Kinetic Resolution of Racemic Amines to Enantiopure (<i>S</i>)-amines by a Biocatalytic Cascade Employing Amine Dehydrogenase and Alanine Dehydrogenase

oleh: Mahesh D. Patil, Sanghan Yoon, Hyunwoo Jeon, Taresh P. Khobragade, Sharad Sarak, Amol D. Pagar, Yumi Won, Hyungdon Yun

Format: Article
Diterbitkan: MDPI AG 2019-07-01

Deskripsi

Amine dehydrogenases (AmDHs) efficiently catalyze the NAD(P)H-dependent asymmetric reductive amination of prochiral carbonyl substrates with high enantioselectivity. AmDH-catalyzed oxidative deamination can also be used for the kinetic resolution of racemic amines to obtain enantiopure amines. In the present study, kinetic resolution was carried out using a coupled-enzyme cascade consisting of AmDH and alanine dehydrogenase (AlaDH). AlaDH efficiently catalyzed the conversion of pyruvate to alanine, thus recycling the nicotinamide cofactors and driving the reaction forward. The <i>ee</i> values obtained for the kinetic resolution of 25 and 50 mM <i>rac</i>-&#945;-methylbenzylamine using the purified enzymatic systems were only 54 and 43%, respectively. The use of whole-cells apparently reduced the substrate/product inhibition, and the use of only 30 and 40 mg<sub>DCW</sub>/mL of whole-cells co-expressing AmDH and AlaDH efficiently resolved 100 mM of <i>rac</i>-2-aminoheptane and <i>rac</i>-&#945;-methylbenzylamine into the corresponding enantiopure (<i>S</i>)-amines. Furthermore, the applicability of the reaction protocol demonstrated herein was also successfully tested for the efficient kinetic resolution of wide range of racemic amines.