title: Vanadate inhibition of brain (Ca + Mg)-ATPase.
abstract: Vanadate was a potent inhibitor of the membrane-bound (Ca + Mg)-ATPase from rat brain, the concentration required for 50% inhibition under conditions optimal for enzymatic activity being 3 mu M. Vanadate inhibition increased with the MgCl2 concentration, half-maximal inhibition occurring at 2 mM MgCl2, near the MgCl2 concentration required for half-maximal activation of the ATPase activity. MnCl2 could substitute for MgCl2, and at concentrations of 1 mM (Ca + Mn)-ATPase activity was greater than (Ca + Mg)-ATPase activity, although sensitivity to vanadate was less. Vanadate inhibition increased also with the KCl concentration, half-maximal inhibition occurring at 8 mM, again near the concentration required for half-maximal activation of ATPase activity. By contrast, NaCl stimulated (Ca + Mg)-ATPase activity without potentiating vanadate inhibition. These effects of cations on ATPase activity and vanadate inhibition resemble properties of certain transport ATPases and thus suggest mechanistic and functional similarities.
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002712:Chlorides; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride; D008345:Manganese / Q000494:pharmacology; D017895:Manganese Compounds; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D012965:Sodium Chloride / Q000494:pharmacology; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology*
chemical_list: D002712:Chlorides; D017895:Manganese Compounds; D014639:Vanadium; D015636:Magnesium Chloride; D014638:Vanadates; D008345:Manganese; D012965:Sodium Chloride; D011189:Potassium Chloride; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D008274:Magnesium; C025340:manganese chloride