1xik: Difference between revisions
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[[Image:1xik.jpg|left|200px]]<br /><applet load="1xik" size=" | [[Image:1xik.jpg|left|200px]]<br /><applet load="1xik" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1xik, resolution 1.7Å" /> | caption="1xik, resolution 1.7Å" /> | ||
'''RIBONUCLEOSIDE-DIPHOSPHATE REDUCTASE 1 BETA CHAIN'''<br /> | '''RIBONUCLEOSIDE-DIPHOSPHATE REDUCTASE 1 BETA CHAIN'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
1XIK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with FE2 and HG as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ribonucleoside-diphosphate_reductase Ribonucleoside-diphosphate reductase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.17.4.1 1.17.4.1] Known structural/functional Sites: <scene name='pdbsite=FE1:Ferrous Form Of Diiron Cluster In Chain A'>FE1</scene> and <scene name='pdbsite=FE2:Ferrous Form Of Diiron Cluster In Chain B'>FE2</scene>. Full crystallographic information is available from [http:// | 1XIK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=FE2:'>FE2</scene> and <scene name='pdbligand=HG:'>HG</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ribonucleoside-diphosphate_reductase Ribonucleoside-diphosphate reductase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.17.4.1 1.17.4.1] Known structural/functional Sites: <scene name='pdbsite=FE1:Ferrous+Form+Of+Diiron+Cluster+In+Chain+A'>FE1</scene> and <scene name='pdbsite=FE2:Ferrous+Form+Of+Diiron+Cluster+In+Chain+B'>FE2</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XIK OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: oxidoreductase]] | [[Category: oxidoreductase]] | ||
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Revision as of 11:22, 3 February 2008
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RIBONUCLEOSIDE-DIPHOSPHATE REDUCTASE 1 BETA CHAIN
OverviewOverview
BACKGROUND. Ribonucleotide reductases (RNRs) catalyze the formation of the, deoxyribonucleotides that are essential for DNA synthesis. The R2 subunit, of Escherichia coli RNR is a homodimer containing one dinuclear iron, centre per monomer. A tyrosyl radical is essential for catalysis, and is, formed via a reaction in which the reduced, diferrous form of the iron, centre activates dioxygen. To help understand the mechanism of oxygen, activation, we examined the structure of the diferrous form of R2., RESULTS. The crystal structures of reduced forms of both wild type R2 and, a mutant of R2 (Ser211--> Ala) have been determined at 1.7 A and 2.2 A, resolution, respectively. The diferrous iron centre was compared to the, previously determined structure of the oxidized, diferric form of R2. In, both forms of R2 the iron centre is coordinated by the same carboxylate, dominated ligand sphere, but in the reduced form there are clear, conformational changes in three of the carboxylate ligands and the, bridging mu-oxo group and two water molecules are lost. In the reduced, form of R2 the coordination number decreases from six to four for both, ferrous ions, explaining their high reactivity towards dioxygen. The, structure of the mutant Ser211--> Ala, known to have impaired reduction, kinetics, shows a large conformational change in one of the neighbouring, helices although the iron coordination is very similar to the wild type, protein. CONCLUSIONS. Carboxylate shifts are often important for, carboxylate coordinated metal clusters; they allow the metals to achieve, different coordination modes in redox reactions. In the case of reduced R2, these carboxylate shifts allow the formation of accessible reaction sites, for dioxygen. The Ser211--> Ala mutant displays a conformational change in, the helix containing the mutation, explaining its altered reduction, kinetics.
About this StructureAbout this Structure
1XIK is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Ribonucleoside-diphosphate reductase, with EC number 1.17.4.1 Known structural/functional Sites: and . Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of reduced protein R2 of ribonucleotide reductase: the structural basis for oxygen activation at a dinuclear iron site., Logan DT, Su XD, Aberg A, Regnstrom K, Hajdu J, Eklund H, Nordlund P, Structure. 1996 Sep 15;4(9):1053-64. PMID:8805591
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