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| - | [[Image:1pc4.jpg|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1pc4| PDB=1pc4 | SCENE= }} | | {{STRUCTURE_1pc4| PDB=1pc4 | SCENE= }} |
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| - | '''Crystal Structure of the P50A mutant of ferredoxin I at 1.65 A Resolution'''
| + | ===Crystal Structure of the P50A mutant of ferredoxin I at 1.65 A Resolution=== |
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| - | ==Overview==
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| - | The 7Fe ferredoxin from Azotobacter vinelandii (AvFdI) contains a [3Fe-4S](+/0) cluster that binds a single proton in its reduced level. Although the cluster is buried, and therefore inaccessible to solvent, proton transfer from solvent to the cluster is fast. The kinetics and energetics of the coupled electron-proton transfer reaction at the cluster have been analyzed in detail by protein-film voltammetry, to reveal that proton transfer is mediated by the mobile carboxylate of an adjacent surface residue, aspartate-15, the pK of which is sensitive to the charge on the cluster. This paper examines the role of a nearby proline residue, proline-50, in proton transfer and its coupling to electron transfer. In the P50A and P50G mutants, a water molecule has entered the cluster binding region; it is hydrogen bonded to the backbone amide of residue-50 and to the Asp-15 carboxylate, and it is approximately 4 A from the closest sulfur atom of the cluster. Despite the water molecule linking the cluster more directly to the solvent, proton transfer is not accelerated. A detailed analysis reveals that Asp-15 remains a central part of the mechanism. However, the electrostatic coupling between cluster and carboxylate is almost completely quenched, so that cluster reduction no longer induces such a favorable shift in the carboxylate pK, and protonation of the base no longer induces a significant shift in the pK of the cluster. The electrostatic coupling is crucial for maintaining the efficiency of proton transfer both to and from the cluster, over a range of pH values. | + | The line below this paragraph, {{ABSTRACT_PUBMED_12962482}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 12962482 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_12962482}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Iron-sulfur protein]] | | [[Category: Iron-sulfur protein]] |
| | [[Category: Mutant]] | | [[Category: Mutant]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 04:55:37 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 14:52:53 2008'' |
Revision as of 11:52, 29 July 2008
Template:STRUCTURE 1pc4
Crystal Structure of the P50A mutant of ferredoxin I at 1.65 A Resolution
Template:ABSTRACT PUBMED 12962482
About this Structure
1PC4 is a Single protein structure of sequence from Azotobacter vinelandii. Full crystallographic information is available from OCA.
Reference
Mechanisms of redox-coupled proton transfer in proteins: role of the proximal proline in reactions of the [3Fe-4S] cluster in Azotobacter vinelandii ferredoxin I., Camba R, Jung YS, Hunsicker-Wang LM, Burgess BK, Stout CD, Hirst J, Armstrong FA, Biochemistry. 2003 Sep 16;42(36):10589-99. PMID:12962482
Page seeded by OCA on Tue Jul 29 14:52:53 2008
