Reaction of cisplatin analogs with selenomethionine

Rebekkah Lively, Stephen C. Chmely, and Kevin Williams

Analogs of the platinum anticancer compound cisplatin have been reacted with the nonstandard amino acid selenomethionine (SeMet) and characterized by NMR spectroscopy. SeMet was found to react faster than methionine (Met) with a representative analog platinum complex (Pt(dien)) containing only one coordination site; however, over time, equal amounts of the SeMet and Met products were observed. Thus, both SeMet and Met products have similar thermodynamic stabilities, but SeMet is kinetically faster to react. Platinum complexes with two available coordination sites have also been studied, since these complexes more closely resemble cisplatin. Three different types of products have been observed, although the size and shape of the other ligands on the platinum atom can limit which of these complexes form.