Continuous production of 3‐fluoro‐L‐alanine with alanine dehydrogenase

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Abstract
Alanine dehydrogenase catalyzed the conversion of 3‐fluoropyruvate into 3‐fluoro‐L‐alanine in the presence of NADH and ammonia. The optimum pH of the reaction was 7.8. The Km values of the enzyme for 3‐fluoropyruvate, polyethylene glycol‐bound NADH, and ammonia were 2.94, 0.56, and 105mM, respectively. 3‐Fluoro‐L‐alanine was selectively and continuously produced from 3‐fluoropyruvate and ammonium formate in an enzyme membrane reactor by the multienzyme reaction system of alanine dehydrogenase and formate dehydrogenase with a simultaneous coenzyme regeneration. The average conversion and the space–time yield were 73% and 75 g/L day, respectively, with operation of the reactor for 4 days. Alanine dehydrogenase and formate dehydrogenase consumed were 11, 370 and 22, 950 units/kg 3‐fluoro‐L‐alanine, respectively. The cycle number was 3150 mol/mol NAD.