isocitrate dehydrogenase (NADP+) activity

Definition

Target type: molecularfunction

Catalysis of the reaction: isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH. [RHEA:19629]

Isocitrate dehydrogenase (NADP+) is an enzyme that catalyzes the oxidative decarboxylation of isocitrate to α-ketoglutarate, utilizing NADP+ as an electron acceptor. This reaction is a key step in the citric acid cycle, also known as the Krebs cycle, a central metabolic pathway that generates energy in the form of ATP. The enzyme's primary molecular function involves several crucial steps:

1. **Substrate Binding:** Isocitrate dehydrogenase (NADP+) binds to its substrate, isocitrate, and the cofactor NADP+.
2. **Oxidation and Decarboxylation:** The enzyme oxidizes the secondary alcohol group of isocitrate to a ketone group, simultaneously releasing a molecule of carbon dioxide (CO2). This process is facilitated by the enzyme's active site, which contains a metal ion, usually manganese (Mn2+), that assists in the oxidation reaction.
3. **NADP+ Reduction:** The electrons removed from isocitrate are transferred to NADP+, reducing it to NADPH. NADPH is an important reducing agent in various metabolic pathways, including fatty acid biosynthesis and the detoxification of reactive oxygen species.
4. **Product Release:** The enzyme releases the product, α-ketoglutarate, and the reduced cofactor, NADPH.

The isocitrate dehydrogenase (NADP+) activity is essential for the proper functioning of the citric acid cycle, and its deficiency can lead to various metabolic disorders.'
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Proteins (2)

Compounds (12)