title: Two subtle amino Acid changes in a transaminase substantially enhance or invert enantiopreference in cascade syntheses.
abstract: 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.
authors: Biotechnology and Enzyme Catalysis, Institute of Biochemistry, Felix-Hausdorff-Strasse 4, 17487 Greifswald (Germany).
authors: Lilly
authors: L
authors: Skalden
authors: Christin
authors: C
authors: Peters
authors: Jonathan
authors: J
authors: Dickerhoff
authors: Alberto
authors: A
authors: Nobili
authors: Henk-Jan
authors: HJ
authors: Joosten
authors: Klaus
authors: K
authors: Weisz
authors: Matthias
authors: M
authors: Höhne
authors: Uwe T
authors: UT
authors: Bornscheuer
mesh_terms: D000588:Amines / Q000378:metabolism; D019943:Amino Acid Substitution; D008958:Models, Molecular; D011487:Protein Conformation; D013237:Stereoisomerism; D013379:Substrate Specificity; D000637:Transaminases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014733:Vibrio / Q000201:enzymology
chemical_list: D000588:Amines; D000637:Transaminases
keywords: amine transaminases; cascade synthesis; enantiopreference; enzyme catalysis; protein engineering