Platination of superoxide dismutase with cisplatin: tracking the ammonia ligands using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS).

The high mass accuracy of FT-ICR MS combined with (15)N-labelling shows that mono- and di- platinated products from the reaction of erythrocyte superoxide dismutase with the anticancer drug cisplatin in solution retain their ammine ligands, in contrast to a recent X-ray crystallographic study.