2c54

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[[Image:2c54.gif|left|200px]]
[[Image:2c54.gif|left|200px]]
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{{Structure
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<!--
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|PDB= 2c54 |SIZE=350|CAPTION= <scene name='initialview01'>2c54</scene>, resolution 1.500&Aring;
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The line below this paragraph, containing "STRUCTURE_2c54", creates the "Structure Box" on the page.
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|SITE= <scene name='pdbsite=AC1:Epe+Binding+Site+For+Chain+A'>AC1</scene>
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You may change the PDB parameter (which sets the PDB file loaded into the applet)
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|LIGAND= <scene name='pdbligand=EPE:4-(2-HYDROXYETHYL)-1-PIPERAZINE+ETHANESULFONIC+ACID'>EPE</scene>, <scene name='pdbligand=FMT:FORMIC+ACID'>FMT</scene>, <scene name='pdbligand=GKD:GUANOSINE+5&#39;-DIPHOSPHATE-4-KETO-BETA-L-GULOSE'>GKD</scene>, <scene name='pdbligand=GKE:GUANOSINE+5&#39;-DIPHOSPHATE-BETA-L-GULOSE'>GKE</scene>, <scene name='pdbligand=NAD:NICOTINAMIDE-ADENINE-DINUCLEOTIDE'>NAD</scene>
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or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/GDP-mannose_3,5-epimerase GDP-mannose 3,5-epimerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.1.3.18 5.1.3.18] </span>
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or leave the SCENE parameter empty for the default display.
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|GENE=
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-->
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|DOMAIN=
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{{STRUCTURE_2c54| PDB=2c54 | SCENE= }}
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|RELATEDENTRY=
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|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2c54 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2c54 OCA], [http://www.ebi.ac.uk/pdbsum/2c54 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=2c54 RCSB]</span>
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}}
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'''GDP-MANNOSE-3', 5'-EPIMERASE (ARABIDOPSIS THALIANA), K178R, WITH GDP-BETA-L-GULOSE AND GDP-4-KETO-BETA-L-GULOSE BOUND IN ACTIVE SITE.'''
'''GDP-MANNOSE-3', 5'-EPIMERASE (ARABIDOPSIS THALIANA), K178R, WITH GDP-BETA-L-GULOSE AND GDP-4-KETO-BETA-L-GULOSE BOUND IN ACTIVE SITE.'''
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[[Category: Wolucka, B A.]]
[[Category: Wolucka, B A.]]
[[Category: 3' 5'-epimerase]]
[[Category: 3' 5'-epimerase]]
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[[Category: ascorbate biosynthesis]]
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[[Category: Ascorbate biosynthesis]]
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[[Category: gdp-galactose]]
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[[Category: Gdp-galactose]]
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[[Category: gdp-gulose]]
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[[Category: Gdp-gulose]]
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[[Category: gdp-mannose]]
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[[Category: Gdp-mannose]]
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[[Category: isomerase]]
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[[Category: Isomerase]]
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[[Category: keto intermediate]]
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[[Category: Keto intermediate]]
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[[Category: nad]]
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[[Category: Nad]]
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[[Category: sdr]]
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[[Category: Sdr]]
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[[Category: short chain dehydratase/reductase]]
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[[Category: Short chain dehydratase/reductase]]
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[[Category: vitamin c]]
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[[Category: Vitamin c]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 21:15:49 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 02:16:26 2008''
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Revision as of 18:15, 3 May 2008

Image:2c54.gif

Template:STRUCTURE 2c54

GDP-MANNOSE-3', 5'-EPIMERASE (ARABIDOPSIS THALIANA), K178R, WITH GDP-BETA-L-GULOSE AND GDP-4-KETO-BETA-L-GULOSE BOUND IN ACTIVE SITE.


Overview

GDP-mannose-3',5'-epimerase (GME) from Arabidopsis thaliana catalyzes the epimerization of both the 3' and 5' positions of GDP-alpha-D-mannose to yield GDP-beta-L-galactose. Production of the C5' epimer of GDP-alpha-D-mannose, GDP-beta-L-gulose, has also been reported. The reaction occurs as part of vitamin C biosynthesis in plants. We have determined structures of complexes of GME with GDP-alpha-D-mannose, GDP-beta-L-galactose, and a mixture of GDP-beta-L-gulose with GDP-beta-L-4-keto-gulose to resolutions varying from 2.0 to 1.4 A. The enzyme has the classical extended short-chain dehydratase/reductase (SDR) fold. We have confirmed that GME establishes an equilibrium between two products, GDP-beta-L-galactose and GDP-beta-L-gulose. The reaction proceeds by C4' oxidation of GDP-alpha-D-mannose followed by epimerization of the C5' position to give GDP-beta-L-4-keto-gulose. This intermediate is either reduced to give GDP-beta-L-gulose or the C3' position is epimerized to give GDP-beta-L-4-keto-galactose, then C4' is reduced to GDP-beta-L-galactose. The combination of oxidation, epimerization, and reduction in a single active site is unusual. Structural analysis coupled to site-directed mutagenesis suggests C145 and K217 as the acid/base pair responsible for both epimerizations. On the basis of the structure of the GDP-beta-L-gulose/GDP-beta-L-4-keto-gulose co-complex, we predict that a ring flip occurs during the first epimerization and that a boat intermediate is likely for the second epimerization. Comparison of GME with other SDR enzymes known to abstract a protein alpha to the keto function of a carbohydrate identifies key common features.

About this Structure

2C54 is a Single protein structure of sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA.

Reference

Structure and function of GDP-mannose-3',5'-epimerase: an enzyme which performs three chemical reactions at the same active site., Major LL, Wolucka BA, Naismith JH, J Am Chem Soc. 2005 Dec 28;127(51):18309-20. PMID:16366586 Page seeded by OCA on Sat May 3 21:15:49 2008

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