Light-driven Oxidative Demethylation Reaction Catalyzed by a Rieske-type Non-heme Iron Enzyme Stc2

Area of Science:

• Biocatalysis
• Photochemistry
• Enzyme Engineering

Background:

• Rieske-type non-heme iron oxygenases/oxidases are versatile biocatalysts.
• Current applications are limited by the requirement for expensive NAD(P)H and specific reductase enzymes for electron transfer.

Purpose of the Study:

• To develop a cost-effective and efficient alternative to the NAD(P)H-dependent system for Rieske-type oxygenases.
• To explore the use of photocatalysis to drive enzymatic reactions, bypassing traditional reductants.

Main Methods:

• Utilized eosin Y as a photosensitizer and sulfite as a sacrificial reagent for photo-reduction.
• Employed a flow-chemistry setup to separate photo-reduction and oxidation half-reactions.
• Tested the system with Rieske-type oxygenase Stc2 and other redox enzymes like NdmA, CntA, GbcA, and IYD.

Main Results:

• The Stc2 photocatalysis system effectively replaced the need for NAD(P)H and reductase (GbcB).
• Photocatalysis in a flow-chemistry setting demonstrated superior performance compared to the conventional NAD(P)H-dependent system.
• The eosin Y/sulfite system successfully supported catalysis in other tested Rieske and flavin-dependent enzymes.

Conclusions:

• Developed a novel photocatalytic approach for Rieske-type oxygenases using eosin Y/sulfite.
• This method circumvents the need for expensive NAD(P)H and dedicated reductases, offering a more sustainable biocatalysis solution.
• The photo-reduction system shows broad applicability to various redox enzymes, indicating significant potential for future biocatalytic applications.