[1H,13C] NMR determination of the order of lobe loading of human transferrin with iron: comparison with other metal ions

FEBS Letters

Cox, Mark C¹  Li, Hongyan¹  Mason, Anne B²  Sun, Hongzhe¹  Sadler, Peter J¹  Woodworth, Robert C² 

[1] Department of Chemistry, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JJ, UK;Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT 05405, USA

关键词: Iron;    Metalloprotein;    Metal ion;    Nuclear magnetic resonance spectroscopy;    Transferrin;    DSC;    differential scanning calorimetry;    EDTA;    ethylenediaminetetraacetate;    EPR;    electron paramagnetic resonance;    HMQC;    heteronuclear multiple-quantum coherence;    hTF;    human serum transferrin;    hTF/2N;    N-lobe of hTF;    NTA;    nitrilotriacetate;    pH*;    pH meter reading in D2O;   

DOI  :  10.1016/S0014-5793(98)00034-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Human serum transferrin (hTF) is a single-chain bilobal glycoprotein (80 kDa) which transports Fe³⁺ and a variety of other metal ions in blood. Only diferric transferrin, not the apo-protein, binds strongly to transferrin receptors and is taken up by cells via receptor-mediated endocytosis. We show here that 2D [¹H,¹³C] NMR studies of recombinant ϵ-[¹³C]Met-hTF allow the order of lobe loading with various metal ions, including Fe³⁺, to be determined. In particular, the resonance for Met-464, a residue in the hydrophobic patch of helix 5, is very sensitive to iron binding in the C-lobe. The selectivity of lobe loading with Fe³⁺ is compared to loading with Fe²⁺ (which binds as Fe³⁺), Al³⁺, Ga³⁺ and Bi³⁺. Similar changes in shifts of the Met residues are observed for these metal ions, suggesting that they induce similar conformational changes in the protein.

【 授权许可】

Unknown