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New page: left|200px<br /><applet load="2ctx" size="450" color="white" frame="true" align="right" spinBox="true" caption="2ctx, resolution 2.4Å" /> '''THE REFINED CRYSTAL S...
 
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[[Image:2ctx.jpg|left|200px]]<br /><applet load="2ctx" size="450" color="white" frame="true" align="right" spinBox="true"
caption="2ctx, resolution 2.4&Aring;" />
'''THE REFINED CRYSTAL STRUCTURE OF ALPHA-COBRATOXIN FROM NAJA NAJA SIAMENSIS AT 2.4-ANGSTROMS RESOLUTION'''<br />


==Overview==
==THE REFINED CRYSTAL STRUCTURE OF ALPHA-COBRATOXIN FROM NAJA NAJA SIAMENSIS AT 2.4-ANGSTROMS RESOLUTION==
The crystal structure of the "long" alpha-neurotoxin alpha-cobratoxin was, refined to an R-factor of 19.5% using 3271 x-ray data to 2.4-A resolution., The polypeptide chain forms three loops, I, II, III, knotted together by, four disulfide bridges, with the most prominent, loop II, containing, another disulfide close to its lower tip. Loop I is stabilized by one, beta-turn and two beta-sheet hydrogen bonds; loop II by eight beta-sheet, hydrogen bonds, with the tip folded into two distorted right-handed, helical turns stabilized by two alpha-helical and two beta-turn hydrogen, bonds; and loop III by hydrophobic interactions and one beta-turn. Loop II, and one strand of loop III form an antiparallel triple-pleated beta-sheet, and tight anchoring of the Asn63 side chain fixes the tail segment. In the, crystal lattice, the alpha-cobratoxin molecules dimerize by beta-sheet, formation between strands 53 and 57 of symmetry-related molecules. Because, such interactions are found also in a cardiotoxin and alpha-bungarotoxin, this could be of importance for interaction with acetylcholine receptor.
<StructureSection load='2ctx' size='340' side='right'caption='[[2ctx]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2ctx]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Naja_naja Naja naja]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2CTX OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2CTX 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]] 2.4&#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=2ctx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ctx OCA], [https://pdbe.org/2ctx PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2ctx RCSB], [https://www.ebi.ac.uk/pdbsum/2ctx PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2ctx ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/3L23_NAJNA 3L23_NAJNA] Binds with high affinity to muscular (alpha-1/CHRNA1) and neuronal (alpha-7/CHRNA7) nicotinic acetylcholine receptor (nAChR) and inhibits acetylcholine from binding to the receptor, thereby impairing neuromuscular and neuronal transmission.[UniProtKB:P60615]
== 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/ct/2ctx_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=2ctx ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The crystal structure of the "long" alpha-neurotoxin alpha-cobratoxin was refined to an R-factor of 19.5% using 3271 x-ray data to 2.4-A resolution. The polypeptide chain forms three loops, I, II, III, knotted together by four disulfide bridges, with the most prominent, loop II, containing another disulfide close to its lower tip. Loop I is stabilized by one beta-turn and two beta-sheet hydrogen bonds; loop II by eight beta-sheet hydrogen bonds, with the tip folded into two distorted right-handed helical turns stabilized by two alpha-helical and two beta-turn hydrogen bonds; and loop III by hydrophobic interactions and one beta-turn. Loop II and one strand of loop III form an antiparallel triple-pleated beta-sheet, and tight anchoring of the Asn63 side chain fixes the tail segment. In the crystal lattice, the alpha-cobratoxin molecules dimerize by beta-sheet formation between strands 53 and 57 of symmetry-related molecules. Because such interactions are found also in a cardiotoxin and alpha-bungarotoxin, this could be of importance for interaction with acetylcholine receptor.


==About this Structure==
The refined crystal structure of alpha-cobratoxin from Naja naja siamensis at 2.4-A resolution.,Betzel C, Lange G, Pal GP, Wilson KS, Maelicke A, Saenger W J Biol Chem. 1991 Nov 15;266(32):21530-6. PMID:1939183<ref>PMID:1939183</ref>
2CTX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Naja_naja Naja naja]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2CTX OCA].


==Reference==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
The refined crystal structure of alpha-cobratoxin from Naja naja siamensis at 2.4-A resolution., Betzel C, Lange G, Pal GP, Wilson KS, Maelicke A, Saenger W, J Biol Chem. 1991 Nov 15;266(32):21530-6. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=1939183 1939183]
</div>
<div class="pdbe-citations 2ctx" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Naja naja]]
[[Category: Naja naja]]
[[Category: Single protein]]
[[Category: Betzel C]]
[[Category: Betzel, C.]]
[[Category: Lange G]]
[[Category: Lange, G.]]
[[Category: Maelicke A]]
[[Category: Maelicke, A.]]
[[Category: Pal GP]]
[[Category: Pal, G.P.]]
[[Category: Saenger W]]
[[Category: Saenger, W.]]
[[Category: Wilson KS]]
[[Category: Wilson, K.S.]]
[[Category: neurotoxin]]
 
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Retrieved from "https://proteopedia.org/2ctx"