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[[Image:1ecp.jpg|left|200px]]<br /><applet load="1ecp" size="350" color="white" frame="true" align="right" spinBox="true"
caption="1ecp, resolution 2.0&Aring;" />
'''PURINE NUCLEOSIDE PHOSPHORYLASE'''<br />


==Overview==
==PURINE NUCLEOSIDE PHOSPHORYLASE==
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.
<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 [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12]. 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 [https://proteopedia.org/fgij/fg.htm?mol=1ECP 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&#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=1ecp FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ecp OCA], [https://pdbe.org/1ecp PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1ecp RCSB], [https://www.ebi.ac.uk/pdbsum/1ecp PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1ecp ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/DEOD_ECOLI DEOD_ECOLI] Cleavage of guanosine or inosine to respective bases and sugar-1-phosphate molecules.[HAMAP-Rule:MF_01627]
== 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/main_output.php?pdb_ID=1ecp ConSurf].
<div style="clear:both"></div>


==About this Structure==
==See Also==
1ECP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [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] Known structural/functional Sites: <scene name='pdbsite=S1:Phosphate+Binding+Site'>S1</scene> and <scene name='pdbsite=S2:Base+Binding+Site'>S2</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ECP OCA].
*[[Purine nucleoside phosphorylase 3D structures|Purine nucleoside phosphorylase 3D structures]]
 
__TOC__
==Reference==
</StructureSection>
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:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=9351810 9351810]
[[Category: Escherichia coli K-12]]
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Purine-nucleoside phosphorylase]]
[[Category: Ealick SE]]
[[Category: Single protein]]
[[Category: Mao C]]
[[Category: Ealick, S.E.]]
[[Category: Mao, C.]]
[[Category: glycosyltransferase]]
[[Category: pentosyltransferase]]
[[Category: purine nucleoside phosphorylase]]
 
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Feb  3 09:39:05 2008''

Latest revision as of 10:01, 7 February 2024

PURINE NUCLEOSIDE PHOSPHORYLASEPURINE NUCLEOSIDE PHOSPHORYLASE

Structural highlights

1ecp is a 6 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 2Å
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

DEOD_ECOLI Cleavage of guanosine or inosine to respective bases and sugar-1-phosphate molecules.[HAMAP-Rule:MF_01627]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

See Also

1ecp, resolution 2.00Å

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