title: Palytoxin isolated from marine coelenterates. The inhibitory action on (Na,K)-ATPase.
abstract: Palytoxin (PTX), C129H223N3O54, a highly toxic substance isolated from zoanthids of Palythoa tuberculosa, inhibited (Na,K)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) prepared from guinea pig heart and hog cerebral cortex in a dose-dependent manner at concentrations greater than 10(-8) M. In the presence of Na (100 mM) and K (20 mM), PTX showed potency nearly equal to that of ouabain. When the ATPase was activated by the various Na concentrations at a constant K concentration, both PTX and ouabain inhibited the ATPase activity noncompetitively. On the other hand, when K concentration was changed at a constant Na concentration, PTX caused a competitive inhibition in all ranges of K concentrations employed, whereas ouabain caused a competitive inhibition at low concentrations and a noncompetitive inhibition at high concentrations.
mesh_terms: D000178:Acrylamides; D000818:Animals; D002540:Cerebral Cortex / Q000201:enzymology*; D003064:Cnidarian Venoms / Q000302:isolation & purification / Q000494:pharmacology*; D006168:Guinea Pigs; D007700:Kinetics; D009206:Myocardium / Q000201:enzymology*; D010042:Ouabain / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013552:Swine; D000095702:Polyether Toxins
chemical_list: D000178:Acrylamides; D003064:Cnidarian Venoms; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; C010272:palytoxin; D000095702:Polyether Toxins