Enzymes
| UniProtKB help_outline | 4 proteins |
| Enzyme class help_outline |
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- Name help_outline GDP-β-L-gulose Identifier CHEBI:149550 Charge -2 Formula C16H23N5O16P2 InChIKeyhelp_outline MVMSCBBUIHUTGJ-KTEPSGLNSA-L SMILEShelp_outline N1(C2=C(C(NC(=N2)N)=O)N=C1)C3O[C@H](COP(OP(O[C@H]4O[C@H]([C@@H](O)[C@@H]([C@@H]4O)O)CO)([O-])=O)([O-])=O)[C@H]([C@H]3O)O 2D coordinates Mol file for the small molecule Search links Involved in 2 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline GDP-β-L-galactose Identifier CHEBI:61454 Charge -2 Formula C16H23N5O16P2 InChIKeyhelp_outline MVMSCBBUIHUTGJ-JGQUBWHWSA-L SMILEShelp_outline Nc1nc2n(cnc2c(=O)[nH]1)[C@@H]1O[C@H](COP([O-])(=O)OP([O-])(=O)O[C@H]2O[C@@H](CO)[C@@H](O)[C@@H](O)[C@@H]2O)[C@@H](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 4 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:63804 | RHEA:63805 | RHEA:63806 | RHEA:63807 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Characterization of a GDP-d-mannose 3'',5''-epimerase from rice.
Watanabe K., Suzuki K., Kitamura S.
The enzymatic characterization of GDP-d-mannose 3'',5''-epimerase (GME), a key enzyme in the biosynthesis of vitamin C in plants is described. The GME gene (Genbank Accession No. AB193582) in rice was cloned, and expressed as a fusion protein in Escherichia coli. Reaction products from GDP-d-manno ... >> More
The enzymatic characterization of GDP-d-mannose 3'',5''-epimerase (GME), a key enzyme in the biosynthesis of vitamin C in plants is described. The GME gene (Genbank Accession No. AB193582) in rice was cloned, and expressed as a fusion protein in Escherichia coli. Reaction products from GDP-d-mannose, as produced by GME catalysis, were separated by recycling HPLC on an ODS column, and were determined to be GDP-l-galactose and GDP-l-gulose, based on their NMR spectra and sugar analysis. The reaction catalyzed by GME was inhibited by GDP, and was strongly accelerated by NAD(+) in contrast to the case of GME from Arabidopsis thaliana. This difference in the effect of NAD(+) on GME activity can be attributed to the NAD binding domain which is conserved in the rice gene, but not in the Arabidopsis thaliana gene. The apparent K(m) and k(cat) were determined to be 1.20x10(-5)M and 0.127s(-1), respectively, in the presence of 20microM NAD(+). The fractions of GDP-d-mannose, GDP-l-galactose and GDP-l-gulose, at equilibrium, were approximately 0.75, 0.20 and 0.05, respectively. << Less
Phytochemistry 67:338-346(2006) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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Structure and function of GDP-mannose-3',5'-epimerase: an enzyme which performs three chemical reactions at the same active site.
Major L.L., Wolucka B.A., Naismith J.H.
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 ... >> More
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. << Less
J. Am. Chem. Soc. 127:18309-18320(2005) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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Partial purification and identification of GDP-mannose 3',5'-epimerase of Arabidopsis thaliana, a key enzyme of the plant vitamin C pathway.
Wolucka B.A., Persiau G., Van Doorsselaere J., Davey M.W., Demol H., Vandekerckhove J., Van Montagu M., Zabeau M., Boerjan W.
The first step in the biosynthetic pathway of vitamin C in plants is the formation, at the level of sugar nucleotide, of l-galactosyl residues, catalyzed by a largely unknown GDP-d-mannose 3",5"-epimerase. By using combined conventional biochemical and mass spectrometry methods, we obtained a high ... >> More
The first step in the biosynthetic pathway of vitamin C in plants is the formation, at the level of sugar nucleotide, of l-galactosyl residues, catalyzed by a largely unknown GDP-d-mannose 3",5"-epimerase. By using combined conventional biochemical and mass spectrometry methods, we obtained a highly purified preparation of GDP-d-mannose 3",5"-epimerase from an Arabidopsis thaliana cell suspension. The native enzyme is an 84-kDa dimer, composed of two apparently identical subunits. In-gel tryptic digestion of the enzyme subunit, followed by peptide sequencing and a blast search, led to the identification of the epimerase gene. The closest homolog of the plant epimerase is the BlmG gene product of Streptomyces sp., a putative NDP-d-mannose 5"-epimerase. The plant GDP-d-mannose 3",5"-epimerase is, to our knowledge, a novel member of the extended short-chain dehydrogenase/reductase family. The enzyme was cloned and expressed in Escherichia coli cells. << Less
Proc. Natl. Acad. Sci. U.S.A. 98:14843-14848(2001) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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GDP-D-mannose: GDP-L-galactose epimerase from Chlorella pyrenoidosa.
Barber G.A., Hebda P.A.
Methods Enzymol 83:522-525(1982) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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The guanosine 5'-diphosphate D-mannose: guanosine 5'-diphosphate L-galactose epimerase of Chlorella pyrenoidosa. Chemical synthesis of guanosine 5'-diphosphate L-galactose and further studies of the enzyme and the reaction it catalyzes.
Hebda P.A., Behrman E.J., Barber G.A.
Arch Biochem Biophys 194:496-502(1979) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.