Inhibition of the Archaeal β-Class (Cab) and γ-Class (Cam) Carbonic Anhydrases

Five independently evolved classes (α-, β-, γ-, δ-, ζ-) of carbonic anhydrases facilitate the reversible hydration of carbon dioxide to bicarbonate of which the α-class is the most extensively studied. Detailed inhibition studies of the α-class with the two main classes of inhibitors, sulfonamides and metal-complexing anions, revealed many inhibitors that are used as therapeutic agents to prevent and treat many diseases. Recent inhibitor studies of the archaeal β-class (Cab) and the γ-class (Cam) carbonic anhydrases show differences in inhibition response to sulfonamides and metal-complexing anions, when compared to the α-class carbonic anhydrases. In addition, inhibition between Cab and Cam differ. These inhibition patterns are consistent with the idea that although, α-, β-, and γ-class carbonic anhydrases participate in the same two-step isomechanism, diverse active site architecture among these classes predicts variations on the catalytic mechanism. These inhibitor studies of the archaeal β- and γ-class carbonic anhydrases give insight to new applications of current day carbonic anhydrase inhibitors, as well as direct research to develop new compounds that may be specific inhibitors of prokaryotic carbonic anhydrases.