Binding properties of various metals to blood components and serum proteins: a multitracer study

The binding affinity of various trace elements to blood components and the pH-dependence of the binding affinity of the elements to serum proteins were examined using the radioactive multitracer technique. The binding affinity of 13 elements (Be, V, Mn, Zn, Se, Rb, Sr, Ce, Eu, Gd, Tm, Yb, and Lu) was simultaneously determined by gamma-ray spectrometry. The blood drawn from rats was separated into plasma, corpuscles, and erythrocyte ghosts. It was found that Be, Sr, Mn, and Zn bind highly to the plasma proteins. V and Se were highly bound to the corpuscles, and Se to the erythrocyte ghosts as well. Similar binding percentages of rare earth elements (Ce, Eu, Gd, Tm, Yb, and Lu) were found for each of the blood components, with the highest percentages being observed for plasma proteins. Albumin, beta-globulin, gamma-globulin, apotransferrin, and holotransferrin were examined in the study on the affinity of individual serum proteins. The pH dependence of the affinity of metal ions to the serum proteins in the pH range of 6.4-8.5 was examined using ultrafiltration and gamma-ray spectrometry. Each element showed a characteristic binding affinity to each serum protein, depending on pH. The results are discussed in terms of the chelating ability of metal ions and the nature of the serum proteins.