Carboanhydrase

Industrial uses

Carboanhydrases are enzymes that catalyse the hydrolysis of carbon dioxide. These enzymes are involved in many biological processes such as photosynthesis (CO₂ uptake), respiration (CO₂ release) and pH control.
The human carboanhydrase, form II(c), consists of 259 amino acids with a molecular weight of around 30 kDa. The catalytic site contains a Zn²⁺ ion which is coordinated by three neutral histidine (His) residues and a water molecule. The water molecule is believed to be important for structural reasons and enzymatic functionality .In a first step (i), a proton is transferred to His64 from the coordinated water molecule. In a second step (ii), a buffer molecule (B) coordinates this proton and transports it away from the active site. The remaining hydroxide ligand reacts quickly and forms a transition state via hydrogen bonding with CO₂ (iii). Following some more transformations, HCO₃^- is released as it is replaced by another molecule of water (iv) and (v).