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| {{STRUCTURE_1iq7| PDB=1iq7 | SCENE= }} | | {{STRUCTURE_1iq7| PDB=1iq7 | SCENE= }} |
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| '''Ovotransferrin, C-Terminal Lobe, Apo Form'''
| | ===Ovotransferrin, C-Terminal Lobe, Apo Form=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_11466309}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11466309 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11466309}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Transferrin]] | | [[Category: Transferrin]] |
| [[Category: Transport protein]] | | [[Category: Transport protein]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 20:16:33 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 13:47:52 2008'' |
