View source for 1qws


==Structure of the D181N variant of catalase HPII from E. coli==
<StructureSection load='1qws' size='340' side='right'caption='[[1qws]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1qws]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QWS OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1QWS 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]] 1.9&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</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=1qws FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qws OCA], [https://pdbe.org/1qws PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1qws RCSB], [https://www.ebi.ac.uk/pdbsum/1qws PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1qws ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CATE_ECOLI CATE_ECOLI] Decomposes hydrogen peroxide into water and oxygen; serves to protect cells from the toxic effects of hydrogen peroxide.
== 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/qw/1qws_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=1qws ConSurf].
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== Publication Abstract from PubMed ==
Substrate H2O2 must gain access to the deeply buried active site of catalases through channels of 30-50 A in length. The most prominent or main channel approaches the active site perpendicular to the plane of the heme and contains a number of residues that are conserved in all catalases. Changes in Val169, 8 A from the heme in catalase HPII from Escherichia coli, introducing smaller, larger or polar side chains reduces the catalase activity. Changes in Asp181, 12 A from the heme, reduces activity by up to 90% if the negatively charged side chain is removed when Ala, Gln, Ser, Asn, or Ile are the substituted residues. Only the D181E variant retains wild type activity. Determination of the crystal structures of the Glu181, Ala181, Ser181, and Gln181 variants of HPII reveals lower water occupancy in the main channel of the less active variants, particularly at the position forming the sixth ligand to the heme iron and in the hydrophobic, constricted region adjacent to Val169. It is proposed that an electrical potential exists between the negatively charged aspartate (or glutamate) side chain at position 181 and the positively charged heme iron 12 A distant. The potential field acts upon the electrical dipoles of water generating a common orientation that favors hydrogen bond formation and promotes interaction with the heme iron. Substrate hydrogen peroxide would be affected similarly and would enter the active site oriented optimally for interaction with active site residues.

An electrical potential in the access channel of catalases enhances catalysis.,Chelikani P, Carpena X, Fita I, Loewen PC J Biol Chem. 2003 Aug 15;278(33):31290-6. Epub 2003 May 29. PMID:12777389<ref>PMID:12777389</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Catalase 3D structures|Catalase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Carpena X]]
[[Category: Chelikani P]]
[[Category: Fita I]]
[[Category: Loewen PC]]