1rpx
From Proteopedia
(New page: 200px<br /><applet load="1rpx" size="450" color="white" frame="true" align="right" spinBox="true" caption="1rpx, resolution 2.30Å" /> '''D-RIBULOSE-5-PHOSPHA...) |
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| - | [[Image:1rpx.gif|left|200px]]<br /><applet load="1rpx" size=" | + | [[Image:1rpx.gif|left|200px]]<br /><applet load="1rpx" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1rpx, resolution 2.30Å" /> | caption="1rpx, resolution 2.30Å" /> | ||
'''D-RIBULOSE-5-PHOSPHATE 3-EPIMERASE FROM SOLANUM TUBEROSUM CHLOROPLASTS'''<br /> | '''D-RIBULOSE-5-PHOSPHATE 3-EPIMERASE FROM SOLANUM TUBEROSUM CHLOROPLASTS'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Ribulose-5-phosphate 3-epimerase (EC 5.1.3.1) catalyzes the | + | Ribulose-5-phosphate 3-epimerase (EC 5.1.3.1) catalyzes the interconversion of ribulose-5-phosphate and xylulose-5-phosphate in the Calvin cycle and in the oxidative pentose phosphate pathway. The enzyme from potato chloroplasts was expressed in Escherichia coli, isolated and crystallized. The crystal structure was elucidated by multiple isomorphous replacement and refined at 2.3 A resolution. The enzyme is a homohexamer with D3 symmetry. The subunit chain fold is a (beta alpha)8-barrel. A sequence comparison with homologous epimerases outlined the active center and indicated that all members of this family are likely to share the same catalytic mechanism. The substrate could be modeled by putting its phosphate onto the observed sulfate position and its epimerized C3 atom between two carboxylates that participate in an extensive hydrogen bonding system. A mutation confirmed the crucial role of one of these carboxylates. The geometry together with the conservation pattern suggests that the negative charge of the putative cis-ene-diolate intermediate is stabilized by the transient induced dipoles of a methionine sulfur "cushion", which is proton-free and therefore prevents isomerization instead of epimerization. |
==About this Structure== | ==About this Structure== | ||
| - | 1RPX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Solanum_tuberosum Solanum tuberosum] with SO4 as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Ribulose-phosphate_3-epimerase Ribulose-phosphate 3-epimerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.1.3.1 5.1.3.1] Full crystallographic information is available from [http:// | + | 1RPX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Solanum_tuberosum Solanum tuberosum] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Ribulose-phosphate_3-epimerase Ribulose-phosphate 3-epimerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.1.3.1 5.1.3.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1RPX OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Solanum tuberosum]] | [[Category: Solanum tuberosum]] | ||
[[Category: Kopp, J.]] | [[Category: Kopp, J.]] | ||
| - | [[Category: Schulz, G | + | [[Category: Schulz, G E.]] |
[[Category: SO4]] | [[Category: SO4]] | ||
[[Category: 3-epimerase]] | [[Category: 3-epimerase]] | ||
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[[Category: oxidative pentose phosphate pathway]] | [[Category: oxidative pentose phosphate pathway]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:53:21 2008'' |
Revision as of 12:53, 21 February 2008
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D-RIBULOSE-5-PHOSPHATE 3-EPIMERASE FROM SOLANUM TUBEROSUM CHLOROPLASTS
Overview
Ribulose-5-phosphate 3-epimerase (EC 5.1.3.1) catalyzes the interconversion of ribulose-5-phosphate and xylulose-5-phosphate in the Calvin cycle and in the oxidative pentose phosphate pathway. The enzyme from potato chloroplasts was expressed in Escherichia coli, isolated and crystallized. The crystal structure was elucidated by multiple isomorphous replacement and refined at 2.3 A resolution. The enzyme is a homohexamer with D3 symmetry. The subunit chain fold is a (beta alpha)8-barrel. A sequence comparison with homologous epimerases outlined the active center and indicated that all members of this family are likely to share the same catalytic mechanism. The substrate could be modeled by putting its phosphate onto the observed sulfate position and its epimerized C3 atom between two carboxylates that participate in an extensive hydrogen bonding system. A mutation confirmed the crucial role of one of these carboxylates. The geometry together with the conservation pattern suggests that the negative charge of the putative cis-ene-diolate intermediate is stabilized by the transient induced dipoles of a methionine sulfur "cushion", which is proton-free and therefore prevents isomerization instead of epimerization.
About this Structure
1RPX is a Single protein structure of sequence from Solanum tuberosum with as ligand. Active as Ribulose-phosphate 3-epimerase, with EC number 5.1.3.1 Full crystallographic information is available from OCA.
Reference
Structure and mechanism of the amphibolic enzyme D-ribulose-5-phosphate 3-epimerase from potato chloroplasts., Kopp J, Kopriva S, Suss KH, Schulz GE, J Mol Biol. 1999 Apr 9;287(4):761-71. PMID:10191144
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