Preparation and properties of a single-sited fragment from the C-terminal domain of human transferrin.
A single-sited iron-binding fragment of human transferrin has been obtained by thermolysin cleavage of the protein, selectively loaded with iron in the C-terminal binding site, in a urea-containing buffer. The fragment contains carbohydrate, and hence derives from the C-terminal half of transferrin. Its metal-binding site accepts Fe3+ and Cu2+ with bicarbonate as accompanying anion, but only Fe3+ with oxalate as anion. EPR spectroscopic properties of the fragment are similar to those of the corresponding site in the intact protein. However, iron-binding by the fragment is weaker than by the C-terminal site of the intact protein, particularly at low pH, suggesting that overall as well as local protein conformation influences the metal-binding functions of the site.
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D001665:Binding Sites; D002241:Carbohydrates / Q000032:analysis; D003300:Copper / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000378:metabolism; D006801:Humans; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D007700:Kinetics; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism*; D013820:Thermolysin / Q000378:metabolism; D014168:Transferrin / Q000032:analysis*
D002241:Carbohydrates; D005290:Ferric Compounds; D010446:Peptide Fragments; D014168:Transferrin; D003300:Copper; D013820:Thermolysin