Quantum chemical studies of the reaction mechanisms of enzymatic CO₂ conversion

Enzymatic capture and conversion of carbon dioxide (CO₂) into value-added chemicals are of great interest in the field of biocatalysis and have a positive impact on climate change. The quantum chemical methods, recognized as valuable tools for studying reaction mechanisms, have been widely employed in investigating the reaction mechanisms of the enzymes involved in CO₂ utilization. In this perspective, we review the mechanistic studies of representative enzymes that are either currently used or have the potential for converting CO₂, utilizing the quantum chemical cluster approach and the quantum mechanical/molecular mechanical (QM/MM) method. We begin by summarizing current trends in enzymatic CO₂ conversion, followed by a brief description of the computational details of quantum chemical methods. Then, a series of representative examples of the computational modeling of biocatalytic CO₂ conversion are presented, including the reduction of CO₂ to C1 species (carbon monoxide and formate), and the fixation of CO₂ to form aliphatic and aromatic carboxylic acids. The microscopic views of reaction mechanisms obtained from these studies are helpful in guiding the rational design of current enzymes and the discovery of novel enzymes with enhanced performance in converting CO₂. Additionally, they provide key information for the de novo design of new-to-nature enzymes. To conclude, we present a perspective on the potential combination of machine learning with quantum description in the study of enzymatic conversion of CO₂.