The effects of pH and citrate on the activity of nicotinamideA-denine dinucleotide-specific isocitrate dehydrogenase from pea mitochondria.
1. The effect of pH on the co-operative activation of the NAD-specific isocitrate dehydrogenase from pea mitochondria by isocitrate is shown. 2. The interlinked effects of pH on the affinity of the NAD-specific isocitrate dehydrogenase for isocitrate and the dependence of the pH optimum on the substrate concentration are presented. 3. A consideration of the conditions of pH and substrate concentration under which citrate activates the NAD-specific isocitrate dehydrogenase demonstrates similarities between the binding of isocitrate and citrate. 4. A comparison of the effects of citrate and pH on the gross structure of the enzyme is investigated by density-gradient centrifugation. 5. The kinetic interpretations of these results are briefly considered. 6. The metabolic significance of these studies is discussed.
D002499:Centrifugation, Density Gradient; D002951:Citrates; D006863:Hydrogen-Ion Concentration; D007521:Isocitrate Dehydrogenase / Q000302:isolation & purification; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D009243:NAD; D011485:Protein Binding
D002951:Citrates; D009243:NAD; D007521:Isocitrate Dehydrogenase