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| {{STRUCTURE_2g3f| PDB=2g3f | SCENE= }} | | {{STRUCTURE_2g3f| PDB=2g3f | SCENE= }} |
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| '''Crystal Structure of imidazolonepropionase complexed with imidazole-4-acetic acid sodium salt, a substrate homologue'''
| | ===Crystal Structure of imidazolonepropionase complexed with imidazole-4-acetic acid sodium salt, a substrate homologue=== |
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| ==Overview==
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| Imidazolonepropionase (EC 3.5.2.7) catalyzes the third step in the universal histidine degradation pathway, hydrolyzing the carbon-nitrogen bonds in 4-imidazolone-5-propionic acid to yield N-formimino-l-glutamic acid. Here we report the crystal structures of the Bacillus subtilis imidazolonepropionase and its complex at 2.0-A resolution with substrate analog imidazole-4-acetic acid sodium (I4AA). The structure of the native enzyme contains two domains, a TIM (triose-phosphate isomerase) barrel domain with two insertions and a small beta-sandwich domain. The TIM barrel domain is quite similar to the members of the alpha/beta barrel metallo-dependent hydrolase superfamily, especially to Escherichia coli cytosine deaminase. A metal ion was found in the central cavity of the TIM barrel and was tightly coordinated to residues His-80, His-82, His-249, Asp-324, and a water molecule. X-ray fluorescence scan analysis confirmed that the bound metal ion was a zinc ion. An acetate ion, 6 A away from the zinc ion, was also found in the potential active site. In the complex structure with I4AA, a substrate analog, I4AA replaced the acetate ion and contacted with Arg-89, Try-102, Tyr-152, His-185, and Glu-252, further defining and confirming the active site. The detailed structural studies allowed us to propose a zinc-activated nucleophilic attack mechanism for the hydrolysis reaction catalyzed by the enzyme.
| | The line below this paragraph, {{ABSTRACT_PUBMED_16990261}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16990261 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16990261}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| [[Category: Tim barrel]] | | [[Category: Tim barrel]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jun 18 12:15:01 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 00:12:14 2008'' |
