Reductant- or Light-Driven ATP-Independent Reduction of CO2 by Nitrogenase MoFe Protein.

Abstract

Nitrogenase is a versatile metalloenzyme that activates and reduces small molecules like N₂, CO, and CO₂ into value-added chemicals at ambient conditions. Previously, it is shown that the Mo-nitrogenase could reduce CO₂ to CO, but not to hydrocarbons, in an ATP-dependent reaction. Here, it is reported that the ability of the catalytic component of Mo-nitrogenase (MoFe protein) enables ATP-independent reduction of CO₂ to up to C₄ hydrocarbons in room-temperature reactions driven by a chemical reductant (Eu^II-DTPA) or visible light (via CdS@ZnS (CZS) quantum dots). Moreover, an opposite deuterium isotope effect is observed on the Eu^II-DTPA driven reactions of CO₂ reduction by MoFe protein and its V-counterpart (VFe protein), in that the former displays higher activities in H₂O, and the latter displays higher activities in D₂O. These results provide an important foundation for further mechanistic exploration of the nitrogenase-enabled, atypical Fischer-Tropsch type reaction that uses CO₂ instead of CO as a substrate; moreover, they serves as a potential template for the future development of nitrogenase-based applications that effectively recycle the greenhouse gas CO₂ into valuable fuel products.