De novo Design of Peptide Catalyst as Enzyme-mimic for Carbon Dioxide Sequestration

Enzymes are natural catalysts. They play an important role in a series of biological processes by catalysing reactions with high degree of specificity and efficiency. Inspired by the high degree of selectivity, modified enzymes or their peptide mimics have been used in recent times for applications across different fields, including biotechnology, pharmacology and environmental science. The peptide sequence as possible alternative essentially mimics the enzyme active site. Their diversity in sequence selection and flexibility of structure have shown to be a promising alternative for enzymes, especially in harsh conditions such as high temperature and extreme pH.

Natural carbonic anhydrases catalyze the reversible conversion of CO₂ and water to bicarbonate (HCO₃⁻) and protons (H⁺). The goal is to design synthesize and characterize synthetic catalysts mimicking enzymes that can catalyse reaction even at extreme conditions, potentially aiding in the capture of CO₂ from the atmosphere or industrial emissions. In this work, we attempt to mimic human carbonic anhydrase II enzyme, with four heptapeptides, Ac-HyHyHfF-CONH₂, Ac-HPhYhFf-CONH₂, Ac-HhHfFyF-CONH₂ and Ac-HhYfHfF-CONH₂. Its catalytic activity was found to have remarkably increased with increase in pH and temperature. The conversion of carbon dioxide to bicarbonate was monitored by evaluating the change in pH in the presence of different catalysts and control. The results indicate that Ac-HyHyHfF-CONH2 exhibited the best catalytic performance among the four Zn-heptapeptide. This resulted in investigating further to employ such peptides for potential applications in carbon dioxide sequestration.

Capturing and storing atmospheric carbon dioxide either ‘geologic’ or ‘biologic’ processes is the need of the hour.  In this work we explored the possibility of hybridizing these diverse disciplines by making use of molecules of ‘biological’ origin for storing carbon dioxide in ‘geological’ formations.