Electrifying Biotechnology

Electroenzymatic processes leverage the high selectivity of enzymes as biocatalysts, coupled with the electrochemical regeneration of their cofactors [1-4]. This approach holds promise for developing new biotechnological processes for both fine and bulk chemical production. This project, part of the German Research Foundation's priority programme "Bioelectrochemical and Engineering Foundations for Establishing Electrobiotechnology for Biosynthesis - Power to Value-added Products (eBiotech) (SPP 2240)," addresses current bottlenecks in electroenzymatic processes, such as product scale, productivity, and the efficiency of cofactor regeneration.

The goal is to design porous 3-D enzymatic electrodes that incorporate a novel enzymatic cascade with electrochemical nicotinamide adenine dinucleotide phosphate (1,4-NAD(P)H) cofactor regeneration. The project will consider model enzymatic cascades with chiral lactones as target compounds, which can also serve as polymer precursors. Direct electrochemical NAD(P)+ reduction (NADRR) is a promising yet challenging approach, with the main difficulties lying in the selectivity and stability of the electrochemical cofactor regeneration systems, as well as their productivity. Recently, the feasibility of bioelectrochemical synthesis combining enoate reductase and direct NADRR under pulsed conditions has been demonstrated [5].

Figure 1: The schematic illustrates the direct electrochemical regeneration of 1,4-NADH under varying operating conditions, steady-state and dynamic, at the surface of a porous carbon-based electrode. Dynamic operation accelerates the regeneration of 1,4-NADH, demonstrating its potential for integration with an enzymatic reaction that converts cyclohexenone to cyclohexanone using enoate reductase. This work was featured on the front cover [6]. — **Figure 1:** The schematic illustrates the direct electrochemical regeneration of 1,4-NADH under varying operating conditions, steady-state and dynamic, at the surface of a porous carbon-based electrode. Dynamic operation accelerates the regeneration of 1,4-NADH, demonstrating its potential for integration with an enzymatic reaction that converts cyclohexenone to cyclohexanone using enoate reductase. This work was featured on the front cover [6].

**Figure 1:** The schematic illustrates the direct electrochemical regeneration of 1,4-NADH under varying operating conditions, steady-state and dynamic, at the surface of a porous carbon-based electrode. Dynamic operation accelerates the regeneration of 1,4-NADH, demonstrating its potential for integration with an enzymatic reaction that converts cyclohexenone to cyclohexanone using enoate reductase. This work was featured on the front cover [6].

Funding: DFG

Collaborations:

Prof. Bornscheuer, University of Greifswald
Prof. E. Haak, OVGU
Dr. T.-P. Fellinger, BAM

Selected recent publications:

[1] Vidaković-Koch T. (2018) Habilitation Thesis, Otto von Guericke University, Magdeburg, 2018, doi: 10.25673/14087.08.02.

[2] Vidakovic-Koch, T. (2019) Electron Transfer Between Enzymes and Electrodes, in Bioelectrosynthesis, F. Harnisch and D. Holtmann, Editors. Springer International Publishing: Cham. p. 39-85.

[3] Varničić, M., Zasheva, I.N., Haak, E., Sundmacher, K., and Vidaković-Koch, T. (2020) Selectivity and Sustainability of Electroenzymatic Process for Glucose Conversion to Gluconic Acid. Catalysts, 10(3), 269 doi.org/10.3390/catal10030269

[4] Varničić, M., Fellinger, T.-P., Titirici, M.-M., Sundmacher, K., & Vidaković-Koch, T. (2024) Rational Design of Enzymatic Electrodes: Impact of Carbon Nanomaterial Types on the Electrode Performance Molecules, 29 (10), 2324 doi: 10.3390/molecules29102324.

[5] Al-Shaibani, M. A. S., Sakoleva, T., Živković, L. A., Austin, H. P., Dörr, M., Hilfert, L., Haak, E., Bornscheuer, U. T., & Vidaković-Koch, T. (2024) Product Distribution of Steady–State and Pulsed Electrochemical Regeneration of 1,4‐NADH and Integration with Enzymatic Reaction ChemistryOpen, 13 (8), e202400064 doi: 10.1002/open.202400064.

[6] Al-Shaibani, M. A. S., Sakoleva, T., Živković, L. A., Austin, H. P., Dörr, M., Hilfert, L., Haak, E., Bornscheuer, U. T., & Vidaković-Koch, T. (2024) Front Cover: Product Distribution of Steady–State and Pulsed Electrochemical Regeneration of 1,4‐NADH and Integration with Enzymatic Reaction (ChemistryOpen 8/2024) ChemistryOpen, 13 (8), e202480801 doi:10.1002/open.202480801