Carbonic anhydrase alpha, CA isozyme V_like subgroup. Carbonic anhydrases (CAs) are zinc-containing enzymes that catalyze the reversible hydration of carbon dioxide in a two-step mechanism: a nucleophilic attack of a zinc-bound hydroxide ion on carbon dioxide, followed by the regeneration of the active site by ionization of the zinc-bound water molecule and removal of a proton from the active site. They are ubiquitous enzymes involved in fundamental processes like photosynthesis, respiration, pH homeostasis and ion transport. Most alpha CAs are monomeric enzymes. The zinc ion is complexed by three histidines. This vertebrate subgroup comprises isozyme V. CA V is the mitochondrial isozyme, which may play a role in gluconeogenesis and ureagenesis and possibly also in lipogenesis.