View source for 2a8z


==Structure Of A Cold-Adapted Family 8 Xylanase==
<StructureSection load='2a8z' size='340' side='right'caption='[[2a8z]], [[Resolution|resolution]] 3.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2a8z]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Pseudoalteromonas_haloplanktis Pseudoalteromonas haloplanktis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2A8Z OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2A8Z 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]] 3.2&#8491;</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=2a8z FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2a8z OCA], [https://pdbe.org/2a8z PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2a8z RCSB], [https://www.ebi.ac.uk/pdbsum/2a8z PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2a8z ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q8RJN8_PSEHA Q8RJN8_PSEHA] 
== 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/a8/2a8z_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=2a8z ConSurf].
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== Publication Abstract from PubMed ==
Site-directed mutagenesis and a comparative characterisation of the kinetic parameters, pH dependency of activity and thermal stability of mutant and wild-type enzymes have been used in association with crystallographic analysis to delineate the functions of several active site residues in a novel glycoside hydrolase family 8 xylanase. Each of the residues investigated plays an essential role in this enzyme: E78 as the general acid, D281 as the general base and in orientating the nucleophilic water molecule, Y203 in maintaining the position of the nucleophilic water molecule and in structural integrity and D144 in sugar ring distortion and transition state stabilization. Interestingly, although crystal structure analyses and the pH-activity profiles clearly identify the functions of E78 and D281, substitution of these residues with their amide derivatives results in only a 250-fold and 700-fold reduction in their apparent k(cat) values, respectively. This, in addition to the observation that the proposed general base is not conserved in all glycoside hydrolase family 8 enzymes, indicates that the mechanistic architecture in this family of inverting enzymes is more complex than is conventionally believed and points to a diversity in the identity of the mechanistically important residues as well as in the arrangement of the intricate microenvironment of the active site among members of this family.

Study of the active site residues of a glycoside hydrolase family 8 xylanase.,Collins T, De Vos D, Hoyoux A, Savvides SN, Gerday C, Van Beeumen J, Feller G J Mol Biol. 2005 Nov 25;354(2):425-35. Epub 2005 Oct 10. PMID:16246370<ref>PMID:16246370</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 2a8z" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Pseudoalteromonas haloplanktis]]
[[Category: Collins T]]
[[Category: De Vos D]]
[[Category: Feller G]]
[[Category: Gerday C]]
[[Category: Hoyoux A]]
[[Category: Savvides SN]]
[[Category: Van Beeumen J]]