Kinetic resolution of chiral amines with omega-transaminase using an enzyme-membrane reactor

A kinetic resolution process for the production of chiral amines was develo ped using an enzyme-membrane reactor (EMR) and a hollow-fiber membrane cont actor with (S)-specific omega -transaminases (omega -TA) from Vibrio fluvia lis JS17 and Bacillus thuringiensis JS64. The substrate solution containing racemic amine and pyruvate was recirculated through the EMR and inhibitory ketone product was selectively extracted by the membrane contactor until e nantiomeric excess of (R)-amine exceeded 95%. Using the reactor set-up with fiat membrane reactor (10-mL working volume), kinetic resolutions of alpha -methylbenzylamine (alpha -MBA) and 1-aminotetralin (200 mM, 50 mL) were c arried out. During the operation, concentration of ketone product, i.e., ac etophenone or alpha -tetralone, in a substrate reservoir was maintained bel ow 0.1 mM, suggesting efficient removal of the inhibitory ketone by the mem brane contactor. After 47 and 32.5 h of operation using 5 U/mL of enzyme, 9 8.0 and 95.5% ee of (R)-alpha -MBA and (R)-1-aminotetralin were obtained at 49.5 and 48.8% of conversion, respectively. A hollow-fiber membrane reacto r (39-mL working volume) was used for a preparative-scale kinetic resolutio n of 1-aminotetralin (200 mM, 1 L). After 133 h of operation, enantiomeric excess reached 95.6% and 14.3 g of (R)-1-aminotetralin was recovered (97.4% of yield). Mathematical modeling of the EMR process including the membrane contactor was performed to evaluate the effect of residence time. The simu lation results suggest that residence time should be short to maintain the concentration of the ketone product in EMR sufficiently low so as to decrea se conversion per cycle and, in turn, reduce the inhibition of the omega -T A activity. (C) 2001 John Wiley & Sons, Inc.