1tfa
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OVOTRANSFERRIN, N-TERMINAL LOBE, APO FORM
OverviewOverview
Transferrins bind Fe3+ very tightly in a closed interdomain cleft by the, coordination of four protein ligands (Asp60, Tyr92, Tyr191, and His250 in, ovotransferrin N-lobe) and of a synergistic anion, physiologically, bidentate CO32-. Upon Fe3+ uptake, transferrins undergo a large scale, conformational transition: the apo structure with an opening of the, interdomain cleft is transformed into the closed holo structure, implying, initial Fe3+ binding in the open form. To solve the Fe3+-loaded, domain-opened structure, an ovotransferrin N-lobe crystal that had been, grown as the apo form was soaked with Fe3+-nitrilotriacetate, and its, structure was solved at 2.1 A resolution. The Fe3+-soaked form showed, almost exactly the same overall open structure as the iron-free apo form., The electron density map unequivocally proved the presence of an iron atom, with the coordination by the two protein ligands of Tyr92-OH and, Tyr191-OH. Other Fe3+ coordination sites are occupied by a, nitrilotriacetate anion, which is stabilized through the hydrogen bonds, with the peptide NH groups of Ser122, Ala123, and Gly124 and a side chain, group of Thr117. There is, however, no clear interaction between the, nitrilotriacetate anion and the synergistic anion binding site, Arg121.
About this StructureAbout this Structure
1TFA is a Single protein structure of sequence from Gallus gallus with SO4 as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Alternative structural state of transferrin. The crystallographic analysis of iron-loaded but domain-opened ovotransferrin N-lobe., Mizutani K, Yamashita H, Kurokawa H, Mikami B, Hirose M, J Biol Chem. 1999 Apr 9;274(15):10190-4. PMID:10187803
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