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| [[Image:2bhb.jpg|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_2bhb| PDB=2bhb | SCENE= }} | | {{STRUCTURE_2bhb| PDB=2bhb | SCENE= }} |
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| '''ZN SUBSTITUTED E. COLI AMINOPEPTIDASE P'''
| | ===ZN SUBSTITUTED E. COLI AMINOPEPTIDASE P=== |
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| ==Overview==
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| The effect of metal substitution on the activity and structure of the aminopeptidase P (APPro) from Escherichia coli has been investigated. Measurements of activity in the presence of Mn2+, Mg2+, Zn2+, Na+, and Ca2+ show that significant activity is seen only in the Mn-bound form of the enzyme. The addition of Zn2+ to [MnMn(APPro)] is strongly inhibitory. Crystal structures of [MnMn(APPro)], [MgMg(APPro)], [ZnZn(APPro)], [ZnMg(APPro)], [Ca_(APPro)], [Na_(APPro)], and [apo(APPro)] were determined. The structures of [Ca_(APPro)] and [Na_(APPro)] have a single metal atom at their active site. Surprisingly, when a tripeptide substrate (ValProLeu) was soaked into [Na_(APPro)] crystals in the presence of 200 mM Mg2+, the structure had substrate, but no metal, bound at the active site. The structure of apo APPro complexed with ValProLeu shows that the N-terminal amino group of a substrate can be bound at the active site by carboxylate side chains that normally bind the second metal atom, providing a model for substrate binding in a single-metal active enzyme. Structures of [MnMn(APPro)] and [ZnZn(APPro)] complexes of ProLeu, a product inhibitor, in the presence of excess Zn reveal a third metal-binding site, formed by two conserved His residues and the dipeptide inhibitor. A Zn atom bound at such a site would stabilize product binding and enhance inhibition. | | The line below this paragraph, {{ABSTRACT_PUBMED_16229471}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16229471 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16229471}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Pita-bread fold]] | | [[Category: Pita-bread fold]] |
| [[Category: Proline-specific peptidase]] | | [[Category: Proline-specific peptidase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 20:17:10 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 09:41:24 2008'' |
