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.