(316e) Towards Scalable Production of Enantiomerically Pure Amines: Enzyme Mechanism and Kinetics

Towards
scalable production of enantiomerically pure amines: enzyme mechanism and
kinetics

Robert D. Franklin‡, John M. Robbins‡, Joshua A.
Whitley‡, 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) catalyze the reductive amination
of prochiral ketones to produce chiral amine compounds^1-3. The reaction requires ammonia as
the nitrogen source and a hydride transfer from an NADH cofactor, as seen in
the reaction scheme below. Chiral amines are frequent intermediates in high
value active pharmaceutical ingredients. AmDHs were developed by engineering
the substrate binding pocket of amino acid dehydrogenases (AADHs) to eliminate
activity towards keto acids and introduce activity toward ketones. Determining
kinetics is a necessary step toward to designing a reactor for processing on
scale.  While significant work has been done to determine the kinetics of
AADHs, the same treatment has not been given to AmDHs. In the present work, we
demonstrate the first detailed study into the kinetic mechanism of amine
dehydrogenases, in both the reductive amination and oxidative deamination
directions. Of particular interest are the differences and similarities between
the mechanisms and kinetics of AmDHs and their parent AADHs, as well as the
inhibition patterns. We also employed isothermal titration calorimetry to
determine binding order and relative substrate affinity. Lastly, we
investigated temperature- and pH-dependence of the rate. Understanding of
enzyme kinetics, and determination of a rate law are key steps toward
developing a viable API manufacturing strategy using enzyme catalysts.

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.            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.

3.            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.