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

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 K m values of the enzyme for 3‐fluoropyruvate, polyethylene glycol‐bound NADH, and ammonia were 2.94, 0.56, and 105m M , 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.