title: Effects of certain mono-, di- and trivalent metal cations on the K+-stimulated p-Nitrophenyl phosphatase in rat brain.
abstract: The effects of certain monovalent (Ag+1 and Li+1), divalent (Hg+2, Cu+2, Zn+2, Co+2, Fe+2, Pb+2, Mn+2, Sn+2, Ni+2, and Se+2) and trivalent (Fe+3, As+3, and Al+3) metals on a mitochondrial preparation of K+-stimulated-p-nitrophenyl phosphatase (K+-PNPPase) from rat brain were studied. Except for salts of Ni+2, Se+2 and Li+1, which irrespective of concentration failed to produce 50% inhibition, all of the metals examined were found to be potent inhibitors of the enzyme with 150 values of 0.24 microM for Ag+1 among the monovalent, 0.70, 30, 37, 38, 47, 60, 62, 490 and 850 microM for Hg+2, Cu+2, Cd+2, Zn+2, Co+2, Fe+2, Pb+2, Mn+2 and Sn+2, respectively, among the divalents and 100, 550 and 870 microM for Fe+3, As+3, and AL+3 respectively, among the trivalents. Salts of silver and mercury were the most toxic for this enzyme. All metals showed concentration dependent inhibition except lithium. The order of their potency was Ag+1 greater than Hg+2 greater than Cu+2 greater than Cd+2 greater than Zn+2 greater than Co+2 greater than Fe+2 greater than Pb+2 greater than Fe+3 greater than Mn+2 greater than As+3 greater than Sn+2 greater than Al+3 greater than Ni+2 greater than Se+2 greater than Li+1.
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000037:antagonists & inhibitors*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002412:Cations / Q000494:pharmacology*; D008928:Mitochondria / Q000201:enzymology*; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors*; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
chemical_list: D002412:Cations; D010744:Phosphoric Monoester Hydrolases; D009597:4-Nitrophenylphosphatase; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium