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2aqo

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[[Image:2aqo.gif|left|200px]]
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{{Seed}}
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[[Image:2aqo.png|left|200px]]
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{{STRUCTURE_2aqo| PDB=2aqo | SCENE= }}
{{STRUCTURE_2aqo| PDB=2aqo | SCENE= }}
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'''Crystal structure of E. coli Isoaspartyl Dipeptidase Mutant E77Q'''
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===Crystal structure of E. coli Isoaspartyl Dipeptidase Mutant E77Q===
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==Overview==
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Isoaspartyl dipeptidase (IAD) is a binuclear metalloenzyme and a member of the amidohydrolase superfamily. This enzyme catalyzes the hydrolytic cleavage of beta-aspartyl dipeptides. The pH-rate profiles for the hydrolysis of beta-Asp-Leu indicates that catalysis is dependent on the ionization of two groups; one that ionizes at a pH approximately 6 and the other approximately 9. The group that must be ionized for catalysis is directly dependent on the identity of the metal ion bound to the active site. This result is consistent with the ionization of the hydroxide that bridges the two divalent cations. In addition to the residues that interact directly with the divalent cations there are two other residues that are highly conserved and found within the active site: Glu-77 and Tyr-137. Mutation of Tyr-137 to phenylalanine reduced the rate of catalysis by three orders of magnitude. The three dimensional X-ray structure of the Y137F mutant did not show any significant conformation changes relative to the three dimensional structure of the wild-type enzyme. The positioning of the side-chain phenolic group of Tyr-137 in the active site of IAD is consistent with the stabilization of the tetrahedral adduct concomitant with nucleophilic attack by the hydroxide that bridges the two divalent cations. Mutation of Glu-77 resulted in the reduction of catalytic activity by five orders of magnitude. The three dimensional structure of the E77Q mutant did not show any significant conformational changes in the mutant relative to the three dimensional structure of the wild-type enzyme. The positioning of the side-chain carboxylate of Glu-77 is consistent with the formation of an ion pair interaction with the free alpha-amino group of the substrate.
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The line below this paragraph, {{ABSTRACT_PUBMED_16289685}}, adds the Publication Abstract to the page
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(as it appears on PubMed at http://www.pubmed.gov), where 16289685 is the PubMed ID number.
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{{ABSTRACT_PUBMED_16289685}}
==About this Structure==
==About this Structure==
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[[Category: Dipeptidase]]
[[Category: Dipeptidase]]
[[Category: Metallo-protease]]
[[Category: Metallo-protease]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 19:21:22 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 15:40:02 2008''

Revision as of 12:40, 27 July 2008

Image:2aqo.png

Template:STRUCTURE 2aqo

Crystal structure of E. coli Isoaspartyl Dipeptidase Mutant E77Q

Template:ABSTRACT PUBMED 16289685

About this Structure

2AQO is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Functional significance of Glu-77 and Tyr-137 within the active site of isoaspartyl dipeptidase., Marti-Arbona R, Thoden JB, Holden HM, Raushel FM, Bioorg Chem. 2005 Dec;33(6):448-58. Epub 2005 Nov 11. PMID:16289685

Page seeded by OCA on Sun Jul 27 15:40:02 2008

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