Biocatalytic CO2 Absorption and Structural Studies of Carbonic Anhydrase under Industrially-Relevant Conditions

Abstract

The unprecedently high CO2 levels in the atmosphere evoke the urgent need for development of technologies for mitigation of its emissions. Among the alternatives, the biocatalytic route has been claimed as one of the most promising. In the present work, the carbonic anhydrase from bovine erythrocytes (BCA) was employed as a model enzyme for structural studies in an aqueous phase at alkaline pH, which is typical of large-scale absorption processes under operation. Circular dichroism (CD) analysis revealed a high enzymatic stability at pH 10 with a prominent decrease of the melting temperature above this value. The CO2 absorption capacity of the aqueous solutions were assessed by online monitoring of pressure decay in a stainless-steel cell, which indicated a better performance at pH 10 with a kinetic rate increase of up to 43%, as compared to non-biocatalytic conditions. Even low enzyme concentrations (0.2 mg g−1) proved to be sufficient to improve the overall CO2 capture process performance. The enzyme-enhanced approach of CO2 capture presents a high potential and should be further studied.

Artificial Carbonic Anhydrase-Ruthenium Enzyme for Photocatalytic Water Oxidation

“…Similar values found for BCA-Ru1 , BCA-Ru2 , and BCA-Ru4 , and the twice lower value found for BCA-Ru3 , were consistent with the 1:2 Ru/Zn ratio found for BCA-Ru3 by ICP–MS (see above), while all other ArMs had a 1:1 Ru/Zn ratio. The CD spectra of the ArMs showed a more surprising result (Figure S13): for BCA-Ru1 , there was no significant change of the conformation of the protein, while for BCA-Ru2 , BCA-Ru3 , and BCA-Ru4 binding of the metal complex to BCA did affect significantly the secondary structure of the protein, notably around 215 and 225 nm, which are related to the antiparallel β-sheet and α-helix domains of BCA . Overall, all the synthesized complexes showed a strong interaction with BCA but Ru1 had the best complex-protein interaction with BCA in the studied conditions.…”

“…Artificial metalloenzymes (ArMs) are man-made proteins obtained by the conjugation of an artificial metal-based cofactor to a well-identified protein. − In modern chemistry, ArMs have appeared as an essential tool toward the development of more efficient and faster catalytic reactions that cannot be catalyzed, or are less efficiently catalyzed, by natural enzymes . They also allow for exploring the behavior of water-insoluble artificial catalysts in aqueous environments. − Among the diverse proteins used for the making of ArMs, bovine carbonic anhydrase ( BCA ) has proven to be a versatile scaffold capable of hosting diverse synthetic cofactors. − The mainly hydrophobic substrate-binding pocket of the BCA protein is constituted by three histidine residues coordinated facially to a Zn 2+ ion. In cells, this protein is capable of catalyzing the hydration of CO 2 gas into H 2 CO 3 , which plays a critical role in the control of pH and of dissolved CO 2 levels inside blood, cells, and tissues .…”

Design of Enzyme Loaded W/O Emulsions by Direct Membrane Emulsification for CO2 Capture

“…The dispersed phase consisted of ultrapure MilliQ ® IQ water along with the carbonic anhydrase enzyme as the functional compound. Carbonic anhydrase has been reported to have high enzymatic activity at ~pH 10-11 [30]. Therefore, the pH of the dispersed phase was accordingly adjusted using potassium carbonate salt.…”

Theoretical study of transition metal-doped β12 borophene as a new single-atom catalyst for carbon dioxide electroreduction

“…The conversion of CO 2 into high value-added chemicals, with the potential to mitigate atmospheric CO 2 levels and generate substantial economic gains, has garnered increasing research attention. 1–4 Existing CO 2 conversion technologies mainly include biocatalytic conversion, 5 thermal catalytic conversion, 6 photocatalytic conversion 7 and electrocatalytic conversion. 8 Among these methods, the electrochemical CO 2 reduction reaction (CO 2 RR) shows a wide range of applications because of its cost-effectiveness and environmental friendliness.…”