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Formation of titanium(IV) transferrin by reaction of human serum apotransferrin with titanium complexes
Author(s) -
Messori Luigi,
Orioli Pierluigi,
Banholzer Vivien,
Pais Istvan,
Zatta Paolo
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01651-2
Subject(s) - transferrin , titanium , chemistry , adduct , nuclear chemistry , chloride , inorganic chemistry , biochemistry , organic chemistry
The reaction of human serum apotransferrin with titanium(IV) citrate under physiological conditions results in the formation of a specific bis‐titanium(IV) transferrin adduct (Ti 2 Tf hereafter) with two titanium(IV) ions loaded at the iron binding sites. The same specific Ti 2 Tf complex is formed by reacting apotransferrin with titanium(III) chloride and exposing the sample to air. The derivative thus obtained was characterized by spectroscopic techniques, including absorption, UV difference, circular dichroism and 13 C NMR spectroscopies, and shown to be stable within the pH range 5.5–9.0. Surprisingly, the reaction of apoTf with titanium(IV) nitrilotriacetate (NTA) does not lead to formation of appreciable amounts of Ti 2 Tf, even after long incubation times, although some weak interactions of Ti(IV)NTA with apoTf are spectroscopically detected. Implications of the present results for a role of transferrin in the uptake, transport and delivery of soluble titanium(IV) compounds under physiological conditions are discussed.