Nicotinamide‐Dependent Ene Reductases as Alternative Biocatalysts for the Reduction of Activated Alkenes

Abstract

Abstract Four NAD(P)H‐dependent non‐flavin ene reductases have been investigated for their ability to reduce activated C=C bonds in an asymmetric fashion by using 20 structurally diverse substrates. In comparison with flavin‐dependent Old Yellow Enzyme homologues, a higher degree of electronic activation was required, because the best activities were obtained with enals and nitroalkenes rather than enones and carboxylic esters. Although FaEO from Fragaria x ananassa (strawberry) and its homologue SlEO from Solanum lycopersicum (tomato) exhibited a narrow substrate spectrum, progesterone 5β‐reductase (At5β‐StR) from Arabidopsis thaliana (thale cress) and leukotriene B 4 12‐hydroxydehydrogenase (LTB 4 DH/PGR) from Rattus norvegicus (rat) appear to be promising candidates, in particular for the asymmetric bioreduction of open‐chain enals, nitroalkenes and α,β‐unsaturated γ‐butyrolactones. Competing nitro reduction and non‐enzymatic Weitz–Scheffer epoxidation were largely suppressed.