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Continuous Flow Bioamination of Ketones in Organic Solvents at Controlled Water Activity using Immobilized ω-Transaminases.

Authors
  • Böhmer, Wesley1
  • Volkov, Alexey2
  • Engelmark Cassimjee, Karim2
  • Mutti, Francesco G1
  • 1 Van't Hoff Institute for Molecular Sciences, HIMS-Biocat University of Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands. , (Netherlands)
  • 2 EnginZyme AB Tomtebodavägen 6 171 65 Solna Sweden. , (Sweden)
Type
Published Article
Journal
Advanced Synthesis & Catalysis
Publisher
Wiley
Publication Date
Apr 27, 2020
Volume
362
Issue
9
Pages
1858–1867
Identifiers
DOI: 10.1002/adsc.201901274
PMID: 32421034
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Compared with biocatalysis in aqueous media, the use of enzymes in neat organic solvents enables increased solubility of hydrophobic substrates and can lead to more favorable thermodynamic equilibria, avoidance of possible hydrolytic side reactions and easier product recovery. ω-Transaminases from Arthrobacter sp. (AsR-ωTA) and Chromobacterium violaceum (Cv-ωTA) were immobilized on controlled porosity glass metal-ion affinity beads (EziG) and applied in neat organic solvents for the amination of 1-phenoxypropan-2-one with 2-propylamine. The reaction system was investigated in terms of type of carrier material, organic solvents and reaction temperature. Optimal conditions were found with more hydrophobic carrier materials and toluene as reaction solvent. The system's water activity (aw) was controlled via salt hydrate pairs during both the biocatalyst immobilization step and the progress of the reaction in different non-polar solvents. Notably, the two immobilized ωTAs displayed different optimal values of aw, namely 0.7 for EziG3-AsR-ωTA and 0.2 for EziG3-Cv-ωTA. In general, high catalytic activity was observed in various organic solvents even when a high substrate concentration (450-550 mM) and only one equivalent of 2-propylamine were applied. Under batch conditions, a chemical turnover (TTN) above 13000 was obtained over four subsequent reaction cycles with the same batch of EziG-immobilized ωTA. Finally, the applicability of the immobilized biocatalyst in neat organic solvents was further demonstrated in a continuous flow packed-bed reactor. The flow reactor showed excellent performance without observable loss of enzymatic catalytic activity over several days of operation. In general, ca. 70% conversion was obtained in 72 hours using a 1.82 mL flow reactor and toluene as flow solvent, thus affording a space-time yield of 1.99 g L-1 h-1. Conversion reached above 90% when the reaction was run up to 120 hours. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

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