Towards electroenzymatic processes involving old yellow enzymes and mediated cofactor regeneration

Abstract

Old yellow enzymes are able to catalyze asymmetric C=C reductions. A mediated electroenzymatic process to regenerate the NADPH in combination with an old yellow enzyme was investigated. Due to the fact that the overall process was affected by a broad set of parameters, a design of experiments (DoE) approach was chosen to identify suitable process conditions. Process conditions with high productivities of up to 2.27 mM/h in combination with approximately 90% electron transfer efficiency were identified.

Characterization of the Old Yellow Enzyme Homolog from Bacillus subtilis (YqjM)

“…Protonation of the resulting anion occurs from the opposite face of the C=C-double bond through a tyrosine moiety; overall resulting in a trans-hydrogenation. This catalytic mechanism also enables regeneration pathways independent from the natural nicotinamide cofactor such as substratecoupled regeneration, [4] use of synthetic reductants [5] and electrochemical [6] or photochemical regeneration. [7] Furthermore, OYE are currently experiencing an increasing interest from the catalysis community for the preparation of enantiomerically pure compounds from simple (prochiral) conjugated C=C-double bonds.…”

“…Protonation of the resulting anion occurs from the opposite face of the C=C‐double bond through a tyrosine moiety; overall resulting in a trans ‐hydrogenation. This catalytic mechanism also enables regeneration pathways independent from the natural nicotinamide cofactor such as substrate‐coupled regeneration, use of synthetic reductants and electrochemical or photochemical regeneration…”

Discovery, Characterization, Engineering, and Applications of Ene-Reductases for Industrial Biocatalysis

“…94 Electroenzymatic synthesis is a less well studied biotransformation in which a cofactor or cosubstrate is regenerated by an electrochemical reaction in the presence of chemical mediators. 95 The OYE-catalyzed bioreduction of (−)-carvone to (+)-dihydrocarvone was investigated, where NADPH regeneration was performed electrochemically in the presence of the mediator [Cp*Rh(bpy)(H 2 O)] 2+ , cobalt sepulchrate, or safranin T. 96 High productivities and high current efficiencies (∼90%) were achieved, but only under anaerobic conditions, as the required mediator reduction potentials are more negative than the O 2 reduction potential. 96 Photosynthetic organisms utilize solar energy to catalyze the reduction of carbon dioxide to carbohydrates, concomitant with the reduction of nicotinamide cofactors.…”

Enzymatic Bioreactors: An Electrochemical Perspective

“…Badalyan et al used the negatively charged viologen derivative [(SPr) 2 V • ]¯as an effective mediator for nitrogenase electrocatalysis [54]. Tosstorff et al used three different mediators, cobalt sepulchrate, safranin T, and [Cp*Rh(bpy)(H 2 O)] 2+ in an NADH regeneration system that was combined with old yellow enzyme for the asymmetric reduction of C=C [55].…”

“…Catalysts 2020, 10, x 3 of 25 mediators, cobalt sepulchrate, safranin T, and [Cp * Rh(bpy)(H2O)] 2+ in an NADH regeneration system that was combined with old yellow enzyme for the asymmetric reduction of C=C [55].…”