Regulation of the F-ATPase from mitochondria of Vigna sinensis (L.) Savi cv. Pitiuba by spermine, spermidine, putrescine, Mg2+, Na+, and K+.
Mitochondria from Vigna sinensis (L.) Savi cv. Pitiuba contain the polyamines spermine, spermidine, and putrescine. The membrane-bound F1-ATPase from mitochondria of Vigna sinensis is activated by these polyamines at physiological concentrations. The effect of polyamines on the membrane-bound of F1-ATPase is dependent on the concentrations of Na+, K+, MgATP, and Mg2+. Excess Na+ or K+ prevents the activation of the membrane-bound F1-ATPase by spermine and spermidine, but not by putrescine. The most pronounced effects were observed at low MgATP concentrations in the absence of Na+ and K+. At [MgATP] = 0.08 mM, spermine activation of the membrane-bound F1-ATPase was 130%. The membrane-bound F1-ATPase is slightly activated by Mg2+ at lower concentrations and strongly inhibited by Mg2+ at higher concentrations. Activation as well as inhibition is dependent on the substrate MgATP concentration. Although there is competition between Mg2+ and MgATP, the binding sites for these two ligands are different (pseudocompetitive inhibition). The inhibition of the membrane-bound F1-ATPase can be reversed by polyamines. There is evidence that the binding sites for Mg2+ and polyamines are identical. The F1-ATPase detached from the membrane is neither activated by polyamines nor inhibited by Mg2+. Therefore, the binding sites for Mg2+ and polyamines seem to be localized on the membrane.
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007887:Fabaceae / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008928:Mitochondria / Q000201:enzymology*; D010946:Plants, Medicinal; D011073:Polyamines / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D006180:Proton-Translocating ATPases; D012964:Sodium / Q000494:pharmacology
D011073:Polyamines; D012964:Sodium; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases; D008274:Magnesium; D011188:Potassium