(438c) Continuous Enzymatic Production of Enantiopure Amines in a Packed Bed Reactor with an Amine Dehydrogenase

Scalable manufacturing of chiral amines is of major importance in the pharmaceutical industry. Biocatalytic production of these compounds offers key advantages including high enantioselectivity, mild operating conditions, and sustainable catalyst production and disposal. However, enzyme stability and retention pose challenges which must be addressed prior to scale-up, a task frequently accomplished by enzyme immobilization. The authors present a continuous flow packed bed reaction platform with co-immobilized amine dehydrogenase¹ (AmDH) and formate dehydrogenase (FDH) on a commercial immobilized metal affinity chromatography resin. AmDHs convert prochiral ketones into chiral amines with the incorporation of ammonia and hydride transfer from NADH. FDH consumes formate to regenerate NADH from NAD⁺, and generates carbon dioxide in the process. Key reactor parameters including residence time, enzyme loading, and reaction temperature were explored to determine their effects on space time yield and total turnover number. The authors report the first stable implementation of AmDH and FDH in a continuous flow reactor, with an apparent half-life exceeding six days.² Productivity values in the reactor ranged between 150 g/L/day and 400 g/L/day, depending on the inlet flow rate. The results underscore the importance of the trade-offs between conversion, productivity, and stability and the engineering decisions in which those trade-offs result. As the biocatalytic production of pharmaceutical ingredients matures, more work must be focused on bridging the gap between protein science and process development.

REFERENCES

1. Bommarius, B. R.; Schurmann, M.; Bommarius, A. S., A novel chimeric amine dehydrogenase shows altered substrate specificity compared to its parent enzymes. Chem Commun (Camb) 2014, 50 (95), 14953-5.
2. Franklin, R. D.; Whitley, J. A.; Caparco, A. A.; Bommarius, B. R.; Champion, J. A.; Bommarius, A., Characterization and optimization of a packed bed reactor with co-immobilized amine dehydrogenase and formate dehydrogenase for the continuous production of chiral amines. Chemical Engineering Journal 2020 (submitted).