Biocatalytic cofactor regeneration for CO2 reduction: Integration of a hydrogenase and a formate dehydrogenase in H2-driven systems

Abstract

Formate dehydrogenases catalyze the reversible oxidation of formate to carbon dioxide. These enzymes play an important role in CO2 reduction and serve as nicotinamide cofactor recycling enzymes. More recently, the CO2-reducing activity of formate dehydrogenases, especially metal-containing formate dehydrogenases, has been further explored for efficient atmospheric CO2 capture. In this sense, molecular hydrogen (H2) as the fuel of the future represents an efficient, cheap and environmentally friendly reducing agent when produced from renewable sources. Hydrogenases are enzymes that catalyze the reversible oxidation of H2. Herein, the functional interplay between the soluble [NiFe] hydrogenase from Cupriavidus necator and the molybdenum-dependent formate dehydrogenase from Rhodobacter capsulatus was investigated in a coupled biocatalytic system. H2-driven CO2 reduction (H2CO2R) using methyl viologen as an artificial electron mediator gave a higher product yield of formate than using NAD+ as the physiological electron mediator. The enzymes were stable under anaerobic conditions for 18 h, making the coupled reaction suitable for biotechnological purposes.

Keywords

• Formate
• Carbon dioxide
• Molybdenum
• Iron-sulfur
• Cascade reaction