Expanding the Biocatalytic Toolbox with a New Type of ene/yne‐Reductase from Cyclocybe aegerita.

This study introduces a new type of ene/yne‐reductase from Cyclocybe aegerita with a broad substrate scope including aliphatic and aromatic alkenes/alkynes from which aliphatic C8‐alkenones, C8‐alkenals and aromatic nitroalkenes were the preferred substrates. By comparing alkenes and alkynes, a ∼2‐fold lower conversion towards alkynes was observed. Furthermore, it could be shown that the alkyne reduction proceeds via a slow reduction of the alkyne to the alkene followed by a rapid reduction to the corresponding alkane. An accumulation of the alkene was not observed. Moreover, a regioselective reduction of the double bond in α,β‐position of α,β,γ,δ‐unsaturated alkenals took place. This as well as the first biocatalytic reduction of different aliphatic and aromatic alkynes to alkanes underlines the novelty of this biocatalyst. Thus with this study on the new ene‐reductase CaeEnR1, a promising substrate scope is disclosed that describes conceivably a broad occurrence of such reactions within the chemical landscape. [ABSTRACT FROM AUTHOR]