Team:AHUT China/Description
Project Inspiration and Description
In recent years, the application of carbonic anhydrase in CO2 capture has attracted widespread attention and has become an efficient and environmentally friendly strategy. Therefore, we chose carbonic anhydrase as the research object, hoping to explore an efficient and environmentally friendly CO2 capturer.
Carbonic Anhydrase 2
Carbonic Anhydrase 2(CA2) is a zinc-containing metalloenzyme, When the Zn2+ ion abstracts a proton from a surrounding water molecule, creating a hydroxide ion that is negatively charged and can attack the partially positive carbon atom on a solubilised Carbon Dioxide(CO2) molecule to form a HCO3- ion, the hydration of CO2 occurs.
Zn2++H2O⇋H++Zn2+-OH-
Zn2+-OH-+CO2⇋Zn2++HCO3-
The characteristics of CA2 can be used for CO2 capture. Compared with other capture methods, CA2 is specific. It can absorb different concentrations of CO2 in the gas and has higher efficiency than MEA and potassium carbonate. But enzymes need to be immobilizated for industrial use.
Enzyme immobilization
Covalent binding is the most important form of carrier binding, and this chemical reaction process is irreversible. Its principle is that the carrier and the free enzyme can be immobilized through a covalent bond. Its main advantages are that the chemical response conditions are mild and because the carrier and enzyme molecules are connected by covalent bonds, the combination between them is relatively firm, not easy to fall off.
Formylglycine generating enzyme (FGE) can selectively recognize and oxidize the cysteine residues in the sulfatase subunit of the terminal of protein to form formylglycine (FGly) residues containing aldehyde groups. The free aldehyde group on the surface of the target protein can be used for site-specific covalent binding to amino-functionalized fluoresceins or immobilization supports through a Schiff base reaction.
The terminal aldehyde group of CA2, is immobilizated to surface active carriers containing amino groups by covalent binding. This site-specific fixation avoids the chemical degeneration that may occur in common covalent fixation and has higher stability than physical adsorption.
Our project
We made prelimilary progress in the research of CO2 capture by establishing a mutated CA2(CA2(L203K)) last year, and found that the stability and enzyme activity of the mutated CA2 were significantly increased, but no further research and development was carried out. This year, on the basis of last year, we will modify the mutated CA2 gene to obtain genetically engineered expression bacteria that express the CA2 with aldehyde on the protein surface under the reaction of formylglycine-generating enzyme, which in turn binds to the amino group of the immobilized carrier. The immobilization of CA2 is realized to improve its stability, facilitate its repeated use, and achieve industrial application.
Application
For CO2 capture, CA2 is used as a catalyst to accelerate the absorption and desorption rate, greatly improving the efficiency of related processes and reducing the energy consumption required by the processes. Many technologies have successfully captured carbon dioxide emissions from industrial processes such as ammonia synthesis, coal chemical plants, fertilizer plants and power plants. Although a large amount of CO2 is harmful to the ecological environment of the earth, it is also an important industrial raw material. The recovered carbon dioxide can be widely used in the synthesis of organic compounds, as a refrigerant to preserve food, the production of carbonated drinks, as well as directly used in fire fighting, metal protection welding technology and so on.
Reference
[1] Migliardini F, Luca V D, Carginale V, et al. Biomimetic CO2 capture using a highly thermostable bacterial α-carbonic anhydrase immobilized on polyurethane foam [J]. Journal of Enzyme Inhibition and Medicinal Chemistry, 2014, 29(1):146-150.
[2] Hui J, Yingwu W, Yan B, et al. Site-Specific, Covalent Immobilization of Dehalogenase ST2570 Catalyzed by Formylglycine-Generating Enzymes and Its Application in Batch and Semi-Continuous Flow Reactors [J]. Molecules, 2016, 21(7):895.
[3] Rahman F A, Aziz M M A, Saidur R, et al. Pollution to solution: Capture and sequestration of carbon dioxide (CO2) and its utilization as a renewable energy source for a sustainable future [J]. Renewable & Sustainable Energy Reviews, 2017, 71:112-126.
[4] Lionetto M G, Caricato R, Erroi E, et al. Potential application of carbonic anhydrase activity in bioassay and biomarker studies [J]. Chemistry & Ecology, 2006, 22(sup1): S119-S25.
[5] Bond G M, Stringer J, Brandvold D K, et al. Development of Integrated System for Biomimetic CO2 Sequestration Using the Enzyme Carbonic Anhydrase [J]. Energy & Fuels, 2001, 15(2):309-316.
[6] Yong J K J, Stevens G W, Caruso F, et al. The use of carbonic anhydrase to accelerate carbon dioxide capture processes [J]. Journal of Chemical Technology & Biotechnology, 2015, 90(1):3-10.
