title: Comparative properties of mammalian and insect carbonic anhydrases: effects of potassium and chloride on the rate of carbon dioxide hydration.
abstract: 1. Carbonic anhydrase (E.C.4.2.1.1) catalysed CO2 hydration was studied with enzymes from mammalian and insect sources at CO2 concentrations of 7.6-30.8 mM. 2. At 0.01-0.15 M, potassium chloride (KCl) or choline chloride (ChCl) markedly inhibited all 8 mammalian enzymes studied. 3. Inhibition by KCl is always greater than that associated with ChCl. 4. KCl non-competitively inhibits and choline chloride competitively inhibits bovine carbonic anhydrase. 5. Carbonic anhydrase obtained from fat body, integumentary epithelium and midgut tissues of larval tobacco hornworms, Manduca sexta, is greatly stimulated by KCl and slightly inhibited by ChCl. 6. We propose that the effect of K+ on mammalian and insect carbonic anhydrases if fundamentally different.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002245:Carbon Dioxide / Q000378:metabolism*; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology*; D002256:Carbonic Anhydrases / Q000378:metabolism*; D002417:Cattle; D002794:Choline / Q000494:pharmacology*; D004285:Dogs; D005216:Fat Body / Q000201:enzymology; D006801:Humans; D007700:Kinetics; D007814:Larva / Q000201:enzymology; D007915:Lepidoptera / Q000201:enzymology*; D009036:Moths / Q000201:enzymology*; D011189:Potassium Chloride / Q000494:pharmacology*; D011817:Rabbits
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D002245:Carbon Dioxide; D011189:Potassium Chloride; D002256:Carbonic Anhydrases; D002794:Choline