Interaction of apo-transferrin with anticancer ruthenium complexes NAMI-A and its reduced form

► Formation of Ru-apoTf adducts results in quenching of protein fluorescence. ► Reaction of NAMI-A with apo-Tf involves its aquation. ► The association constants for Ru-apoTf adducts is ca. 104 M− 1 at 37 °C. ► The reduced form of NAMI-A reacts with apo-Tf ca. 10 times slower. ► The percentage of ruthenium content in protein fractions is more than 30%.