The Role of Transferrin in Actinide(IV) Uptake: Comparison with Iron(III)

• Published in: Chemistry : a European journal 2010-01, Vol.16 (4), p.1378-1387
• Main Authors: Jeanson, Aurélie, Ferrand, M., Funke, Harald, Hennig, Christoph, Moisy, Philippe, Solari, Pier Lorenzo, Vidaud, Claude, Den Auwer, Christophe
• Format: Article
• Language: English
• Subjects: actinides; Actinoid Series Elements - chemistry; Actinoid Series Elements - metabolism; Binding Sites; Chemistry; EXAFS spectroscopy; Humans; Hydrogen-Ion Concentration; Iron - blood; Iron - chemistry; Iron - metabolism; neptunium; Neptunium - chemistry; Neptunium - metabolism; plutonium; Plutonium - chemistry; Plutonium - metabolism; Spectrometry, Gamma; Spectrophotometry, Ultraviolet; Thorium - chemistry; Thorium - metabolism; transferrin; Transferrin - chemistry; Transferrin - physiology
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200901209

The impact of actinides on living organisms has been the subject of numerous studies since the 1950s. From a general point of view, these studies show that actinides are chemical poisons as well as radiological hazards. Actinides in plasma are assumed to be mainly complexed to transferrin, the iron carrier protein. This paper casts light on the uptake of actinides(IV) (thorium, neptunium, plutonium) by transferrin, focusing on the pH dependence of the interaction and on a molecular description of the cation binding site in the protein. Their behavior is compared with that of iron(III), the endogenous transferrin cation, from a structural point of view. Complementary spectroscopic techniques (UV/Vis spectrophotometry, microfiltration coupled with γ spectrometry, and X‐ray absorption fine structure) have been combined in order to propose a structural model for the actinide‐binding site in transferrin. Comparison of our results with data available on holotransferrin suggests some similarities between the behavior of FeIII and NpIV/PuIV/ NpIV is not complexed at pH