SELECTIVE DISPLACEMENT OF S-BOUND L-METHIONINE ON PLATINUM BY HISTIDINE-CONTAINING LIGANDS

Reactions of three histidine-containing ligands (N-acetyl-L-histidine, N-acetylglycyl-L-histidine and N-acetyl-L-histidylglycine) with the m onofunctional [Pt(dien)(L-Met-S)](+) complex have been studied by H-1 NMR spectroscopy. The reactions were carried out at room temperature i n 50 mM phosphate buffer at pD 7.4. The results have shown that very s low intermolecular displacement (k = ca. 10(-6) M-1 s(-1)) of S-bound L-Met on platinum occurs by the N3 atom of the imidazole ring in the h istidyl residue.