Carbonic anhydrase (carbonate dehydratase) is a family of metalloenzymes (enzymes that contain one or more metal atoms as a functional component of the enzyme) that catalyze the rapid interconversion of carbon dioxide and water into carbonic acid, protons, and bicarbonate ions. This reaction occurs spontaneously in aqueous solution, but does so slowly.Badger MR, Price GD. 1994. The role of carbonic anhydrase in photosynthesis.