Multienzyme Complex System for Cascade Biotransformation of Ammonia and Carbon Dioxide

The extensive use of fossil fuels has caused a sharp increase in atmospheric carbon dioxide (CO₂) concentrations, and carbon capture, utilization, and storage (CCUS) methods are considered to be a promising approach. Enzymes have gained attention in the CCUS field due to their mild reaction conditions, high catalytic efficiency, and environmental friendliness. Among these, carbonic anhydrase (CA) effectively enhances the CO₂ absorption efficiency. Building on CA’s role, the subsequent utilization of hydrated bicarbonate (HCO₃^–) is implemented to achieve CCUS objectives. Experiments identified a hyperthermophilic enzyme, Pyrococcus furiosus carbamate kinase (CK-Pf), which converts CO₂ into value-added products through green processes while removing environmental pollutant ammonia. An in vitro multienzyme cascade pathway was designed: CA first hydrates CO₂ to HCO₃^–, after which CK-Pf converts ammonia and HCO₃^– to carbamoyl phosphate (CP) via carbamate in an ATP-dependent manner. Aspartate transcarbamoylase (ATC) then converts CP to n-carbamoyl-l-aspartate (n-CP-l-Asp). A one-pot multienzyme system demonstrated high activity between 50 and 80 °C, achieving a CO₂ conversion rate of 5.70%. This multienzyme cascade establishes a green CCUS route, offering a feasible technical solution for reducing NH₃ and CO₂ emissions while enabling resource utilization.