Catalyzes the reversible hydration of carbon dioxide to form bicarbonate. H(+) + hydrogencarbonate = CO2 + H2O Binds 1 zinc ion per subunit. Inhibited by sulfonamides and sulfamates. The best inhibitors are 3-bromosulfanilamide and indisulam. Homotetramer. Was identified as a high-confidence drug target. Belongs to the beta-class carbonic anhydrase family.