1sk0

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{{Seed}}
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{{STRUCTURE_1sk0| PDB=1sk0 | SCENE= }}
{{STRUCTURE_1sk0| PDB=1sk0 | SCENE= }}
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'''ARSENATE REDUCTASE R60A MUTANT +0.4M ARSENITE FROM E. COLI'''
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===ARSENATE REDUCTASE R60A MUTANT +0.4M ARSENITE FROM E. COLI===
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==Overview==
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Arsenic is a ubiquitous environmental toxic metal. Consequently, organisms detoxify arsenate by reduction to arsenite, which is then excreted or sequestered. The ArsC arsenate reductase from Escherichia coli plasmid R773, the best characterized arsenic-modifying enzyme, has a catalytic cysteine, Cys 12, in the active site, surrounded by an arginine triad composed of Arg 60, Arg 94, and Arg 107. During the reaction cycle, the native enzyme forms a unique monohydroxyl Cys 12-thiol-arsenite adduct that contains a positive charge on the arsenic. We hypothesized previously that this unstable intermediate allows for rapid dissociation of the product arsenite. In this study, the role of Arg 60 in product formation was evaluated by mutagenesis. A total of eight new structures of ArsC were determined at resolutions between 1.3 A and 1.8 A, with R(free) values between 0.18 and 0.25. The crystal structures of R60K and R60A ArsC equilibrated with the product arsenite revealed a covalently bound Cys 12-thiol-dihydroxyarsenite without a charge on the arsenic atom. We propose that this intermediate is more stable than the monohydroxyarsenite intermediate of the native enzyme, resulting in slow release of product and, consequently, loss of activity.
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(as it appears on PubMed at http://www.pubmed.gov), where 15295115 is the PubMed ID number.
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{{ABSTRACT_PUBMED_15295115}}
==About this Structure==
==About this Structure==
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[[Category: Arsenite]]
[[Category: Arsenite]]
[[Category: Reductase]]
[[Category: Reductase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 08:48:06 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 09:04:39 2008''

Revision as of 06:04, 28 July 2008

Image:1sk0.png

Template:STRUCTURE 1sk0

ARSENATE REDUCTASE R60A MUTANT +0.4M ARSENITE FROM E. COLI

Template:ABSTRACT PUBMED 15295115

About this Structure

1SK0 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Arginine 60 in the ArsC arsenate reductase of E. coli plasmid R773 determines the chemical nature of the bound As(III) product., DeMel S, Shi J, Martin P, Rosen BP, Edwards BF, Protein Sci. 2004 Sep;13(9):2330-40. Epub 2004 Aug 4. PMID:15295115

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