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Molecules 2018, 23(5), 1211;

β-Phenylalanine Ester Synthesis from Stable β-Keto Ester Substrate Using Engineered ω-Transaminases

Institute of Process Engineering in Life Sciences, Section II: Technical Biology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
Department of Biotechnology & Enzyme Catalysis, University of Greifswald, Institute of Biochemistry, Felix-Hausdorff-Str. 4, 17487 Greifswald, Germany
These authors contributed equally to this work.
Author to whom correspondence should be addressed.
Academic Editor: Frank Hollmann
Received: 16 April 2018 / Revised: 12 May 2018 / Accepted: 15 May 2018 / Published: 18 May 2018
(This article belongs to the Special Issue Frontier in Biocatalysis for Organic Synthesis)
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The successful synthesis of chiral amines from ketones using ω-transaminases has been shown in many cases in the last two decades. In contrast, the amination of β-keto acids is a special and relatively new challenge, as they decompose easily in aqueous solution. To avoid this, transamination of the more stable β-keto esters would be an interesting alternative. For this reason, ω-transaminases were tested in this study, which enabled the transamination of the β-keto ester substrate ethyl benzoylacetate. Therefore, a ω-transaminase library was screened using a coloring o-xylylenediamine assay. The ω-transaminase mutants 3FCR_4M and ATA117 11Rd show great potential for further engineering experiments aiming at the synthesis of chiral (S)- and (R)-β-phenylalanine esters. This alternative approach resulted in the conversion of 32% and 13% for the (S)- and (R)-enantiomer, respectively. Furthermore, the (S)-β-phenylalanine ethyl ester was isolated by performing a semi-preparative synthesis. View Full-Text
Keywords: β-phenylalanine ethyl ester; β-amino acid; ω-transaminase; asymmetric synthesis β-phenylalanine ethyl ester; β-amino acid; ω-transaminase; asymmetric synthesis

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Buß, O.; Voss, M.; Delavault, A.; Gorenflo, P.; Syldatk, C.; Bornscheuer, U.; Rudat, J. β-Phenylalanine Ester Synthesis from Stable β-Keto Ester Substrate Using Engineered ω-Transaminases. Molecules 2018, 23, 1211.

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