Nicotinamide adenine dinucleotide phosphate linked isocitrate dehydrogenase. Catalytic activation by the reduced coenzyme product of the reaction.
The oxidative decarboxylation of D-isocitrate catalyzed by NADP-linked isocitrate dehydrogenase is activated by NADPH, the product of the reaction. We analyzed the autocatalytic behavior exhibited by the enzyme during the steady-state kinetics. NADP acts as a competitive inhibitor toward NADPH in the catalytic activation. In a large concentration range of the reduced and oxidized coenzymes, the activity of the enzyme is proportional to the ratio (NADPH)/(NADP). The results are compared with the results of experiments done with other NADP-linked decarboxylating dehydrogenases. Two different models are presented in order to explain the mechanism of action of isocitrate dehydrogenase, according to our data.
D001665:Binding Sites; D004789:Enzyme Activation / Q000187:drug effects; D007521:Isocitrate Dehydrogenase / Q000378:metabolism*; D007700:Kinetics; D008024:Ligands; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008433:Mathematics; D009249:NADP / Q000494:pharmacology*; D010084:Oxidation-Reduction; D011485:Protein Binding
D008024:Ligands; D008345:Manganese; D009249:NADP; D007521:Isocitrate Dehydrogenase; D008274:Magnesium