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[[Image:1pp2.gif|left|200px]]
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{{STRUCTURE_1pp2|  PDB=1pp2  |  SCENE=  }}
'''THE REFINED CRYSTAL STRUCTURE OF DIMERIC PHOSPHOLIPASE A2 AT 2.5 ANGSTROMS. ACCESS TO A SHIELDED CATALYTIC CENTER'''


==THE REFINED CRYSTAL STRUCTURE OF DIMERIC PHOSPHOLIPASE A2 AT 2.5 ANGSTROMS. ACCESS TO A SHIELDED CATALYTIC CENTER==
<StructureSection load='1pp2' size='340' side='right'caption='[[1pp2]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1pp2]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Crotalus_atrox Crotalus atrox]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PP2 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1PP2 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]] 2.5&#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=1pp2 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1pp2 OCA], [https://pdbe.org/1pp2 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1pp2 RCSB], [https://www.ebi.ac.uk/pdbsum/1pp2 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1pp2 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/PA2A_CROAT PA2A_CROAT] PLA2 catalyzes the calcium-dependent hydrolysis of the 2-acyl groups in 3-sn-phosphoglycerides.
== 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/pp/1pp2_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=1pp2 ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The 2.5-A crystal structure of the calcium-free form of the dimeric venom phospholipase A2 from the Western Diamondback rattlesnake Crotalus atrox, has been refined to an R-factor of 17.8% (I greater than 2 sigma) and acceptable stereochemistry. The molecule is a nearly perfect 2-fold symmetric dimer in which most of the catalytic residues of both subunits face an internal cavity. The restricted access to the putative catalytic sites is especially puzzling as the optimal substrates for this and most other phospholipase A2 are phospholipids condensed in micellar or lamellar aggregates. We point out that substrate access to the internal cavity may be aided by calcium binding which can alter the intersubunit contacts that shield the catalytic network. We also suggest that a system of hydrogen-bonded moieties exists on the surface of the dimer that links the amino terminus to the catalytic system, through an invariant Gln 4 side chain and the backbone of the active center residue, Tyr 73. This hydrogen-bonded network is on a highly accessible surface of the dimer and would appear to contribute to the enzyme's (as opposed to the proenzyme's) special capacity to attack aggregated rather than monomeric substrate.


==Overview==
The refined crystal structure of dimeric phospholipase A2 at 2.5 A. Access to a shielded catalytic center.,Brunie S, Bolin J, Gewirth D, Sigler PB J Biol Chem. 1985 Aug 15;260(17):9742-9. PMID:4019493<ref>PMID:4019493</ref>
The 2.5-A crystal structure of the calcium-free form of the dimeric venom phospholipase A2 from the Western Diamondback rattlesnake Crotalus atrox, has been refined to an R-factor of 17.8% (I greater than 2 sigma) and acceptable stereochemistry. The molecule is a nearly perfect 2-fold symmetric dimer in which most of the catalytic residues of both subunits face an internal cavity. The restricted access to the putative catalytic sites is especially puzzling as the optimal substrates for this and most other phospholipase A2 are phospholipids condensed in micellar or lamellar aggregates. We point out that substrate access to the internal cavity may be aided by calcium binding which can alter the intersubunit contacts that shield the catalytic network. We also suggest that a system of hydrogen-bonded moieties exists on the surface of the dimer that links the amino terminus to the catalytic system, through an invariant Gln 4 side chain and the backbone of the active center residue, Tyr 73. This hydrogen-bonded network is on a highly accessible surface of the dimer and would appear to contribute to the enzyme's (as opposed to the proenzyme's) special capacity to attack aggregated rather than monomeric substrate.


==About this Structure==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
1PP2 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Crotalus_atrox Crotalus atrox]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PP2 OCA].
</div>
<div class="pdbe-citations 1pp2" style="background-color:#fffaf0;"></div>


==Reference==
==See Also==
The refined crystal structure of dimeric phospholipase A2 at 2.5 A. Access to a shielded catalytic center., Brunie S, Bolin J, Gewirth D, Sigler PB, J Biol Chem. 1985 Aug 15;260(17):9742-9. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/4019493 4019493]
*[[Phospholipase A2 3D structures|Phospholipase A2 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Crotalus atrox]]
[[Category: Crotalus atrox]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Brunie, S.]]
[[Category: Brunie S]]
[[Category: Sigler, P B.]]
[[Category: Sigler PB]]
[[Category: Hydrolase]]
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