enantioselective transamination of chiral amines were isolated from soil samples by selective enrichment using (S)-alpha-methyl-benzylamine ((S)-alpha-MBA) as a sole nitrogen source. Among them, Klebsiella pneumoniae JS2F, Bacillus thuringiensis JS64, and Vibrio fluvialis JS17 showed good omega-transaminase (omega-TA) activities and the properties of the omega-TAs were investigated. The induction level of the enzyme was strongly dependent on the nitrogen source for the strains, except for V. fluvialis JS17. All the omega-TAs showed high enantioselectivity (E>50) toward (S)-alpha-MBA and broad amino donor specificities for arylic and aliphatic chiral amines. Besides pyruvate, aldehydes such as propionaldehyde and butyraldehyde showed good amino acceptor reactivities. All the omega-TAs showed substrate inhibition by (S)-alpha-MBA above 200 mm. Moreover, substrate inhibition by pyruvate above 10 mm was observed for omega-TA from V. fluvialis JS17. In the case of product inhibition, acetophenone showed much greater inhibitions than L-alanine for all omega-TAs. Comparison of the enzyme properties indicates that omega-transaminase from V. fluvialis JS17 is the best one for both kinetic resolution and asymmetric synthesis to produce enantiomerically pure chiral amines. Kinetic resolution of sec-butylamine (20 mM) was done under reduced pressure (150 Torr) to selectively remove an inhibitory product (2-butanone) using the enzyme from V. fluvialis JS17. Enantiomeric excess of (R)-sec-butylamine reached 94.7% after 12 h of reaction.
Shin
J S
JS
School of Chemical Engineering and Institute for Molecular Biology and Genetics, Seoul National University, Korea. enzymo@kist.re.kr
Kim
B G
BG
D000588:Amines / Q000138:chemical synthesis*; D001413:Bacillus thuringiensis / Q000201:enzymology; D002082:Butylamines / Q000737:chemistry; D003956:Dialysis; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000201:enzymology; D008968:Molecular Conformation; D012988:Soil Microbiology; D013237:Stereoisomerism; D013379:Substrate Specificity; D000637:Transaminases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D014733:Vibrio / Q000201:enzymology; D051278:beta-Alanine-Pyruvate Transaminase
D000588:Amines; D002082:Butylamines; D004791:Enzyme Inhibitors; D000637:Transaminases; D051278:beta-Alanine-Pyruvate Transaminase