View source for 1ecp

==PURINE NUCLEOSIDE PHOSPHORYLASE==
<StructureSection load='1ecp' size='340' side='right' caption='[[1ecp]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1ecp]] is a 6 chain structure with sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ECP OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ECP FirstGlance]. <br>
</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><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ecp FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ecp OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1ecp RCSB], [http://www.ebi.ac.uk/pdbsum/1ecp PDBsum]</span></td></tr>
<table>
== 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/ec/1ecp_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/chain_selection.php?pdb_ID=2ata ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
BACKGROUND: Purine nucleoside phosphorylase (PNP) from Escherichia coli is a hexameric enzyme that catalyzes the reversible phosphorolysis of 6-amino and 6-oxopurine (2'-deoxy)ribonucleosides to the free base and (2'-deoxy)ribose-1-phosphate. In contrast, human and bovine PNPs are trimeric and accept only 6-oxopurine nucleosides as substrates. The difference in the specificities of these two enzymes has been utilized in gene therapy treatments in which certain prodrugs are cleaved by E. coli PNP but not the human enzyme. The trimeric and hexameric PNPs show no similarity in amino acid sequence, even though they catalyze the same basic chemical reaction. Structural comparison of the active sites of mammalian and E. coli PNPs would provide an improved basis for the design of potential prodrugs that are specific for E. coli PNP. RESULTS: The crystal structure of E. coli PNP at 2.0 A resolution shows that the overall subunit topology and active-site location within the subunit are similar to those of the subunits from human PNP and E. coli uridine phosphorylase. Nevertheless, even though the overall geometry of the E. coli PNP active site is similar to human PNP, the active-site residues and subunit interactions are strikingly different. In E. coli PNP, the purine- and ribose-binding sites are generally hydrophobic, although a histidine residue from an adjacent subunit probably forms a hydrogen bond with a hydroxyl group of the sugar. The phosphate-binding site probably consists of two main-chain nitrogen atoms and three arginine residues. In addition, the active site in hexameric PNP is much more accessible than in trimeric PNP. CONCLUSIONS: The structures of human and E. coli PNP define two possible classes of nucleoside phosphorylase, and help to explain the differences in specificity and efficiency between trimeric and hexameric PNPs. This structural data may be useful in designing prodrugs that can be activated by E. coli PNP but not the human enzyme.

The crystal structure of Escherichia coli purine nucleoside phosphorylase: a comparison with the human enzyme reveals a conserved topology.,Mao C, Cook WJ, Zhou M, Koszalka GW, Krenitsky TA, Ealick SE Structure. 1997 Oct 15;5(10):1373-83. PMID:9351810<ref>PMID:9351810</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>

==See Also==
*[[Purine nucleoside phosphorylase|Purine nucleoside phosphorylase]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Purine-nucleoside phosphorylase]]
[[Category: Ealick, S E.]]
[[Category: Mao, C.]]
[[Category: Glycosyltransferase]]
[[Category: Pentosyltransferase]]
[[Category: Purine nucleoside phosphorylase]]