Kinetic studies on inhibition of dog heart Na+,K+-dependent ATPase by K+,Mg2+-aspartate: comparison with ouabain.
Both K+,Mg+-dependent D,L-aspartate and D,L-aspartic acid are noncompetitive inhibitors of dog heart Na+,K+-ATPase acting at the overlapping site as does ouabain. For the Na+,K+-ATPase, the salient effects of K+,Mg+-D,L-aspartate and/or D,L-asartic acid were: 1) decrease in maximal velocity (V) for ATP as substrate with unchanged Km; 2) for sodium as an allosteric modifier of Na+,K+-ATPase activity, a decrease in V without any alteration in n as measure of cooperativity between activating sites; 3) for potassium, a decrease in V and n as well as an increase in K0.5 values. Thus, for enzyme activity in the presence of sodium and ATP, a high affinity to potassium was reduced by D,L-aspartic acid.
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009206:Myocardium / Q000201:enzymology*; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000037:antagonists & inhibitors / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology
D001224:Aspartic Acid; D010042:Ouabain; D012964:Sodium; D000251:Adenosine Triphosphatases; D008274:Magnesium; D011188:Potassium