Fig. 1.

Carbonic anhydrase enzyme and its CO₂ capture and regeneration mechanism. a Ribbon representation of the carbonic anhydrase (CA) enzyme. b Active site of CA determined by molecular simulations (vide infra). A zinc ion (Zn²⁺) surrounded by three coordinating histidines and a water molecule comprises the active site. c Depiction of the overall catalytic cycle for CO₂ hydration to HCO₃^– with zinc as the metal in the CA active site. This reaction is driven by a concentration gradient: clockwise when the CO₂ concentration is greater than HCO₃^– and counterclockwise when more HCO₃^– is present. Deprotonation of the zinc-bound water is thought to be rate limiting