1orr

<table><tr><td colspan='2'>[[1orr]] is a 4 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ORR OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ORR FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CDP:CYTIDINE-5-DIPHOSPHATE'>CDP</scene>, <scene name='pdbligand=NAD:NICOTINAMIDE-ADENINE-DINUCLEOTIDE'>NAD</scene></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1orr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1orr OCA], [http://pdbe.org/1orr PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1orr RCSB], [http://www.ebi.ac.uk/pdbsum/1orr PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1orr ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/RFBE_SALTI RFBE_SALTI]] Catalyzes the isomeration of CDP-paratose to CDP-tyvelose.

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== Publication Abstract from PubMed ==

Tyvelose epimerase catalyzes the last step in the biosynthesis of tyvelose by converting CDP-d-paratose to CDP-d-tyvelose. This unusual 3,6-dideoxyhexose occurs in the O-antigens of some types of Gram-negative bacteria. Here we describe the cloning, protein purification, and high-resolution x-ray crystallographic analysis of tyvelose epimerase from Salmonella typhi complexed with CDP. The enzyme from S. typhi is a homotetramer with each subunit containing 339 amino acid residues and a tightly bound NAD+ cofactor. The quaternary structure of the enzyme displays 222 symmetry and can be aptly described as a dimer of dimers. Each subunit folds into two distinct lobes: the N-terminal motif responsible for NAD+ binding and the C-terminal region that harbors the binding site for CDP. The analysis described here demonstrates that tyvelose epimerase belongs to the short-chain dehydrogenase/reductase superfamily of enzymes. Indeed, its active site is reminiscent to that observed for UDP-galactose 4-epimerase, an enzyme that plays a key role in galactose metabolism. Unlike UDP-galactose 4-epimerase where the conversion of configuration occurs about C-4 of the UDP-glucose or UDP-galactose substrates, in the reaction catalyzed by tyvelose epimerase, the inversion of stereochemistry occurs at C-2. On the basis of the observed binding mode for CDP, it is possible to predict the manner in which the substrate, CDP-paratose, and the product, CDP-tyvelose, might be accommodated within the active site of tyvelose epimerase.

High resolution x-ray structure of tyvelose epimerase from Salmonella typhi.,Koropatkin NM, Liu HW, Holden HM J Biol Chem. 2003 Jun 6;278(23):20874-81. Epub 2003 Mar 17. PMID:12642575<ref>PMID:12642575</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 1orr" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Holden, H M]]

[[Category: Koropatkin, N M]]

[[Category: Liu, H]]

[[Category: Isomerase]]

[[Category: Short-chain dehydrogenase/reductase]]