9icd
From Proteopedia
(New page: 200px<br /><applet load="9icd" size="450" color="white" frame="true" align="right" spinBox="true" caption="9icd, resolution 2.5Å" /> '''CATALYTIC MECHANISM O...) |
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| - | [[Image:9icd.gif|left|200px]]<br /><applet load="9icd" size=" | + | [[Image:9icd.gif|left|200px]]<br /><applet load="9icd" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="9icd, resolution 2.5Å" /> | caption="9icd, resolution 2.5Å" /> | ||
'''CATALYTIC MECHANISM OF NADP+-DEPENDENT ISOCITRATE DEHYDROGENASE: IMPLICATIONS FROM THE STRUCTURES OF MAGNESIUM-ISOCITRATE AND NADP+ COMPLEXES'''<br /> | '''CATALYTIC MECHANISM OF NADP+-DEPENDENT ISOCITRATE DEHYDROGENASE: IMPLICATIONS FROM THE STRUCTURES OF MAGNESIUM-ISOCITRATE AND NADP+ COMPLEXES'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The structures of NADP+ and magnesium isocitrate bound to the | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 9ICD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with NAP as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Isocitrate_dehydrogenase_(NADP(+)) Isocitrate dehydrogenase (NADP(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.42 1.1.1.42] Full crystallographic information is available from [http:// | + | 9ICD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=NAP:'>NAP</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Isocitrate_dehydrogenase_(NADP(+)) Isocitrate dehydrogenase (NADP(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.42 1.1.1.42] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9ICD OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Isocitrate dehydrogenase (NADP(+))]] | [[Category: Isocitrate dehydrogenase (NADP(+))]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Dean, A | + | [[Category: Dean, A M.]] |
| - | [[Category: Hurley, J | + | [[Category: Hurley, J H.]] |
| - | [[Category: Koshlandjunior, D | + | [[Category: Koshlandjunior, D E.]] |
| - | [[Category: Stroud, R | + | [[Category: Stroud, R M.]] |
[[Category: NAP]] | [[Category: NAP]] | ||
[[Category: oxidoreductase (nad(a)-choh(d))]] | [[Category: oxidoreductase (nad(a)-choh(d))]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:18:34 2008'' |
Revision as of 17:18, 21 February 2008
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CATALYTIC MECHANISM OF NADP+-DEPENDENT ISOCITRATE DEHYDROGENASE: IMPLICATIONS FROM THE STRUCTURES OF MAGNESIUM-ISOCITRATE AND NADP+ COMPLEXES
Overview
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.
About this Structure
9ICD is a Single protein structure of sequence from Escherichia coli with as ligand. Active as Isocitrate dehydrogenase (NADP(+)), with EC number 1.1.1.42 Full crystallographic information is available from OCA.
Reference
Catalytic mechanism of NADP(+)-dependent isocitrate dehydrogenase: implications from the structures of magnesium-isocitrate and NADP+ complexes., Hurley JH, Dean AM, Koshland DE Jr, Stroud RM, Biochemistry. 1991 Sep 3;30(35):8671-8. PMID:1888729
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