β-Carbonic Anhydrases: General Features and Medical Implications

Abstract The β-carbonic anhydrases are a structurally unique class of carbonic anhydrases that is found in a diverse array of microorganisms, algae, plants, and invertebrates. These enzymes are likely associated with other enzymes that consume or produce carbon dioxide (CO 2 ) or bicarbonate (HCO 3 − ), and catalyze the interconversion of these species according to the chemical reaction CO 2 + H 2 O ⇆ HCO 3 − + H + . Evolutionary offshoots of β-carbonic anhydrases hydrolyze the related substances carbonyl sulfide (COS) and carbon disulfide (CS 2 ). In many microorganisms, β-carbonic anhydrases are essential for normal growth. Some β-carbonic anhydrases exhibit allostery, a property not observed in any other class of carbonic anhydrases. As a group, β-carbonic anhydrases are relatively weakly inhibited by sulfonamides and anions, classical inhibitors of most other carbonic anhydrases.