Effect of Divalent Metal Ions on Nucleotide Inhibition of Pig Heart Citrate Synthase

The effect of divalent metal ions on the reaction catalyzed by pig heart citrate synthase has been investigated. Concentrations of divalent metal ions (Mn ++ , Mg ++ , and Ca ++ ) in 100-fold excess of acetyl coenzyme A concentration inhibit the enzymic reaction. It is suggested that the inhibition...

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Veröffentlicht in:The Journal of biological chemistry 1966-08, Vol.241 (15), p.3571-3574
Hauptverfasser: Kosicki, G W, Lee, L P
Format: Artikel
Sprache:eng
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Zusammenfassung:The effect of divalent metal ions on the reaction catalyzed by pig heart citrate synthase has been investigated. Concentrations of divalent metal ions (Mn ++ , Mg ++ , and Ca ++ ) in 100-fold excess of acetyl coenzyme A concentration inhibit the enzymic reaction. It is suggested that the inhibition is due to chelate formation between the divalent metal ions and the acetyl-CoA molecule, most likely at the polyphosphate chain of the molecule. The inhibition of pig heart citrate synthase by adenosine triphosphate and other nucleotides, palmitoyl-CoA, reduced nicotinamide adenine dinucleotide, and reduced nicotinamide adenine dinucleotide phosphate was studied. Divalent metal ions (Mn ++ , Mg ++ , and Ca ++ ) at low concentrations reduce the inhibition. We suggest that the effect is due to the chelation of the metal ions with the polyphosphate moiety of the inhibitor molecules.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)99868-6