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==Crystal stucture of Purine Nucleoside Phosphorylase from Trichomonas vaginalis with Imm-A==
 
<StructureSection load='2i4t' size='340' side='right' caption='[[2i4t]], [[Resolution|resolution]] 2.74&Aring;' scene=''>
==Crystal structure of Purine Nucleoside Phosphorylase from Trichomonas vaginalis with Imm-A==
<StructureSection load='2i4t' size='340' side='right'caption='[[2i4t]], [[Resolution|resolution]] 2.74&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
<table><tr><td colspan='2'>[[2i4t]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Trichomonas_vaginalis Trichomonas vaginalis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2I4T OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2I4T FirstGlance]. <br>
<table><tr><td colspan='2'>[[2i4t]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Trichomonas_vaginalis Trichomonas vaginalis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2I4T OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2I4T FirstGlance]. <br>
</td></tr><tr><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene>, <scene name='pdbligand=UA2:3,4-PYRROLIDINEDIOL,2-(4-AMINO-5H-PYRROLO[3,2-D]PYRIMIDIN-7-YL)-5-(HYDROXYMETHYL)-2S,3S,4R,5R'>UA2</scene><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]] 2.74&#8491;</td></tr>
<tr><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Purine-nucleoside_phosphorylase Purine-nucleoside phosphorylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.2.1 2.4.2.1] </span></td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene>, <scene name='pdbligand=UA2:3,4-PYRROLIDINEDIOL,2-(4-AMINO-5H-PYRROLO[3,2-D]PYRIMIDIN-7-YL)-5-(HYDROXYMETHYL)-2S,3S,4R,5R'>UA2</scene></td></tr>
<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2i4t FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2i4t OCA], [http://www.rcsb.org/pdb/explore.do?structureId=2i4t RCSB], [http://www.ebi.ac.uk/pdbsum/2i4t PDBsum]</span></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=2i4t FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2i4t OCA], [https://pdbe.org/2i4t PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2i4t RCSB], [https://www.ebi.ac.uk/pdbsum/2i4t PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2i4t ProSAT]</span></td></tr>
<table>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A2E7Y6_TRIV3 A2E7Y6_TRIV3]
== Evolutionary Conservation ==
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
Check<jmol>
   <jmolCheckbox>
   <jmolCheckbox>
     <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/i4/2i4t_consurf.spt"</scriptWhenChecked>
     <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/i4/2i4t_consurf.spt"</scriptWhenChecked>
     <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
     <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
     <text>to colour the structure by Evolutionary Conservation</text>
     <text>to colour the structure by Evolutionary Conservation</text>
   </jmolCheckbox>
   </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/chain_selection.php?pdb_ID=2ata ConSurf].
</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=2i4t ConSurf].
<div style="clear:both"></div>
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Trichomonas vaginalis is a parasitic protozoan purine auxotroph possessing a unique purine salvage pathway consisting of a bacterial type purine nucleoside phosphorylase (PNP) and a purine nucleoside kinase. Thus, T. vaginalis PNP (TvPNP) functions in the reverse direction relative to the PNPs in other organisms. Immucillin-A (ImmA) and DADMe-Immucillin-A (DADMe-ImmA) are transition state mimics of adenosine with geometric and electrostatic features that resemble early and late transition states of adenosine at the transition state stabilized by TvPNP. ImmA demonstrates slow-onset tight-binding inhibition with TvPNP, to give an equilibrium dissociation constant of 87 pM, an inhibitor release half-time of 17.2 min, and a Km/Kd ratio of 70,100. DADMe-ImmA resembles a late ribooxacarbenium ion transition state for TvPNP to give a dissociation constant of 30 pM, an inhibitor release half-time of 64 min, and a Km/Kd ratio of 203,300. The tight binding of DADMe-ImmA supports a late SN1 transition state. Despite their tight binding to TvPNP, ImmA and DADMe-ImmA are weak inhibitors of human and P. falciparum PNPs. The crystal structures of the TvPNP x ImmA x PO4 and TvPNP x DADMe-ImmA x PO4 ternary complexes differ from previous structures with substrate analogues. The tight binding with DADMe-ImmA is in part due to a 2.7 A ionic interaction between a PO4 oxygen and the N1' cation of the hydroxypyrrolidine and is weaker in the TvPNP x ImmA x PO4 structure at 3.5 A. However, the TvPNP x ImmA x PO4 structure includes hydrogen bonds between the 2'-hydroxyl and the protein that are not present in TvPNP x DADMe-ImmA x PO4. These structures explain why DADMe-ImmA binds tighter than ImmA. Immucillin-H is a 12 nM inhibitor of TvPNP but a 56 pM inhibitor of human PNP. And this difference is explained by isotope-edited difference infrared spectroscopy with [6-18O]ImmH to establish that O6 is the keto tautomer in TvPNP x ImmH x PO4, causing an unfavorable leaving-group interaction.
Inhibition and structure of Trichomonas vaginalis purine nucleoside phosphorylase with picomolar transition state analogues.,Rinaldo-Matthis A, Wing C, Ghanem M, Deng H, Wu P, Gupta A, Tyler PC, Evans GB, Furneaux RH, Almo SC, Wang CC, Schramm VL Biochemistry. 2007 Jan 23;46(3):659-68. PMID:17223688<ref>PMID:17223688</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>


==See Also==
==See Also==
*[[Purine nucleoside phosphorylase|Purine nucleoside phosphorylase]]
*[[Purine nucleoside phosphorylase 3D structures|Purine nucleoside phosphorylase 3D structures]]
== References ==
<references/>
__TOC__
__TOC__
</StructureSection>
</StructureSection>
[[Category: Purine-nucleoside phosphorylase]]
[[Category: Large Structures]]
[[Category: Trichomonas vaginalis]]
[[Category: Trichomonas vaginalis]]
[[Category: Almo, S C.]]
[[Category: Almo SC]]
[[Category: Rinaldo-Matthis, A.]]
[[Category: Rinaldo-Matthis A]]
[[Category: Schramm, V L.]]
[[Category: Schramm VL]]
[[Category: Purine nucleoside phosphorylase]]
[[Category: Transferase]]

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