Study of the reactions between platinum(II) complexes and L-methionine in the presence and absence of 5'-GMP.

The reactions of the platinum(II) complexes, Pt(dien)(H(2)O), PtCl(dien) and PtBr(dien) (dien is diethylenetriamine) with some biologically relevant ligands such as inosine (INO), inosine-5'-monophosphate (5'-IMP), guanosine-5'-monophosphate (5'-GMP), glutathione (GSH) and l-methionine (S-meth), have been studied by UV-Visible spectrophotometry and (1)H NMR spectroscopy. Kinetic and thermodynamic parameters of these reactions were determined. Competitive reactions of PtCl(dien) with l-methionine and 5'-GMP demonstrated initially rapid formation of Pt(dien)(S-meth) followed by displacement of l-methionine by 5'-GMP. In the later stages the concentration of Pt(dien)(N7-GMP) is predominant. The results are analyzed in reference to the anti-tumour activity of Pt(II) complexes.