Süsinikterases

Süsinikterases, also known as carbonic anhydrases, are a family of enzymes that catalyze the rapid interconversion of carbon dioxide and water to bicarbonate and protons. This reversible reaction is crucial for a wide range of physiological processes in virtually all living organisms. The general reaction catalyzed by carbonic anhydrases is CO2 + H2O <=> H2CO3 <=> H+ + HCO3-.

These enzymes are metalloenzymes, meaning they require a metal ion cofactor for their activity. In most known carbonic anhydrases, this metal ion is zinc (Zn2+). The zinc ion is coordinated by three histidine residues and a water molecule, which is then deprotonated to form a zinc-bound hydroxide. This hydroxide then attacks the carbon atom of carbon dioxide, forming bicarbonate.

Carbonic anhydrases play vital roles in diverse biological functions. In respiration, they facilitate the transport of carbon dioxide from tissues to the lungs for exhalation. They are also involved in maintaining acid-base balance in the blood, bone resorption, gluconeogenesis, and the secretion of electrolytes. In plants, carbonic anhydrases are important for photosynthesis, concentrating carbon dioxide around the enzyme RuBisCO.

The carbonic anhydrase family is diverse, with many different isoforms identified in various species. These isoforms often exhibit different tissue distributions, catalytic rates, and substrate specificities, reflecting their specialized roles. Due to their widespread importance, carbonic anhydrases are targets for drug development, particularly in treating conditions like glaucoma and epilepsy, where modulating their activity can have therapeutic benefits.