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. 2023 Oct 5;135(52):e202309305. doi: 10.1002/ange.202309305

Figure 3.

Figure 3

CO2 capture and utilisation. A) Schematic active site depiction of a β‐carbonic anhydrase (CA). B) CA can be used as a catalyst in carbon capture and sequestration (CSS) technologies to extract CO2 from flue gas as bicarbonate. CA also accelerates CO2 release at low temperatures. [28] C) CA from D. vulgaris (DVCA) was improved over nine rounds of directed evolution to increase enzyme tolerance to harsh process conditions. Overall, a 4×106‐fold improvement in enzyme performance was achieved. [28] D) The TaCo pathway is a synthetic metabolic pathway for fixation of CO2, resulting in the formation of glycerate. This pathway can be interfaced with the CETCH cycle.[ 31 , 32 ] (Enzyme and cofactor diagram abbreviations: ACS=acetyl‐CoA synthetase, GCC=glycolyl‐CoA carboxylase, GCS=glycolyl‐CoA synthase, TCR=tartronyl‐CoA reductase, MePCC=M. extorquens propionyl‐CoA carboxylase, NADP=nicotinamide adenine dinucleotide phosphate). E) The ASAP pathway is a chemo‐enzymatic cascade reaction for production of starch. Following the chemical reduction of CO2 to methanol, a 10‐enzyme cascade converts C1 compounds to starch. Enzymes highlighted in red were identified as bottlenecks in this pathway and subjected to engineering to improve cascade efficiency. [33] The protein structure shows formolase (FLS), [34] which is a computationally designed enzyme (PDB: 4QQ8) based on benzaldehyde lyase (BAL). Blue spheres indicate mutations introduced by computational design, red spheres indicate mutations discovered through mutagenesis and screening, and purple spheres indicate positions that were targeted by computation and mutagenesis. FLS catalysis is mediated by a TPP cofactor, shown in cyan. (Enzyme and cofactor diagram abbreviations: AGP=ADP‐glucose pyrophosphorylase, ADP=adenosine 5′‐diphosphate, AOX=alcohol oxidase, ATP=adenosine 5′‐triphosphate, BAL=benzaldehyde lyase, DAK=dihydroxyacetone kinase, FBA=Fructose‐bisphosphate aldolase, FBP=fructose‐bisphosphatase, FLS=formolase, PGI=phosphoglucose isomerase, PGM=phosphoglucomutase, SS=starch synthase, TPI=triose‐phosphate isomerase, Chemical compound abbreviations: ADPG=ADP glucose, DHAP=dihydroxyacetone phosphate, GAP=D‐glyceraldehyde 3‐phosphate, F‐1,6‐BP=D‐fructose‐1,6‐bisphosphate, F‐6‐P=D‐fructose‐6‐phosphate, G‐6‐P=glucose‐6‐phosphate, G‐1‐P=α‐D‐glucose‐1‐phosphate, Pi=inorganic phosphate, PPi=pyrophosphate).