Carbonic Anhydrase

Literature References: Mol wt ~30,000. A small zinc-contg enzyme which catalyzes the hydration of CO2. Found in higher concns in erythrocytes, renal cortex, and gastric mucosa of mammals; also found in other animal tissues, in plants and in some bacteria. Isoln from bovine erythrocytes: Lindskog, Biochim. Biophys. Acta 39, 218 (1960); from human erythrocytes: Nyman, ibid. 52, 1 (1961); from renal cortex: Höber, Proc. Soc. Exp. Biol. Med. 49, 87 (1942); from gastric mucosa: Davenport, Physiol. Rev. 26, 560 (1946). Human carbonic anhydrase consists of two isoenzymes with distinctly different amino acid sequences and specific activities. The high activity form is called carbonic anhydrase C; the low activity form is called B; modified forms of these two isoenzymes exist: Funakoshi, Deutsch, J. Biol. Chem. 243, 6474 (1968); 244, 3438 (1969). Amino acid sequence of carbonic anhydrase B: Anderson et al., Biochem. Biophys. Res. Commun. 48, 670 (1972); Lin, Deutsch, J. Biol. Chem. 248, 1885 (1973); sequence of carbonic anhydrase C: Henderson, Henriksson, Biochem. Biophys. Res. Commun. 52, 1388 (1973); Lin, Deutsch, J. Biol. Chem. 249, 2329 (1974). Crystal structure of carbonic anhydrase C: Liljas et al., Nature New Biol. 235, 131 (1972). Catalyzes the reversible reaction of CO2 and H2O to HCO3- and H+. Permits CO interchange between blood and tissues. In gastric mucosa, reaction rate is sufficient to neutralize the excess alkalinity produced by the ionization of water and secretion of hydrogen ions: Roughton, Clark in The Enzymes vol. 1, part 2, J. B. Sumner, K. Myrbäck, Eds. (Academic Press, New York, 1951) pp 1250-1265. In the kidney, participates in Na+ transport. Review of physiology: Maren in Oxygen Affinity of Hemoglobin and Red Cell Acid Base Status, Alfred Benzon Symposium IV, P. Astrup, M. Roerth, Eds. (Academic Press, New York, 1972) pp 418-433. Review of metal ion function: Prince, Woolley, Angew. Chem. Int. Ed. 11, 408-417 (1972). Review: Lindskog et al., "Carbonic Anhydrase" in The Enzymes vol. 5, P. D. Boyer, Ed. (Academic Press, New York, 1971) pp 587-665.