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

Abstract

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 α-chain, heme-α, β-chain, and heme-β 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-µM to µM 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.