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| | {{STRUCTURE_1nit| PDB=1nit | SCENE= }} | | {{STRUCTURE_1nit| PDB=1nit | SCENE= }} |
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| - | '''CRYSTAL STRUCTURE OF ACONITASE WITH TRANS-ACONITATE AND NITROCITRATE BOUND'''
| + | ===CRYSTAL STRUCTURE OF ACONITASE WITH TRANS-ACONITATE AND NITROCITRATE BOUND=== |
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| - | ==Overview==
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| - | Crystal structures of mitochondrial aconitase with the inhibitors trans-aconitate and nitrocitrate bound to the [4Fe-4S] cluster have been solved and refined at 2.05 A resolution with R-factors of 0.168 and 0.172, respectively. Crystallization of aconitase with the substrates citrate and cis-aconitate has not been possible because the enzyme turns over and selects enzyme with isocitrate bound into the crystal lattice. Therefore we have analyzed crystal structures of the enzyme complexed with inhibitor analogs of these two substrates. The structure with nitrocitrate bound provides a model for citrate binding. The structure with trans-aconitate bound provides a model for cis-aconitate binding in two ways: Fe4 of the [4Fe-4S] cluster is five-coordinate and the carbon at the C beta position is trigonal. These results allow the model for the reaction mechanism to be extended to all three natural substrates of aconitase. The results support a model in which citrate and isocitrate form similar chelate structures related by 180 degrees rotation about the C alpha-C beta bond while the intermediate cis-aconitate binds in either of two ways (citrate mode or isocitrate mode). In both inhibitor complexes a H2O molecule is also bound to Fe4. In the structure with nitrocitrate bound, partial occupancy of sulfate in the active site is observed accompanied by hydroxyl binding to Fe4. Comparison of the structures with isocitrate, trans-aconitate, nitrocitrate and sulfate bound reveals preferred orientations for the three types of oxygens ligated to Fe4 (carboxyl, hydroxyl and H2O) supporting the proposed roles for His101, Asp165 and His167 in the catalytic mechanism.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_8151704}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 8151704 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_8151704}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Lauble, H.]] | | [[Category: Lauble, H.]] |
| | [[Category: Stout, C D.]] | | [[Category: Stout, C D.]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 02:35:06 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 11:24:32 2008'' |
Revision as of 08:24, 29 July 2008
Template:STRUCTURE 1nit
CRYSTAL STRUCTURE OF ACONITASE WITH TRANS-ACONITATE AND NITROCITRATE BOUND
Template:ABSTRACT PUBMED 8151704
About this Structure
1NIT is a Single protein structure of sequence from Bos taurus. Full crystallographic information is available from OCA.
Reference
Crystal structures of aconitase with trans-aconitate and nitrocitrate bound., Lauble H, Kennedy MC, Beinert H, Stout CD, J Mol Biol. 1994 Apr 8;237(4):437-51. PMID:8151704
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