title: Effects of polyamines on partial reactions of membrane (Na+ + K+)-ATPase.
abstract: Spermine and spermidine inhibit the (Na+ + K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) reaction so that the effect increases as the ionic content due to Na+ and K+ in the reaction is reduced. Several other amines inhibit (Na+ + K+)-ATPase to varying degress and methylglyoxal-bis-(guanylhydrazone) was the most potent inhibitor among those tested. The inhibition by polyamines of the ATPase is uncompetitive with respect to Mg2+ and ATP activation of the reaction. Various naturally occurring polyamines and other amines inhibited Na+ activation of (Na+ + K+)-ATPase as well as Na+-dependent phosphoenzyme formation in an apparently competitive manner with respect to Na+. Likewise, K+-activation of (Na+ + K+)-ATPase as well as K+-p-nitrophenyl phosphatase was inhibited in an apparently competitive manner with respect to K+. Both the cation charge and structure (e.g., aliphatic chain length) may contribute to the inhibitory effects of the amines; however, Na+ sites appear to be more sensitive to cation charge than the aliphatic chain length of the amine, whereas the opposite appears to be true for K+ sites. The results do not indicate a specific effect of polyamines on (Na+ + K+)-ATPase or its partial reactions.
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000037:antagonists & inhibitors; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000201:enzymology; D008274:Magnesium / Q000494:pharmacology; D008935:Mitoguazone / Q000494:pharmacology; D011073:Polyamines / Q000494:pharmacology*; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013095:Spermidine / Q000494:pharmacology; D013096:Spermine / Q000494:pharmacology
chemical_list: D011073:Polyamines; D013096:Spermine; D000255:Adenosine Triphosphate; D012964:Sodium; D009597:4-Nitrophenylphosphatase; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D008935:Mitoguazone; D013095:Spermidine