Kinetic effects of ATP, divalent metal ions and pH on chicken liver mevalonate 5-diphosphate decarboxylase.
The activity of chicken liver mevalonate 5-diphosphate decarboxylase was measured over a wide range of Mg2+ and ATP concentrations. It was found that free ATP activated the enzyme, whereas free Mg2+ had no effect on the enzyme activity. Computed analyses of free species concentrations and pH studies indicated that MgATP2- is the true substrate. The relative efficiencies of Mg2+, Mn2+, Cd2+, and Zn2+ as activating metal ions were evaluated in terms of V/Km for the corresponding (metal-ATP)2- complexes, and the relative ratios were: Mn2+ 100, Cd2+ 37, Mg2+ 14, Zn2+ 1.7. Inhibitory effects were demonstrated for all free divalent cations tested, except for Mg2+, and were in the order Zn2+ greater than Cd2+ greater than Mn2+.
Jabalquinto
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AM
Departamento de Química, Facultad de Ciencia, Universidad de Santiago de Chile.
Cardemil
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E
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002262:Carboxy-Lyases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002413:Cations, Divalent; D002645:Chickens; D004789:Enzyme Activation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
D002413:Cations, Divalent; D002104:Cadmium; D008345:Manganese; D000255:Adenosine Triphosphate; D002262:Carboxy-Lyases; C022503:pyrophosphomevalonate decarboxylase; D008274:Magnesium; D015032:Zinc