4.2.1.1	CO2 + H2O	-	
4.2.1.1	CO2 + H2O	periplasmic alpha-carbonic anhydrase activity of Helicobacter pylori is essential for acid acclimation	
4.2.1.1	H2CO3	-	
4.2.1.1	H2CO3	essential physiological function is to catalyze the hydration of carbon dioxide and the backreaction, the dehydration of bicarbonate	
4.2.1.1	H2CO3	plays a role in the hypersensitive defense response	
4.2.1.1	H2CO3	plays a role in various physiological functions, including interconversion between CO2 and HCO3- in intermediary metabolism, facilitated diffusion of CO2, pH homeostasis and ion transport	
4.2.1.1	H2CO3	CsoSCA converts HCO3- to CO2 for use in carbon fixation by ribulose-bisphosphate carboxylase/oxygenase	
4.2.1.1	additional information	carbonic anhydrase I, II and III are constitutive enzymes	
4.2.1.1	additional information	carbonic anhydrase 2 is induced by high CO2 concentration, carbonic anhydrase 1 is induced by low and high CO2 concentration	
4.2.1.1	additional information	carbonic anhydrase IV is possibly responsible for HCO3- secretion, the cytoplasmic form of carbonic anhydrase II is believed to play a role in pH regulation near apical ionic channels of the near apical carbonic anhydrase IV