Enzyme engineering breakthrough for immediate deployment in steel industry sites

April 23rd, 2024 • JooHyeon Heo
Figure 1. Tunnel-redesigned CO dehydrogenase. Substituting one residue in a predicted tunnel within CO dehydrogenase-II from Carboxydothermus hydrogenoformans (ChCODH-II) from Ala to Trp can decrease its O2 sensitivity without altering overall catalytic activity. Credit: Nature Catalysis (2022). DOI: 10.1038/s41929-022-00834-y

The research findings were featured on the cover of Nature Catalysis and highlighted in Nature, as well as in collections in Nature Chemical Engineering in 2022 and 2023.

A joint research team, led by Professor Yong Hong Kim and Dr. Suk Min Kim in the Department of Energy and Chemical Engineering and the Graduate School of Carbon Neutrality at UNIST, along with Professor Hyung Ho Lee from the Department of Chemistry at Seoul National University, has achieved a groundbreaking advancement in enzyme engineering. Their research focuses on redesigning Ni–Fe carbon monoxide dehydrogenases (CODHs) to overcome the challenge of oxygen (O2) sensitivity, a critical limitation in industrial applications.

The team's innovative approach involved comparing the structures of two CODH variants: the fast CODH with high O2 sensitivity, ChCODH-II, and the slower CODH with lower O2 sensitivity, ChCODH-IV (Ch, Carboxydothermus hydrogenoformans). Through this comparative analysis, they identified crucial bottleneck residues and successfully engineered a variant (A559W) with significantly reduced O2 sensitivity while maintaining high turnover rates. Molecular dynamics simulations supported their findings, revealing obstruction in a gas tunnel due to a locked position of the mutated side chain.

The engineered enzyme demonstrated remarkable stability and efficiency when exposed to various gas mixtures, including high O2 levels, synthetic gas, and real flue gas from a steel mill. This breakthrough paves the way for utilizing residual carbon-rich gases, such as CO, from the steel industry without the need for prior treatment.

Furthermore, the developed enzyme was successfully employed in the CO hydration reaction, leading to the large-scale production of formic acid. This achievement opens up new possibilities for utilizing not only steel industry by-products, but also gases from coal and plastic waste as valuable resources.

Professor Kim highlighted the practical validation of the enzyme at Hyundai Steel and POSCO sites, emphasizing its potential to advance steel decarbonization initiatives. He stated, "The developed enzyme has undergone direct validation at the facilities of Hyundai Steel and POSCO," highlighting its role in driving steel decarbonization efforts.

More information:
Suk Min Kim et al, O2-tolerant CO dehydrogenase via tunnel redesign for the removal of CO from industrial flue gas, Nature Catalysis (2022). DOI: 10.1038/s41929-022-00834-y

Provided by Ulsan National Institute of Science and Technology