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| [[Image:9icd.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_9icd| PDB=9icd | SCENE= }} | | {{STRUCTURE_9icd| PDB=9icd | SCENE= }} |
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| '''CATALYTIC MECHANISM OF NADP+-DEPENDENT ISOCITRATE DEHYDROGENASE: IMPLICATIONS FROM THE STRUCTURES OF MAGNESIUM-ISOCITRATE AND NADP+ COMPLEXES'''
| | ===CATALYTIC MECHANISM OF NADP+-DEPENDENT ISOCITRATE DEHYDROGENASE: IMPLICATIONS FROM THE STRUCTURES OF MAGNESIUM-ISOCITRATE AND NADP+ COMPLEXES=== |
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| ==Overview==
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| The structures of NADP+ and magnesium isocitrate bound to the NADP(+)-dependent isocitrate dehydrogenase of Escherichia coli have been determined and refined at 2.5-A resolution. NADP+ is bound by the large domain of isocitrate dehydrogenase, a structure that has little similarity to the supersecondary structure of the nucleotide-binding domain of the lactate dehydrogenase-like family of nucleotide-binding proteins. The coenzyme-binding site confirms the fundamentally different evolution of the isocitrate dehydrogenase-like and the lactate dehydrogenase-like classes of nucleotide-binding proteins. In the magnesium-isocitrate complex, magnesium is coordinated to the alpha-carboxylate and alpha-hydroxyl oxygen of isocitrate in a manner suitable for stabilization of a negative charge on the hydroxyl oxygen during both the dehydrogenation and decarboxylation steps of the conversion of isocitrate to alpha-ketoglutarate. The metal ion is also coordinated by aspartate side chains 283' (of the second subunit of the dimer) and 307 and two water molecules in a roughly octahedral arrangement. On the basis of the geometry of the active site, the base functioning in the dehydrogenation step is most likely aspartate 283'. E. coli isocitrate dehydrogenase transfers a hydride stereospecifically to the A-side of NADP+, and models for a reactive ternary complex consistent with this stereospecificity are discussed. | | The line below this paragraph, {{ABSTRACT_PUBMED_1888729}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 1888729 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_1888729}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Koshlandjunior, D E.]] | | [[Category: Koshlandjunior, D E.]] |
| [[Category: Stroud, R M.]] | | [[Category: Stroud, R M.]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 22:53:16 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Jul 11 12:50:00 2008'' |
