Challenges in capturing oxygenase activity in vitro

Abstract Biocatalysis using oxygenase or desaturase enzymes has the potential to add value to native fats and oils by adding oxygen, hydroxyl groups, or double bonds to create regio‐ and/or stereospecific products. These enzymes are a subset of the large class of oxidoreductase enzymes (from EC subgroups 1.13 and 1.14) involved with biological oxidation and reduction. In vitro biocatalytic processing using these enzymes is hampered by the high cost of the stoichiometric cofactors. This article reviews recent progress in developing in vitro redox enzyme biocatalysis for commercial‐scale syntheses. Coenzyme recycling and electrochemical redox cycling as methods for cofactor regeneration are described and commercial applications indicated. Direct charge transfer without use of mediators is described as the cleanest way of introducing the reducing power into the catalytic cycle. Our electrochemically driven cytochrome P450 cam bioreactor is discussed as an example of direct charge transfer to a redox protein. Site‐directed mutagenesis in the active site of the P450 cam monooxygenase greatly improved performance for the conversion of the nonnative substrate, styrene to styrene oxide. This epoxidation reaction was also shown to give a single product (styrene oxide) in the bioelectrochemical reactor when the diatomic oxygen co‐substrate was managed properly.