Studies of cisplatin and hemoglobin interactions using nanospray mass spectrometry and liquid chromatography with inductively-coupled plasma mass spectrometry

Interactions of cisplatin with hemoglobin (Hb) were studied using both nanoelectrospray mass spectrometry (nanoESI-MS) and a combination of size exclusion high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICPMS). Size exclusion HPLC separation of free and protein-bound cisplatin followed by simultaneous monitoring of 195Pt and 57Fe demonstrated the presence of Hb-bound Pt complexes. Nanospray quadrupole time-of-flight mass spectrometry studies of the Hb-cisplatin complexes further demonstrated the specific binding of cisplatin to the alpha-chain, heme-alpha, beta-chain, and heme-beta units of hemoglobin. Accurate mass measurements and tandem mass spectrometry information confirmed the Hb-cisplatin complexes. The formation of Hb-cisplatin complexes was observed at the sub-microM to microM concentration levels of cisplatin, which are relevant to clinical levels. These findings and the techniques developed for cisplatin-Hb interaction studies are useful for understanding of drug-protein interactions.