Spectral characterization of ruthenium (III) transferrin.

The interaction of ruthenium(III) with human serum transferrin has been investigated through UV/visible and CD spectroscopy. At physiological pH transferrin firmly binds two ruthenium(III) equivalents at the same sites of iron(III). Binding requires the presence of bicarbonate as synergistic anion. Metal uptake from ruthenium(III) nitrilotriacetate is complete within a few minutes; in contrast, uptake from ruthenium(III) chloride does not occur at a significant extent even over a period of days. The chemical properties of the obtained ruthenium/transferrin complex are described.