title: Cl- -HCO3- dependent ATPase in gills of freshwater and seawater adapted eels (Anguilla anguilla L.).
abstract: The gills of both seawater and freshwater adapted eels have an ATPase activity which is stimulated by anions in the presence of Mg2+. Plasma membranes were distinguished from mitochondrial membranes with specific enzyme markers, the membrane fractions separated on a discontinuous sucrose gradient, and the ATPase activity of the plasma membranes studied. Activation by the anions of Cl- or HCO3- followed Michaelis-Menten kinetics and was competitively inhibited by SCN-. The Cl- and HCO3- activation characteristics were determined: no differences between the plasma membrane ATPase activities of freshwater and seawater-adapted fishes were observed. Maximal activity measurements after solubilization of the enzymes by Triton X 100 confirmed these findings. The function of a membrane anion-dependent ATPase in the brachial epithelium of euryhaline fish is discussed.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000811:Anguilla / Q000378:metabolism*; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D002712:Chlorides / Q000494:pharmacology; D003576:Electron Transport Complex IV / Q000378:metabolism; D005618:Fresh Water; D005880:Gills / Q000201:enzymology*; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology; D012623:Seawater; D013861:Thiocyanates / Q000494:pharmacology
chemical_list: D001639:Bicarbonates; D002712:Chlorides; D013861:Thiocyanates; D003576:Electron Transport Complex IV; D000251:Adenosine Triphosphatases