Increased thermal stability of the carbonic anhydrase enzyme complex for the efficient reduction of CO2 through cyclization and polymerization by peptide bonding

Abstract

SpyCatcher and SpyTag, which form spontaneous isopeptide bonds, provide thermal and structural stability to enzymes. A Catcher/Tag system was introduced into the carbonic anhydrase (hmCA) from Hydrogenovibrio marinus to perform enzyme cyclization and polymer formation. This allows the enzyme to withstand high temperatures of 60 ℃ or higher when used as a method to reduce CO2. A measurement of thermal stability in response to temperature change showed that the wild-type enzyme exhibited a sharp decrease in activity recovery starting at 70 ℃, but that cyclic hmCA and polymeric hmCA recovered even at 100 ℃. These results indicate that the spontaneous isopeptide bond introduced by the Catcher/Tag system provides thermal stability in enzymes. Regarding the amount of CaCO3 synthesized by the carbonic anhydrases, the result for polymeric hmCA was more than four times higher than for wild-type hmCA. In conclusion, this study succeeded in preparing a heat-resistant carbonic anhydrase that can act at high temperatures where the wild-type enzyme is inactivated. We also show that the enzyme has the advantage of increasing CaCO3 production. These results will provide a CO2 capture system for coal- and natural gas-fired power plants as a way to reduce CO2 emissions.