Carbonic anhydrase II

Carbonic anhydrase II (CA II) is an enzyme that belongs to the family of carbonic anhydrases, which are zinc-containing metalloenzymes. These enzymes catalyze the reversible hydration of carbon dioxide, a crucial reaction in many physiological processes.

Structure

Carbonic anhydrase II is a monomeric protein with a molecular weight of approximately 29 kDa. It is characterized by a single zinc ion in its active site, which is essential for its enzymatic activity. The enzyme's structure is highly conserved across different species, reflecting its fundamental role in biological systems.

Function

CA II is one of the most active carbonic anhydrases and is found in high concentrations in red blood cells, kidneys, and the gastrointestinal tract. It facilitates the rapid conversion of carbon dioxide and water to bicarbonate and protons, a reaction that is vital for maintaining acid-base balance in tissues and organs.

Physiological Roles

• Respiratory System: In the lungs, CA II helps convert bicarbonate back to carbon dioxide for exhalation.
• Renal System: In the kidneys, it plays a role in acid-base homeostasis by reabsorbing bicarbonate from urine.
• Digestive System: In the stomach, it contributes to the production of gastric acid by providing protons.

Clinical Significance

Mutations in the gene encoding carbonic anhydrase II can lead to a rare genetic disorder known as osteopetrosis, which is characterized by increased bone density and other systemic symptoms. CA II deficiency can also result in renal tubular acidosis, a condition where the kidneys fail to acidify urine properly.

Inhibitors

Carbonic anhydrase inhibitors, such as acetazolamide, are used clinically to treat conditions like glaucoma, epilepsy, and altitude sickness. These inhibitors work by reducing the activity of CA II, thereby affecting fluid secretion and pH balance.

Research and Applications

CA II is a target for drug development due to its involvement in various diseases. Research is ongoing to develop more selective inhibitors that can modulate its activity without affecting other isoforms of carbonic anhydrase.

Also see

• Carbonic anhydrase
• Zinc metalloenzyme
• Acid-base homeostasis
• Osteopetrosis
• Renal tubular acidosis