Hydrophobic modifications of carbonic anhydrase distinctly improve performance in biocatalytic carbon capture

The enzyme carbonic anhydrase (CA) can accelerate gas-liquid mass transfer of CO 2 , and extensive research is exploring how to leverage this in industrial carbon capture. At the molecular level, CA promotes capture by catalyzing the conversion of CO 2 to bicarbonate near the gas-liquid interface. This mechanism implies that only a minor fraction of the enzyme at the interface actively contributes to capture, and as a result, efficient capture requires high enzyme dosages. Here, we designed and synthesized CA variants with hydrophobic modifications intended to make them interfacially active. The modified enzymes showed dramatic improvements in capture performance. In a stirred-cell setup, the capture rate observed for the wild-type CA could be matched with a modified-enzyme dosage of less than 0.3% of the wild-type enzyme dosage. This corresponded to a 400-fold increase in specific activity after acylation. In a packed column system, the modified enzymes matched the performance of the wild type at only 3.3% of the wild-type enzyme dosage. Enzyme modifications only marginally affected thermostability and intrinsic enzyme activity in the aqueous bulk, and we proposed that the improved CO 2 capture efficacy of the modified enzymes reflected a general surface-partitioning mechanism. This interpretation provided fundamental insights into the interfacial enzyme process and potentially highlighted a novel, broad avenue for designing catalysts for CO 2 capture.