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1qi9
From Proteopedia
(New page: 200px<br /><applet load="1qi9" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qi9, resolution 2.05Å" /> '''X-RAY SIRAS STRUCTUR...) |
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| - | [[Image:1qi9.jpg|left|200px]]<br /><applet load="1qi9" size=" | + | [[Image:1qi9.jpg|left|200px]]<br /><applet load="1qi9" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1qi9, resolution 2.05Å" /> | caption="1qi9, resolution 2.05Å" /> | ||
'''X-RAY SIRAS STRUCTURE DETERMINATION OF A VANADIUM-DEPENDENT HALOPEROXIDASE FROM ASCOPHYLLUM NODOSUM AT 2.0 A RESOLUTION'''<br /> | '''X-RAY SIRAS STRUCTURE DETERMINATION OF A VANADIUM-DEPENDENT HALOPEROXIDASE FROM ASCOPHYLLUM NODOSUM AT 2.0 A RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The homo-dimeric structure of a vanadium-dependent haloperoxidase (V-BPO) | + | The homo-dimeric structure of a vanadium-dependent haloperoxidase (V-BPO) from the brown alga Ascophyllum nodosum (EC 1.1.11.X) has been solved by single isomorphous replacement anomalous scattering (SIRAS) X-ray crystallography at 2.0 A resolution (PDB accession code 1QI9), using two heavy-atom datasets of a tungstate derivative measured at two different wavelengths. The protein sequence (SwissProt entry code P81701) of V-BPO was established by combining results from protein and DNA sequencing, and electron density interpretation. The enzyme has nearly an all-helical structure, with two four-helix bundles and only three small beta-sheets. The holoenzyme contains trigonal-bipyramidal coordinated vanadium atoms at its two active centres. Structural similarity to the only other structurally characterized vanadium-dependent chloroperoxidase (V-CPO) from Curvularia inaequalis exists in the vicinity of the active site and to a lesser extent in the central four-helix bundle. Despite the low sequence and structural similarity between V-BPO and V-CPO, the vanadium binding centres are highly conserved on the N-terminal side of an alpha-helix and include the proposed catalytic histidine residue (His418(V-BPO)/His404(V-CPO)). The V-BPO structure contains, in addition, a second histidine near the active site (His411(V-BPO)), which can alter the redox potential of the catalytically active VO2-O2 species by protonation/deprotonation reactions. Specific binding sites for the organic substrates, like indoles and monochlordimedone, or for halide ions are not visible in the V-BPO structure. A reaction mechanism for the enzymatic oxidation of halides is discussed, based on the present structural, spectroscopic and biochemical knowledge of vanadium-dependent haloperoxidases, explaining the observed enzymatic differences between both enzymes. |
==About this Structure== | ==About this Structure== | ||
| - | 1QI9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Ascophyllum_nodosum Ascophyllum nodosum] with VO4 and IOD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Chloride_peroxidase Chloride peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.10 1.11.1.10] Full crystallographic information is available from [http:// | + | 1QI9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Ascophyllum_nodosum Ascophyllum nodosum] with <scene name='pdbligand=VO4:'>VO4</scene> and <scene name='pdbligand=IOD:'>IOD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Chloride_peroxidase Chloride peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.10 1.11.1.10] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QI9 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Chloride peroxidase]] | [[Category: Chloride peroxidase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Hecht, H | + | [[Category: Hecht, H J.]] |
[[Category: Kiess, M.]] | [[Category: Kiess, M.]] | ||
| - | [[Category: Liaud, M | + | [[Category: Liaud, M F.]] |
[[Category: Schomburg, D.]] | [[Category: Schomburg, D.]] | ||
[[Category: Vilter, H.]] | [[Category: Vilter, H.]] | ||
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[[Category: vanadium]] | [[Category: vanadium]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:39:52 2008'' |
Revision as of 12:39, 21 February 2008
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X-RAY SIRAS STRUCTURE DETERMINATION OF A VANADIUM-DEPENDENT HALOPEROXIDASE FROM ASCOPHYLLUM NODOSUM AT 2.0 A RESOLUTION
Overview
The homo-dimeric structure of a vanadium-dependent haloperoxidase (V-BPO) from the brown alga Ascophyllum nodosum (EC 1.1.11.X) has been solved by single isomorphous replacement anomalous scattering (SIRAS) X-ray crystallography at 2.0 A resolution (PDB accession code 1QI9), using two heavy-atom datasets of a tungstate derivative measured at two different wavelengths. The protein sequence (SwissProt entry code P81701) of V-BPO was established by combining results from protein and DNA sequencing, and electron density interpretation. The enzyme has nearly an all-helical structure, with two four-helix bundles and only three small beta-sheets. The holoenzyme contains trigonal-bipyramidal coordinated vanadium atoms at its two active centres. Structural similarity to the only other structurally characterized vanadium-dependent chloroperoxidase (V-CPO) from Curvularia inaequalis exists in the vicinity of the active site and to a lesser extent in the central four-helix bundle. Despite the low sequence and structural similarity between V-BPO and V-CPO, the vanadium binding centres are highly conserved on the N-terminal side of an alpha-helix and include the proposed catalytic histidine residue (His418(V-BPO)/His404(V-CPO)). The V-BPO structure contains, in addition, a second histidine near the active site (His411(V-BPO)), which can alter the redox potential of the catalytically active VO2-O2 species by protonation/deprotonation reactions. Specific binding sites for the organic substrates, like indoles and monochlordimedone, or for halide ions are not visible in the V-BPO structure. A reaction mechanism for the enzymatic oxidation of halides is discussed, based on the present structural, spectroscopic and biochemical knowledge of vanadium-dependent haloperoxidases, explaining the observed enzymatic differences between both enzymes.
About this Structure
1QI9 is a Single protein structure of sequence from Ascophyllum nodosum with and as ligands. Active as Chloride peroxidase, with EC number 1.11.1.10 Full crystallographic information is available from OCA.
Reference
X-ray structure determination of a vanadium-dependent haloperoxidase from Ascophyllum nodosum at 2.0 A resolution., Weyand M, Hecht H, Kiess M, Liaud M, Vilter H, Schomburg D, J Mol Biol. 1999 Oct 29;293(3):595-611. PMID:10543953
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