Two subtle amino Acid changes in a transaminase substantially enhance or invert enantiopreference in cascade syntheses

Author: Skalden, L.; Peters, C.; Dickerhoff, J.; Nobili, A.; Joosten, H.-J.; Weisz, K.; Hohne, M.; Bornscheuer, U.T.

Description: Amine transaminases (ATAs) are powerful enzymes for the stereospecific production of chiral amines. However, the synthesis of amines incorporating more than one stereocenter is still a challenge. We developed a cascade synthesis to access optically active 3-alkyl-substituted chiral amines by combining two asymmetric synthesis steps catalyzed by an enoate reductase and ATAs. The ATA wild type from Vibrio fluvialis showed only modest enantioselectivity (14 % de) in the amination of (S)-3-methylcyclohexanone, the product of the enoate-reductase-catalyzed reaction step. However, by protein engineering we created two variants with substantially improved diastereoselectivities: variant Leu56Val exhibited a higher R selectivity (66 % de) whereas the Leu56Ile substitution caused a switch in enantiopreference to furnish the S-configured diastereomer (70 % de). Addition of 30 % DMSO further improved the selectivity and facilitated the synthesis of (1R,3S)-1-amino-3-methylcyclohexane with 89 % de at 87 % conversion.

Subject Headings: Amines/metabolism; Amino Acid Substitution; Models, Molecular; Protein Conformation; Stereoisomerism; Substrate Specificity; Transaminases/chemistry/genetics/metabolism; Vibrio/enzymology; amine transaminases; cascade synthesis; enantiopreference; enzyme catalysis; protein engineering

Subject headings:

Publication year: 2015

Journal or book title: Chembiochem : a European Journal of Chemical Biology

Volume: 16

Issue: 7

Pages: 1041-1045

Find the full text :

Find more like this one (cited by):,16&hl=en

Type: Journal Article

Serial number: 2203