Carbonic anhydrase

Carbonic anhydrase is a family of enzymes that catalyze the rapid interconversion of carbon dioxide and water to bicarbonate and protons (or vice versa), a reaction that occurs rather slowly in the absence of a catalyst.

Function

Carbonic anhydrase helps regulate pH and fluid balance in various parts of the body. It is found in a variety of tissues, including red blood cells, the kidneys, and the eyes. In the kidney, it helps reabsorb bicarbonate, a key component of the blood buffer system. In the eye, it helps produce aqueous humor, the fluid that fills the anterior chamber of the eye.

Types

There are several types of carbonic anhydrase, which are classified based on their structural characteristics. These include:

• Carbonic anhydrase I (CA I), which is found primarily in red blood cells.
• Carbonic anhydrase II (CA II), which is found in many tissues, including the kidneys and the eyes.
• Carbonic anhydrase III (CA III), which is found in skeletal muscle.
• Carbonic anhydrase IV (CA IV), which is found on the surface of endothelial cells in the lungs and kidneys.

Clinical significance

Mutations in the genes that encode carbonic anhydrase can lead to a variety of disorders. For example, mutations in the gene for CA II can cause osteopetrosis (a condition characterized by dense, brittle bones), renal tubular acidosis (a condition characterized by acidic blood), and cerebral calcification (a condition characterized by calcium deposits in the brain).

Inhibitors of carbonic anhydrase, such as acetazolamide, are used to treat conditions such as glaucoma, epilepsy, and altitude sickness.

See also

• Enzyme
• Catalysis
• Acid-base homeostasis

References

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  Human carbonic anhydrase II structure
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  Mechanism of carbonic anhydrase II
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  Active site of carbonic anhydrase II
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  Active site of carbonic anhydrase 1CA2
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  Carbonic anhydrase II enzyme
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  Structure of carbonic anhydrase 1CA2
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  Ligands and pocket style of carbonic anhydrase