In vitro binding of platinum compounds to human transferrin

The binding of the antineoplastic drug cis-dichlorodiammineplatinum II (CDDP) and a related complex, potassium tetrachloroplatinite (K2PtCl4), to human transferrin in buffered anion solutions was studied over a period of two weeks. Separation of bound and free platinum was accomplished by gel chromatography with platinum analysis by atomic absorption spectrophotometry. The results demonstrated that K2PtCl4 was bound to a greater degree than CDDP in this system with 3-5 and 1-2 platinum atoms respectively, bound per transferrin molecule. However, it appears this interaction, which may involve the specific cation binding sites, does not play a significant role in the pharmacology of CDDP in vivo.