title: In vivo and in vitro studies of hafnium-binding to rat serum transferrin.
abstract: The binding of hafnium to rat serum transferrin was studied using the time differential perturbed angular correlation (TDPAC) technique. Hafnium is interesting as a toxic metal binding to transferrin because it behaves metabolically similarly to plutonium. The isotope 181Hf offers favorable access to the TDPAC-method. Samples were prepared in vivo by intravenous injection of Hf-NTA, Hf-citrate, and Hf-oxalate solutions, respectively, into Sprague-Dawley rats and in vitro by adding Hf-NTA solution to fresh rat serum. In both cases two specific electric quadrupole interactions were observed, which correspond to two well-defined binding configurations. They may be attributed to the N-terminal and the C-terminal binding site in the transferrin molecule. The 181Hf-distribution between these two binding states depends on pH, salt and hafnium concentrations, temperature, and incubation time. With a fast TDPAC-setup of four BaF2-detectors a time resolution of about 600 ps could be achieved. The specific binding configurations of 181Hf and the comparatively slow relaxation times lead to spectra of considerable accuracy.
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D006195:Hafnium / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011485:Protein Binding; D011868:Radioisotopes; D051381:Rats; D011919:Rats, Inbred Strains; D014168:Transferrin / Q000378:metabolism*
chemical_list: D001798:Blood Proteins; D011868:Radioisotopes; D014168:Transferrin; D006195:Hafnium