1iq7: Difference between revisions
New page: left|200px<br /><applet load="1iq7" size="450" color="white" frame="true" align="right" spinBox="true" caption="1iq7, resolution 2.3Å" /> '''Ovotransferrin, C-Ter... |
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[[Image:1iq7.jpg|left|200px]]<br /><applet load="1iq7" size=" | [[Image:1iq7.jpg|left|200px]]<br /><applet load="1iq7" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1iq7, resolution 2.3Å" /> | caption="1iq7, resolution 2.3Å" /> | ||
'''Ovotransferrin, C-Terminal Lobe, Apo Form'''<br /> | '''Ovotransferrin, C-Terminal Lobe, Apo Form'''<br /> | ||
==Overview== | ==Overview== | ||
The differential properties of anion-mediated Fe(3+) release between the | The differential properties of anion-mediated Fe(3+) release between the N- and C-lobes of transferrins have been a focus in transferrin biochemistry. The structural and kinetic characteristics for isolated lobe have, however, been documented with the N-lobe only. Here we demonstrate for the first time the quantitative Fe(3+) release kinetics and the anion-binding structure for the isolated C-lobe of ovotransferrin. In the presence of pyrophosphate, sulfate, and nitrilotriacetate anions, the C-lobe released Fe(3+) with a decelerated rate in a single exponential progress curve, and the observed first order rate constants displayed a hyperbolic profile as a function of the anion concentration. The profile was consistent with a newly derived single-pathway Fe(3+) release model in which the holo form is converted depending on the anion concentration into a "mixed ligand" intermediate that releases Fe(3+). The apo C-lobe was crystallized in ammonium sulfate solution, and the structure determined at 2.3 A resolution demonstrated the existence of a single bound SO(4)(2-) in the interdomain cleft, which interacts directly with Thr(461)-OG1, Tyr(431)-OH, and His(592)-NE2 and indirectly with Tyr(524)-OH. The latter three groups are Fe(3+)-coordinating ligands, strongly suggesting the facilitated Fe(3+) release upon the anion occupation at this site. The SO(4)(2-) binding structure supported the single-pathway kinetic model. | ||
==About this Structure== | ==About this Structure== | ||
1IQ7 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus] with NAG and SO4 as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 1IQ7 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus] with <scene name='pdbligand=NAG:'>NAG</scene> and <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IQ7 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Mikami, B.]] | [[Category: Mikami, B.]] | ||
[[Category: Mizutani, K.]] | [[Category: Mizutani, K.]] | ||
[[Category: Muralidhara, B | [[Category: Muralidhara, B K.]] | ||
[[Category: Tabata, S.]] | [[Category: Tabata, S.]] | ||
[[Category: Yamashita, H.]] | [[Category: Yamashita, H.]] | ||
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[[Category: transport protein]] | [[Category: transport protein]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:14:25 2008'' | ||
Revision as of 14:14, 21 February 2008
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Ovotransferrin, C-Terminal Lobe, Apo Form
OverviewOverview
The differential properties of anion-mediated Fe(3+) release between the N- and C-lobes of transferrins have been a focus in transferrin biochemistry. The structural and kinetic characteristics for isolated lobe have, however, been documented with the N-lobe only. Here we demonstrate for the first time the quantitative Fe(3+) release kinetics and the anion-binding structure for the isolated C-lobe of ovotransferrin. In the presence of pyrophosphate, sulfate, and nitrilotriacetate anions, the C-lobe released Fe(3+) with a decelerated rate in a single exponential progress curve, and the observed first order rate constants displayed a hyperbolic profile as a function of the anion concentration. The profile was consistent with a newly derived single-pathway Fe(3+) release model in which the holo form is converted depending on the anion concentration into a "mixed ligand" intermediate that releases Fe(3+). The apo C-lobe was crystallized in ammonium sulfate solution, and the structure determined at 2.3 A resolution demonstrated the existence of a single bound SO(4)(2-) in the interdomain cleft, which interacts directly with Thr(461)-OG1, Tyr(431)-OH, and His(592)-NE2 and indirectly with Tyr(524)-OH. The latter three groups are Fe(3+)-coordinating ligands, strongly suggesting the facilitated Fe(3+) release upon the anion occupation at this site. The SO(4)(2-) binding structure supported the single-pathway kinetic model.
About this StructureAbout this Structure
1IQ7 is a Single protein structure of sequence from Gallus gallus with and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Anion-mediated Fe3+ release mechanism in ovotransferrin C-lobe: a structurally identified SO4(2-) binding site and its implications for the kinetic pathway., Mizutani K, Muralidhara BK, Yamashita H, Tabata S, Mikami B, Hirose M, J Biol Chem. 2001 Sep 21;276(38):35940-6. Epub 2001 Jul 20. PMID:11466309
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