| Literature DB >> 7215339 |
Abstract
Two independent methods were used to assess the dependence of the activity of ox brain NAD+-dependent isocitrate dehydrogenase on the concentration of magnesium ions. The results indicated the complex between magnesium and isocitrate to be the true substrate for the enzyme. Free isocitrate is neither a substrate nor an inhibitor of the enzyme but free magnesium ions inhibit competitively with respect to the magnesium-isocitrate complex. The inhibition of the enzyme by ATP and citrate appears to be largely explicable in terms of their effects on the concentration of the complex between Mg2+ and isocitrate. The dependence of the activation of the enzyme by ADP on the concentration of magnesium ions suggests that free ADP, rather than its complex with Mg2+, is the activator.Entities:
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Year: 1981 PMID： 7215339 DOI： 10.1111/j.1432-1033.1981.tb05088.x
Source DB: PubMed Journal: Eur J Biochem ISSN： 0014-2956