title: Temperature effects on cation affinities of the (Na+, K+)-ATPase of mammalian brain.
abstract: Effects of temperature on the Na+-dependent ADP-ATP exchange and the p-nitrophenylphosphatase reactions catalysed by (Na+, K+)-ATPase were examined. Apparent Mg2+ affinity decreased with decreasing temperature. Arrhenius plots of p-nitrophenylphosphatase in the presence of Na+ and ATP had discontinuities similar to those previously reported for (Na+ + K+)-ATPase, while those of p-nitrophenylphosphatase measured without Na+ or ATP did not. The apparent activation energy for p-nitrophenylphosphatase was a function of the physical characteristics of the cation acting at the K+ site.
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D010744:Phosphoric Monoester Hydrolases; D009597:4-Nitrophenylphosphatase; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D011188:Potassium