View source for 1sqc


==SQUALENE-HOPENE-CYCLASE FROM ALICYCLOBACILLUS ACIDOCALDARIUS==
<StructureSection load='1sqc' size='340' side='right' caption='[[1sqc]], [[Resolution|resolution]] 2.85&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1sqc]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Atcc_27009 Atcc 27009]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SQC OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1SQC FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=LDA:LAURYL+DIMETHYLAMINE-N-OXIDE'>LDA</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=1sqc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1sqc OCA], [http://pdbe.org/1sqc PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1sqc RCSB], [http://www.ebi.ac.uk/pdbsum/1sqc PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1sqc ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/SQHC_ALIAD SQHC_ALIAD]] Catalyzes the cyclization of squalene into hopene. 
== 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/sq/1sqc_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/main_output.php?pdb_ID=1sqc ConSurf].
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== Publication Abstract from PubMed ==
The crystal structure of squalene-hopene cyclase from Alicyclobacillus acidocaldarius was determined at 2.9 angstrom resolution. The mechanism and sequence of this cyclase are closely related to those of 2,3-oxidosqualene cyclases that catalyze the cyclization step in cholesterol biosynthesis. The structure reveals a membrane protein with membrane-binding characteristics similar to those of prostaglandin-H2 synthase, the only other reported protein of this type. The active site of the enzyme is located in a large central cavity that is of suitable size to bind squalene in its required conformation and that is lined by aromatic residues. The structure supports a mechanism in which the acid starting the reaction by protonating a carbon-carbon double bond is an aspartate that is coupled to a histidine. Numerous surface alpha helices are connected by characteristic QW-motifs (Q is glutamine and W is tryptophan) that tighten the protein structure, possibly for absorbing the reaction energy without structural damage.

Structure and function of a squalene cyclase.,Wendt KU, Poralla K, Schulz GE Science. 1997 Sep 19;277(5333):1811-5. PMID:9295270<ref>PMID:9295270</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 1sqc" style="background-color:#fffaf0;"></div>

==See Also==
*[[Squalene-hopene cyclase|Squalene-hopene cyclase]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Atcc 27009]]
[[Category: Schulz, G E]]
[[Category: Wendt, K U]]
[[Category: Isomerase]]
[[Category: Membrane protein]]
[[Category: Terpenoid metabolism]]