(2,5)-dihydrocarvone is an industrially applied building block that can be synthesized by site-selective and stereo-selective C=C bond bio-reduction of ()-carvone. ( ) cells overexpressing an ene reductase from sp. PCC7120 (NostocER1) in combination with a cosubstrate regeneration system proved to be very effective biocatalysts for this reaction. However, the industrial applicability of biocatalysts is strongly linked to the catalysts' activity. Since the cell-internal NADH concentrations are around 20-fold higher than the NADPH concentrations, we produced cells where the NADPH-preferring NostocER1 was exchanged with three different NADH-accepting NostocER1 mutants. These whole-cell biocatalysts were used in batch operated stirred-tank reactors on a 0.7 l-scale for the reduction of 300 mM ()-carvone. 287 mM (2,5)-dihydrocarvone were formed within 5 h with a diasteromeric excess of 95.4% and a yield of 95.6%. Thus, the whole-cell biocatalysts were strongly improved by using NADH-accepting enzymes, resulting in an up to 2.1-fold increased initial product formation rate leading to a 1.8-fold increased space-time yield when compared to literature.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6681004 | PMC |
http://dx.doi.org/10.3390/molecules24142550 | DOI Listing |
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