1yqu

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[[Image:1yqu.gif|left|200px]]
[[Image:1yqu.gif|left|200px]]
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{{Structure
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<!--
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|PDB= 1yqu |SIZE=350|CAPTION= <scene name='initialview01'>1yqu</scene>, resolution 3.1&Aring;
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The line below this paragraph, containing "STRUCTURE_1yqu", creates the "Structure Box" on the page.
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|SITE=
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You may change the PDB parameter (which sets the PDB file loaded into the applet)
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|LIGAND= <scene name='pdbligand=GUN:GUANINE'>GUN</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene>
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or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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|ACTIVITY=
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or leave the SCENE parameter empty for the default display.
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|GENE= xapA, pndA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])
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-->
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|DOMAIN=
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{{STRUCTURE_1yqu| PDB=1yqu | SCENE= }}
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|RELATEDENTRY=[[1yqq|1YQQ]]
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|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1yqu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1yqu OCA], [http://www.ebi.ac.uk/pdbsum/1yqu PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1yqu RCSB]</span>
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}}
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'''Escherichia coli purine nucleoside phosphorylase II, the product of the xapA gene'''
'''Escherichia coli purine nucleoside phosphorylase II, the product of the xapA gene'''
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[[Category: Shugar, D.]]
[[Category: Shugar, D.]]
[[Category: Szczepanowski, R H.]]
[[Category: Szczepanowski, R H.]]
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[[Category: purine nucleoside phosphorylase guanine xanthine]]
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[[Category: Purine nucleoside phosphorylase guanine xanthine]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:39:57 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 01:18:28 2008''
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Revision as of 13:39, 3 May 2008

Template:STRUCTURE 1yqu

Escherichia coli purine nucleoside phosphorylase II, the product of the xapA gene


Overview

Purine nucleoside phosphorylases (PNPs, E. C. 2.4.2.1) use orthophosphate to cleave the N-glycosidic bond of beta-(deoxy)ribonucleosides to yield alpha-(deoxy)ribose 1-phosphate and the free purine base. Escherichia coli PNP-II, the product of the xapA gene, is similar to trimeric PNPs in sequence, but has been reported to migrate as a hexamer and to accept xanthosine with comparable efficiency to guanosine and inosine, the usual physiological substrates for trimeric PNPs. Here, we present a detailed biochemical characterization and the crystal structure of E.coli PNP-II. In three different crystal forms, PNP-II trimers dimerize, leading to a subunit arrangement that is qualitatively different from the "trimer of dimers" arrangement of conventional high molecular mass PNPs. Crystal structures are compatible with similar binding modes for guanine and xanthine, with a preference for the neutral over the monoanionic form of xanthine. A single amino acid exchange, tyrosine 191 to leucine, is sufficient to convert E.coli PNP-II into an enzyme with the specificity of conventional trimeric PNPs, but the reciprocal mutation in human PNP, valine 195 to tyrosine, does not elicit xanthosine phosphorylase activity in the human enzyme.

About this Structure

1YQU is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Escherichia coli purine nucleoside phosphorylase II, the product of the xapA gene., Dandanell G, Szczepanowski RH, Kierdaszuk B, Shugar D, Bochtler M, J Mol Biol. 2005 Apr 22;348(1):113-25. PMID:15808857 Page seeded by OCA on Sat May 3 16:39:57 2008

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