View source for 1fh8


==CRYSTAL STRUCTURE OF THE XYLANASE CEX WITH XYLOBIOSE-DERIVED ISOFAGOMINE INHIBITOR==
<StructureSection load='1fh8' size='340' side='right'caption='[[1fh8]], [[Resolution|resolution]] 1.95&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1fh8]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Cellulomonas_fimi Cellulomonas fimi]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FH8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1FH8 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.95&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=XIF:PIPERIDINE-3,4-DIOL'>XIF</scene>, <scene name='pdbligand=XYP:BETA-D-XYLOPYRANOSE'>XYP</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1fh8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1fh8 OCA], [https://pdbe.org/1fh8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1fh8 RCSB], [https://www.ebi.ac.uk/pdbsum/1fh8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1fh8 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/GUX_CELFI GUX_CELFI] Hydrolyzes both cellulose and xylan. Has also weak endoglucanase activity.  The biological conversion of cellulose to glucose generally requires three types of hydrolytic enzymes: (1) Endoglucanases which cut internal beta-1,4-glucosidic bonds; (2) Exocellobiohydrolases that cut the dissaccharide cellobiose from the non-reducing end of the cellulose polymer chain; (3) Beta-1,4-glucosidases which hydrolyze the cellobiose and other short cello-oligosaccharides to glucose.
== 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/fh/1fh8_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.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/main_output.php?pdb_ID=1fh8 ConSurf].
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== Publication Abstract from PubMed ==
Detailed insights into the mode of binding of a series of tight-binding aza-sugar glycosidase inhibitors of two fundamentally different classes are described through X-ray crystallographic studies of complexes with the retaining family 10 xylanase Cex from Cellulomonas fimi. Complexes with xylobiose-derived aza-sugar inhibitors of the substituted "amidine" class (xylobio-imidazole, K(i) = 150 nM; xylobio-lactam oxime, K(i) = 370 nM) reveal lateral interaction of the "glycosidic" nitrogen with the acid/base catalyst (Glu127) and hydrogen bonding of the sugar 2-hydroxyl with the catalytic nucleophile (Glu233), as expected. Tight binding of xylobio-isofagomine (K(i) = 130 nM) appears to be a consequence of strong interactions of the ring nitrogen with the catalytic nucleophile while, surprisingly, no direct protein contacts are made with the ring nitrogen of the xylobio-deoxynojirimycin analogue (K(i) = 5800 nM). Instead the nitrogen interacts with two ordered water molecules, thereby accounting for its relatively weaker binding, though it still binds some 1200-fold more tightly than does xylobiose, presumably as a consequence of electrostatic interactions at the active site. Dramatically weaker binding of these same inhibitors to the family 11 xylanase Bcx from Bacillus circulans (K(i) from 0.5 to 1.5 mM) is rationalized for the substituted amidines on the basis that this enzyme utilizes a syn protonation trajectory and likely hydrolyzes via a (2,5)B boat transition state. Weaker binding of the deoxynojirimycin and isofagomine analogues likely reflects the energetic penalty for distortion of these analogues to a (2,5)B conformation, possibly coupled with destabilizing interactions with Tyr69, a conserved, catalytically essential active site residue.

Detailed structural analysis of glycosidase/inhibitor interactions: complexes of Cex from Cellulomonas fimi with xylobiose-derived aza-sugars.,Notenboom V, Williams SJ, Hoos R, Withers SG, Rose DR Biochemistry. 2000 Sep 26;39(38):11553-63. PMID:10995222<ref>PMID:10995222</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Cellulomonas fimi]]
[[Category: Large Structures]]
[[Category: Hoos R]]
[[Category: Notenboom V]]
[[Category: Rose DR]]
[[Category: Williams SJ]]
[[Category: Withers SG]]