title: Interaction of vanadium(IV) with human serum apo-transferrin.
abstract: The interaction of V(IV)O-salts as well as of a few V(IV)O(carrier)n complexes with human serum transferrin (hTF) is studied focusing on the determination of the nature and stoichiometry of the binding of V(IV)O(2+) to hTF, as well as whether the conformation of hTF upon binding to V(IV)O(2+) or to its complexes is changed. Circular dichroism (CD) spectra measured for solutions containing V(IV)O(2+) and apo-hTF, and V(IV)O-maltol and apo-hTF, clearly indicate that hTF-V(IV)O-maltol ternary species form with a V(IV)O:maltol stoichiometry of 1:1. For V(IV)O salts and several V(IV)O(carrier)n complexes (carrier ligand=maltolato, dhp, picolinato and dipicolinato) (Hdhp=1,2-dimethyl-3-hydroxy-4-pyridinone) the maximum number of V(IV)O(2+) bound per mole of hTF is determined to be ~2 or lower in all cases. The binding of V(IV)O to apo-hTF most certainly involves several amino acid residues of the Fe-binding site, and as concluded by urea gel electrophoresis experiments, the formation of (V(IV)O)2hTF species may occur with the closing of the hTF conformation as is the case in (Fe(III))2hTF, which is an essential feature for the transferrin receptor recognition.
authors: Centro Química Estrutural, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors: Sameena
authors: S
authors: Mehtab
authors: Gisela
authors: G
authors: Gonçalves
authors: Somnath
authors: S
authors: Roy
authors: Ana Isabel
authors: AI
authors: Tomaz
authors: Teresa
authors: T
authors: Santos-Silva
authors: Marino F A
authors: MF
authors: Santos
authors: Maria J
authors: MJ
authors: Romão
authors: Tamás
authors: T
authors: Jakusch
authors: Tamás
authors: T
authors: Kiss
authors: João Costa
authors: JC
authors: Pessoa
mesh_terms: D001059:Apoproteins / Q000737:chemistry*; D001665:Binding Sites; D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007501:Iron / Q000737:chemistry*; D010848:Picolinic Acids / Q000737:chemistry; D011485:Protein Binding; D011753:Pyrones / Q000737:chemistry; D012996:Solutions; D014168:Transferrin / Q000737:chemistry*; D014508:Urea; D014639:Vanadium / Q000737:chemistry*
chemical_list: D001059:Apoproteins; D010848:Picolinic Acids; D011753:Pyrones; D012996:Solutions; D014168:Transferrin; C028284:apotransferrin; D014639:Vanadium; C008316:maltol; D014508:Urea; D007501:Iron; C030614:picolinic acid; C004860:dipicolinic acid