Separate Sets of Mutations Enhance Activity and Substrate Scope of Amine Dehydrogenase
Robert D. Franklin, Conner J. Mount, Bettina Bommarius, Andreas S. Bommarius
Abstract
Abstract Mutations were introduced into the leucine amine dehydrogenase (L‐AmDH) derived from G. stearothermophilus leucine dehydrogenase (LeuDH) with the goals of increased activity and expanded substrate acceptance. A triple variant (L‐AmDH‐TV) including D32A, F101S, and C290V showed an average of 2.5‐fold higher activity toward aliphatic ketones and an 8.0 °C increase in melting temperature. L‐AmDH‐TV did not show significant changes in relative activity for different substrates. In contrast, L39A, L39G, A112G, and T133G in varied combinations added to L‐AmDH‐TV changed the shape of the substrate binding pocket. L‐AmDH‐TV was not active on ketones larger than 2‐hexanone. L39A and L39G enabled activity for straight‐chain ketones as large as 2‐decanone and in combination with A112G enabled activity toward longer branched ketones including 5‐methyl‐2‐octanone.