Isocitrate dehydrogenase
| Isocitrate dehydrogenase | |||||||||
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Crystallographic structure of E. coli isocitrate dehydrogenase. There are three active sites. Three isocitrates, one isocitrate in the binding site for NADP+.
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| Identifiers | |||||||||
| EC number | 1.1.1.42 | ||||||||
| CAS number | 9028-48-2 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / EGO | ||||||||
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| Search | |
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| PMC | articles |
| PubMed | articles |
| NCBI | proteins |
| isocitrate dehydrogenase (NAD+) | |||||||||
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| Identifiers | |||||||||
| EC number | 1.1.1.41 | ||||||||
| CAS number | 9001-58-5 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / EGO | ||||||||
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| Search | |
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| PMC | articles |
| PubMed | articles |
| NCBI | proteins |
| Monomeric isocitrate dehydrogenase | |||||||||
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crystal structure of the monomeric isocitrate dehydrogenase in complex with isocitrate and mn
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| Identifiers | |||||||||
| Symbol | IDH | ||||||||
| Pfam | PF03971 | ||||||||
| Pfam clan | CL0270 | ||||||||
| InterPro | IPR004436 | ||||||||
| SCOP | 1ofg | ||||||||
| SUPERFAMILY | 1ofg | ||||||||
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| Available protein structures: | |
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| Pfam | structures |
| PDB | RCSB PDB; PDBe; PDBj |
| PDBsum | structure summary |
| isocitrate dehydrogenase 1 (NADP+), soluble | |
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| Identifiers | |
| Symbol | IDH1 |
| Entrez | 3417 |
| HUGO | 5382 |
| OMIM | 147700 |
| RefSeq | NM_005896 |
| UniProt | O75874 |
| Other data | |
| EC number | 1.1.1.42 |
| Locus | Chr. 2 q32-qter |
| isocitrate dehydrogenase 2 (NADP+), mitochondrial | |
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| Identifiers | |
| Symbol | IDH2 |
| Entrez | 3418 |
| HUGO | 5383 |
| OMIM | 147650 |
| RefSeq | NM_002168 |
| UniProt | P48735 |
| Other data | |
| EC number | 1.1.1.42 |
| Locus | Chr. 15 q21-qter |
| isocitrate dehydrogenase 3 (NAD+) alpha | |
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| Identifiers | |
| Symbol | IDH3A |
| Entrez | 3419 |
| HUGO | 5384 |
| OMIM | 601149 |
| RefSeq | NM_005530 |
| UniProt | P50213 |
| Other data | |
| EC number | 1.1.1.41 |
| Locus | Chr. 15 q25.1-25.2 |
| isocitrate dehydrogenase 3 (NAD+) beta | |
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| Identifiers | |
| Symbol | IDH3B |
| Entrez | 3420 |
| HUGO | 5385 |
| OMIM | 604526 |
| RefSeq | NM_174855 |
| UniProt | O43837 |
| Other data | |
| EC number | 1.1.1.41 |
| Locus | Chr. 20 p13 |
Isocitrate dehydrogenase (IDH) (EC 1.1.1.42) and (EC 1.1.1.41) is an enzyme that catalyzes the oxidative decarboxylation of isocitrate, producing alpha-ketoglutarate (α-ketoglutarate) and CO2. This is a two-step process, which involves oxidation of isocitrate (a secondary alcohol) to oxalosuccinate (a ketone), followed by the decarboxylation of the carboxyl group beta to the ketone, forming alpha-ketoglutarate. In humans, IDH exists in three isoforms: IDH3 catalyzes the third step of the citric acid cycle while converting NAD+ to NADH in the . The isoforms IDH1 and IDH2 catalyze the same reaction outside the context of the citric acid cycle and use NADP+ as a cofactor instead of NAD+. They localize to the cytosol as well as the and peroxisome.
The following is a list of human isocitrate dehydrogenase isozymes:
Each NADP+-dependent isozyme functions as a homodimer:
The isocitrate dehydrogenase 3 isozyme is a heterotetramer that is composed of two alpha subunits, one beta subunit, and one gamma subunit:
The NAD-IDH is composed of 3 subunits, is allosterically regulated, and requires an integrated Mg2+ or Mn2+ ion. The closest homologue that has a known structure is the E. coli NADP-dependent IDH, which has only 2 subunits and a 13% identity and 29% similarity based on the amino acid sequences, making it dissimilar to human IDH and not suitable for close comparison. All the known NADP-IDHs are homodimers.
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