1xt4
From Proteopedia
(New page: 200px<br /><applet load="1xt4" size="450" color="white" frame="true" align="right" spinBox="true" caption="1xt4, resolution 2.01Å" /> '''Urate Oxidase From A...) |
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| - | [[Image:1xt4.gif|left|200px]]<br /><applet load="1xt4" size=" | + | [[Image:1xt4.gif|left|200px]]<br /><applet load="1xt4" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1xt4, resolution 2.01Å" /> | caption="1xt4, resolution 2.01Å" /> | ||
'''Urate Oxidase From Aspergillus Flavus Complexed With Guanine'''<br /> | '''Urate Oxidase From Aspergillus Flavus Complexed With Guanine'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Urate oxidase from Aspergillus flavus (uricase or Uox; EC 1.7.3.3) is a | + | Urate oxidase from Aspergillus flavus (uricase or Uox; EC 1.7.3.3) is a 135 kDa homotetramer with a subunit consisting of 301 amino acids. It catalyses the first step of the degradation of uric acid into allantoin. The structure of the extracted enzyme complexed with a purine-type inhibitor (8-azaxanthin) had been solved from high-resolution X-ray diffraction of I222 crystals. Expression of the recombinant enzyme in Saccharomyces cerevisiae followed by a new purification procedure allowed the crystallization of both unliganded and liganded enzymes utilizing the same conditions but in various crystal forms. Here, four different crystal forms of Uox are analyzed. The diversity of the Uox crystal forms appears to depend strongly on the chemicals used as inhibitors. In the presence of uracil and 5,6-diaminouracil crystals usually belong to the trigonal space group P3(1)21, the asymmetric unit (AU) of which contains one tetramer of Uox (four subunits). Chemical oxidation of 5,6-diaminouracil within the protein may occur, leading to the canonical (I222) packing with one subunit per AU. Coexistence of two crystal forms, P2(1) with two tetramers per AU and I222, was found in the same crystallization drop containing another inhibitor, guanine. Finally, a fourth form, P2(1)2(1)2 with one tetramer per AU, resulted fortuitously in the presence of cymelarsan, an additive. Of all the reported forms, the I222 crystal forms present by far the best X-ray diffraction resolution (approximately 1.6 angstroms resolution compared with 2.3-3.2 angstroms for the other forms). The various structures and contacts in all crystalline lattices are compared. The backbones are essentially conserved except for the region near the active site. Its location at the dimer interface is thus likely to be at the origin of the crystal contact changes as a response to the various bound inhibitors. |
==About this Structure== | ==About this Structure== | ||
| - | 1XT4 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_flavus Aspergillus flavus] with GUN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Urate_oxidase Urate oxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.7.3.3 1.7.3.3] Full crystallographic information is available from [http:// | + | 1XT4 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_flavus Aspergillus flavus] with <scene name='pdbligand=GUN:'>GUN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Urate_oxidase Urate oxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.7.3.3 1.7.3.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XT4 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Bonnete, F.]] | [[Category: Bonnete, F.]] | ||
[[Category: Castro, B.]] | [[Category: Castro, B.]] | ||
| - | [[Category: Hajji, M | + | [[Category: Hajji, M El.]] |
[[Category: Prange, T.]] | [[Category: Prange, T.]] | ||
[[Category: Retailleau, P.]] | [[Category: Retailleau, P.]] | ||
[[Category: Vivares, D.]] | [[Category: Vivares, D.]] | ||
| - | [[Category: h, N | + | [[Category: h, N Colloc.]] |
[[Category: GUN]] | [[Category: GUN]] | ||
[[Category: dimeric barrel]] | [[Category: dimeric barrel]] | ||
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[[Category: uric acid degradation]] | [[Category: uric acid degradation]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:58:21 2008'' |
Revision as of 13:58, 21 February 2008
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Urate Oxidase From Aspergillus Flavus Complexed With Guanine
Overview
Urate oxidase from Aspergillus flavus (uricase or Uox; EC 1.7.3.3) is a 135 kDa homotetramer with a subunit consisting of 301 amino acids. It catalyses the first step of the degradation of uric acid into allantoin. The structure of the extracted enzyme complexed with a purine-type inhibitor (8-azaxanthin) had been solved from high-resolution X-ray diffraction of I222 crystals. Expression of the recombinant enzyme in Saccharomyces cerevisiae followed by a new purification procedure allowed the crystallization of both unliganded and liganded enzymes utilizing the same conditions but in various crystal forms. Here, four different crystal forms of Uox are analyzed. The diversity of the Uox crystal forms appears to depend strongly on the chemicals used as inhibitors. In the presence of uracil and 5,6-diaminouracil crystals usually belong to the trigonal space group P3(1)21, the asymmetric unit (AU) of which contains one tetramer of Uox (four subunits). Chemical oxidation of 5,6-diaminouracil within the protein may occur, leading to the canonical (I222) packing with one subunit per AU. Coexistence of two crystal forms, P2(1) with two tetramers per AU and I222, was found in the same crystallization drop containing another inhibitor, guanine. Finally, a fourth form, P2(1)2(1)2 with one tetramer per AU, resulted fortuitously in the presence of cymelarsan, an additive. Of all the reported forms, the I222 crystal forms present by far the best X-ray diffraction resolution (approximately 1.6 angstroms resolution compared with 2.3-3.2 angstroms for the other forms). The various structures and contacts in all crystalline lattices are compared. The backbones are essentially conserved except for the region near the active site. Its location at the dimer interface is thus likely to be at the origin of the crystal contact changes as a response to the various bound inhibitors.
About this Structure
1XT4 is a Single protein structure of sequence from Aspergillus flavus with as ligand. Active as Urate oxidase, with EC number 1.7.3.3 Full crystallographic information is available from OCA.
Reference
Urate oxidase from Aspergillus flavus: new crystal-packing contacts in relation to the content of the active site., Retailleau P, Colloc'h N, Vivares D, Bonnete F, Castro B, El Hajji M, Prange T, Acta Crystallogr D Biol Crystallogr. 2005 Mar;61(Pt 3):218-29. Epub 2005, Feb 24. PMID:15735331
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