Carbonic Anhydrase 5B (CA5B) is a member of alpha-carbonic anhydrase family (CAs) that catalyze the reversible hydration of carbon dioxide. CAs is associated with many biological processes; including calcification; respiration; bone resorption; acid-base balance and the formation of aqueous humor. CA5B is highly expressed in heart; pancreas; kidney; placenta; lung; and skeletal muscle; but it is restricted to the liver. CA5B is localized in the mitochondria and shows the highest sequence similarity to the other mitochondrial CA; CA-VA. CA5B is inhibited by coumarins; sulfonamide derivatives such as acetazolamide (AZA); saccharin; and Foscarnet.