Carbonic anhydrase II (CA II) is a metalloenzyme found in various tissues and cells of organisms, particularly in the erythrocytes, which plays a crucial role in regulating acid-base balance and catalyzing the reversible hydration reaction of carbon dioxide (CO2) to bicarbonate (HCO3-) ions. It is highly abundant in red blood cells (RBCs) and renal tubular epithelial cells.
The enzyme carbonic anhydrase II consists of a single polypeptide chain containing around 259 amino acids. It contains a catalytic zinc ion coordinated to three histidine residues and a water molecule, forming the active site necessary for the enzyme's function.
Carbonic anhydrase II facilitates the conversion of CO2 and H2O into HCO3- and H+, accelerating the reaction by thousands of times. This reaction is vital for maintaining pH balance in blood plasma and other tissues, as well as for the transport of CO2 from peripheral tissues to the lungs for removal.
Furthermore, CA II plays a significant role in various physiological processes, including respiration, acid-base balance, electrolyte transport, calcification of tissues, and production of aqueous humor in the eye. Deficiency or dysfunction of carbonic anhydrase II can lead to various disorders, such as osteopetrosis and renal tubular acidosis.
The inhibition or activation of CA II activity has been a target for drug development, particularly in the treatment of glaucoma, epilepsy, and other conditions where regulation of acid-base balance is critical.
