View source for 2nqd


==Crystal structure of cysteine protease inhibitor, chagasin, in complex with human cathepsin L==
<StructureSection load='2nqd' size='340' side='right'caption='[[2nqd]], [[Resolution|resolution]] 1.75&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2nqd]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Trypanosoma_cruzi Trypanosoma cruzi]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2NQD OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2NQD 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]] 1.75&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</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=2nqd FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2nqd OCA], [https://pdbe.org/2nqd PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2nqd RCSB], [https://www.ebi.ac.uk/pdbsum/2nqd PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2nqd ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CHAG_TRYCR CHAG_TRYCR] 
== 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/nq/2nqd_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=2nqd ConSurf].
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== Publication Abstract from PubMed ==
Chagasin is a protein produced by Trypanosoma cruzi, the parasite that causes Chagas' disease. This small protein belongs to a recently defined family of cysteine protease inhibitors. Although resembling well-known inhibitors like the cystatins in size (110 amino acid residues) and function (they all inhibit papain-like (C1 family) proteases), it has a unique amino acid sequence and structure. We have crystallized and solved the structure of chagasin in complex with the host cysteine protease, cathepsin L, at 1.75 A resolution. An inhibitory wedge composed of three loops (L2, L4, and L6) forms a number of contacts responsible for high-affinity binding (K(i), 39 pM) to the enzyme. All three loops interact with the catalytic groove, with the central loop L2 inserted directly into the catalytic center. Loops L4 and L6 embrace the enzyme molecule from both sides and exhibit distinctly different patterns of protein-protein recognition. Comparison with a 1.7 A structure of uncomplexed chagasin, also determined in this study, demonstrates that a conformational change of the first binding loop (L4) allows extended binding to the non-primed substrate pockets of the enzyme active site cleft, thereby providing a substantial part of the inhibitory surface. The mode of chagasin binding is generally similar, albeit distinctly different in detail, when compared to those displayed by cystatins and the cysteine protease inhibitory p41 fragment of the invariant chain. The chagasin-cathepsin L complex structure provides details of how the parasite protein inhibits a host enzyme of possible importance in host defense. The high level of structural and functional similarity between cathepsin L and the T. cruzi enzyme cruzipain gives clues to how the cysteine protease activity of the parasite can be targeted. This information will aid in the development of synthetic inhibitors for use as potential drugs for the treatment of Chagas disease.

Crystal structure of the parasite protease inhibitor chagasin in complex with a host target cysteine protease.,Ljunggren A, Redzynia I, Alvarez-Fernandez M, Abrahamson M, Mort JS, Krupa JC, Jaskolski M, Bujacz G J Mol Biol. 2007 Aug 3;371(1):137-53. Epub 2007 May 10. PMID:17561110<ref>PMID:17561110</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 2nqd" style="background-color:#fffaf0;"></div>

==See Also==
*[[Cathepsin 3D structures|Cathepsin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Trypanosoma cruzi]]
[[Category: Abrahamson M]]
[[Category: Bujacz G]]
[[Category: Jaskolski M]]
[[Category: Ljunggren A]]
[[Category: Redzynia I]]