Photocatalysis to promote cell-free biocatalytic reactions

Cofactors assist enzymes to catalyze reactions and are indispensable and ubiquitous in nature, playing a central role in metabolic pathways. In biocatalysis, common redox cofactors such as nicotinamide, flavin and heme can be activated by light or synthetized to vary redox potentials, leading to different types of reactions for the formation...

Photochemical regeneration of flavoenzymes – An Old Yellow Enzyme case-study

Direct, NAD(P)H-independent regeneration of Old Yellow Enzymes represents an interesting approach for simplified reaction schemes for the stereoselective reduction of conjugated C=C-double bonds. Simply by illuminating the reaction mixtures with blue light in the presence of sacrificial electron donors enables to circumvent the costly and...

Light-Harvesting Dye-Alginate Hydrogel for Solar-Driven, Sustainable Biocatalysis of Asymmetric Hydrogenation

We report visible light-driven, asymmetric hydrogenation of C=C bonds using an ene-reductase from Thermus scotoductus SA-01 (TsOYE) and a light-harvesting dye (rose bengal, RB) co-immobilized in an alginate hydrogel. Highly efficient encapsulation of RB in alginate hydrogel was achieved using the intrinsic affinity between TsOYE and RB,...

Natural Deep Eutectic Solvents as Performance Additives for Peroxygenase Catalysis

Natural deep eutectic solvents (NADES) are proposed as alternative solvents for peroxygenase-catalysed oxyfunctionalization reactions. Choline chloride-based NADES are of particular interest as they can serve as solvent, enzyme-stabiliser and sacrificial electron donor for the in situ H₂O₂ generation. This report...

Metals in Biotechnology: Cr-Driven Stereoselective Reduction of Conjugated C=C Double Bonds

Elemental metals are shown to be suitable sacrificial electron donors to drive the stereoselective reduction of conjugated C=C double bonds using Old Yellow Enzymes as catalysts. Both direct electron transfer from the metal to the enzyme as well as mediated electron transfer is feasible, although the latter excels by higher reaction rates....

Formate Oxidase (FOx) from Aspergillus oryzae: One Catalyst Enables Diverse H ₂ O ₂ -Dependent Biocatalytic Oxidation Reactions

An increasing number of biocatalytic oxidation reactions rely on H ₂ O ₂ as a clean oxidant. The poor robustness of most enzymes towards H ₂ O ₂ , however, necessitates more efficient systems for in situ H ₂ O ₂ generation. In analogy to the well-known formate dehydrogenase to...

Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media

Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.

Deazaflavins as photocatalysts for the direct reductive regeneration of flavoenzymes

Deazaflavins are potentially useful redox mediators for the direct, nicotinamide-independent regeneration of oxidoreductases. Especially the O₂-stability of their reduced forms have attracted significant interest for the regeneration of monooxygenases. In this contribution we further investigate the photochemical properties of...

Photobiocatalytic alcohol oxidation using LED light sources

The photocatalytic oxidation of NADH using a flavin photocatalyst and a simple blue LED light source is reported. This in situ NAD+ regeneration system can be used to promote biocatalytic, enantioselective oxidation reactions. Compared to the traditional use of white light bulbs this method enables very significant reductions in energy...