Reaction: isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH + H+ (overall reaction)
(1a) isocitrate + NADP+ = oxalosuccinate + NADPH + H+
(1b) oxalosuccinate = 2-oxoglutarate + CO2
For diagram click here or here.
Glossary: isocitrate = (1R,2S)-1-hydroxypropane-1,2,3-tricarboxylate (previously known as threo-DS-isocitrate)
oxalosuccinate = 1-oxopropane-1,2,3-tricarboxylate
Other name(s): oxalosuccinate decarboxylase; isocitrate dehydrogenase (NADP); oxalsuccinic decarboxylase; isocitrate (NADP) dehydrogenase; isocitrate (nicotinamide adenine dinucleotide phosphate) dehydrogenase; NADP-specific isocitrate dehydrogenase; NADP-linked isocitrate dehydrogenase; NADP-dependent isocitrate dehydrogenase; NADP isocitric dehydrogenase; isocitrate dehydrogenase (NADP-dependent); NADP-dependent isocitric dehydrogenase; triphosphopyridine nucleotide-linked isocitrate dehydrogenase-oxalosuccinate carboxylase; NADP+-linked isocitrate dehydrogenase; IDH (ambiguous); dual-cofactor-specific isocitrate dehydrogenase; NADP+-ICDH; NADP+-IDH; IDP; IDP1; IDP2; IDP3
Systematic name: isocitrate:NADP+ oxidoreductase (decarboxylating)
Comments: Requires Mn2+ or Mg2+ for activity. Unlike EC 126.96.36.199, isocitrate dehydrogenase (NAD+), oxalosuccinate can be used as a substrate. In eukaryotes, isocitrate dehydrogenase exists in two forms: an NAD+-linked enzyme found only in mitochondria and displaying allosteric properties, and a non-allosteric, NADP+-linked enzyme that is found in both mitochondria and cytoplasm . The enzyme from some species can also use NAD+ but much more slowly [6,7].
Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9028-48-2
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8. Koh, H.J., Lee, S.M., Son, B.G., Lee, S.H., Ryoo, Z.Y., Chang, K.T., Park, J.W., Park, D.C., Song, B.J., Veech, R.L., Song, H. and Huh, T.L. Cytosolic NADP+-dependent isocitrate dehydrogenase plays a key role in lipid metabolism. J. Biol. Chem. 279 (2004) 39968-39974. [PMID: 15254034]
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