View source for 1qmg

==ACETOHYDROXYACID ISOMEROREDUCTASE COMPLEXED WITH ITS REACTION PRODUCT DIHYDROXY-METHYLVALERATE, MANGANESE AND ADP-RIBOSE.==
<StructureSection load='1qmg' size='340' side='right' caption='[[1qmg]], [[Resolution|resolution]] 1.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1qmg]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Spiol Spiol]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QMG OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1QMG FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=APX:2-MONOPHOSPHOADENOSINE-5-DIPHOSPHORIBOSE'>APX</scene>, <scene name='pdbligand=DMV:2,3-DIHYDROXY-VALERIANIC+ACID'>DMV</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1yve|1yve]]</td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Ketol-acid_reductoisomerase Ketol-acid reductoisomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.86 1.1.1.86] </span></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=1qmg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qmg OCA], [http://pdbe.org/1qmg PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1qmg RCSB], [http://www.ebi.ac.uk/pdbsum/1qmg PDBsum]</span></td></tr>
</table>
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/qm/1qmg_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf].
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== Publication Abstract from PubMed ==
Acetohydroxyacid isomeroreductase catalyses a two-step reaction composed of an alkyl migration followed by an NADPH-dependent reduction. Both steps require a divalent cation and the first step has a strong preference for magnesium. Manganese ions are highly unfavourable to the reaction: only 3% residual activity is observed in the presence of this cation. Acetohydroxyacid isomeroreductase has been crystallized with its substrate, 2-aceto-2-hydroxybutyrate (AHB), Mn(2+) and NADPH. The 1.6 A resolution electron-density map showed the reaction product (2,3-dihydroxy-3-methylvalerate, DHMV) and a density corresponding to (phospho)-ADP-ribose instead of the whole NADP(+). This is one of the few structures of an enzyme complexed with its reaction product. The structure of this complex was refined to an R factor of 19.3% and an R(free) of 22.5%. The overall structure of the enzyme is very similar to that of the complex with the reaction-intermediate analogue IpOHA [N-hydroxy-N-isopropyloxamate; Biou et al. (1997), EMBO J. 16, 3405-3415]. However, the active site shows some differences: the nicotinamide is cleaved and the surrounding amino acids have rearranged accordingly. Comparison between the structures corresponding to the reaction intermediate and to the end of the reaction allowed the proposal of a reaction scheme. Taking this result into account, the enzyme was crystallized with Ni(2+) and Zn(2+), for which only 0.02% residual activity were measured; however, the crystals of AHB/Zn/NADPH and of AHB/Ni/NADPH also contain the reaction product. Moreover, mass-spectrometry measurements confirmed the -cleavage of nicotinamide.

Structure of spinach acetohydroxyacid isomeroreductase complexed with its reaction product dihydroxymethylvalerate, manganese and (phospho)-ADP-ribose.,Thomazeau K, Dumas R, Halgand F, Forest E, Douce R, Biou V Acta Crystallogr D Biol Crystallogr. 2000 Apr;56(Pt 4):389-97. PMID:10739911<ref>PMID:10739911</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 1qmg" style="background-color:#fffaf0;"></div>

==See Also==
*[[Ketol-acid reductoisomerase|Ketol-acid reductoisomerase]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Ketol-acid reductoisomerase]]
[[Category: Spiol]]
[[Category: Biou, V]]
[[Category: Douce, R]]
[[Category: Dumas, R]]
[[Category: Halgand, F]]
[[Category: Thomazeau, K]]
[[Category: Adp-ribose]]
[[Category: Branched chain amino acid biosynthesis]]
[[Category: Manganese]]
[[Category: Oxidoreductase]]
[[Category: Reaction product]]