(188af) Exploring and Enhancing the Activity and Substrate Specificity of Amine Dehydrogenases

Exploring and
enhancing the activity and substrate specificity of Amine Dehydrogenases

Robert D. Franklin‡, Conner M.
Mount#, Bettina R. Bommarius‡, Andreas S. Bommarius‡#

‡School of Chemical and
Biomolecular Engineering, Georgia Institute of Technology,

Parker H. Petit Institute for Bioengineering and Bioscience,

Engineered Biosystems Building, 950 Atlantic Drive N.W., GA 30322, USA

#School of Chemistry and
Biochemistry, Georgia Institute of Technology,

950 Atlantic Drive, Atlanta, GA 30332-2000, USA

Amine dehydrogenases (AmDHs) are a
family of engineered enzymes which catalyze the reductive amination of ketones
to chiral amines, an important class of compounds for the
production of active pharmaceutical ingredient.^1-3 AmDHs take
ammonia, ketone, and NADH as substrates and release an (R)-amine, NAD⁺,
and water as products as seen in the reaction scheme below. When our group
first reported AmDHs in 2012 and until very recently, the substrate scope was
relatively unexplored. Most of the work in the field has focused on the F-AmDH
and its activity on aromatic ketones. In the present work, we report on our
efforts to improve the leucine amine dehydrogenase-derived L-AmDH. Through
site-directed mutagenesis guided by molecular docking simulations, we have
introduced mutations at key residues which increase activity towards long
aliphatic ketones by more than 1000-fold. We also report other variants which
have increased activity across the board without affecting substrate
specificity. Finally, we have demonstrated for the first-time activity toward
ketones with polar substituents, rather than just simple alkyl groups. As the
variety of substrates accepted by AmDHs increases, so too does their utility for the production of pharmaceuticals and fine chemicals.

References:

1.            Abrahamson,
M. J.; Vazquez-Figueroa, E.; Woodall, N. B.; Moore, J. C.; Bommarius, A. S.,
Development of an amine dehydrogenase for synthesis of chiral amines. Angew Chem Int
Ed Engl 2012, 51 (16), 3969-72.

2.            Abrahamson,
M. J.; Wong, J. W.; Bommarius, A. S., The Evolution of an Amine Dehydrogenase
Biocatalyst for the Asymmetric Production of Chiral Amines. Advanced Synthesis
& Catalysis 2013, 355 (9), 1780-1786.

3.            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.