The influence of methionine-containing peptides on the reaction of carboplatin with 5'-guanosine monophosphate: a comparison with cisplatin.
The pH- and time-dependent reaction of the anticancer drug carboplatin, [Pt(cbdca-kappa(2)O,O')(NH(3))(2)] (cbdca=cyclobutane-1,1-dicarboxylate), with the tripeptides H-glyglymet-OH (glycylglycyl-L-methionine) and Ac-glyglymet-OH at 313 K was investigated by high-performance liquid chromatography, NMR and mass spectrometry. The relative stability of the initial ring-opened kappaS complex [Pt(cbdca-kappaO)(Ac-glyglymet-OH-kappaS)(NH(3))(2)] leads to increased formation of the kinetically favoured kappaS:kappaS' bis-adduct [Pt(Ac-glyglymet-OH-kappaS)(2)(NH(3))(2)](2+) in comparison with cisplatin. As a result a second 1:2 reaction pathway kappaS-->kappaS:kappaS'-->kappa(2)N(M), S:kappaS'-->kappa(3)N(G2),N(M), S:kappaS', where N(M) and N(G2) represent, respectively, metallated methionine and glycine nitrogen atoms, competes with the 1:1 route kappaS-->kappa(2)N(M), S-->kappa(3)N(G2),N(M), S also observed for cisplatin. Cleavage of N-acetylglycine at the backbone C(O)-N bond to the second gly residue (G2) is observed after 100 h for the respective tridentate complexes [Pt(Ac-glyglyH(-1)metH(-1)-OH-kappa(3)N(G2),N(M), S) (Ac-glyglymet-OH-kappaS)] and [Pt(Ac-glyglyH(-1)metH(-1)-OH-kappa(3)N(G2),N(M), S)(NH(3))] at pH <5.2. The longevity of the initial kappaS complex leads to about an eight-fold increase in the rate of formation of the kappaN7:kappaN7' bis-adduct [Pt(5'-GMP-kappaN7)(2)(NH(3))(2)](2-) for the reaction of carboplatin with 5'-GMP(2-) at pH 7 in the presence of Ac-glyglymet-OH. A mixed-ligand kappaS:kappaN7 species [Pt(5'-GMP-kappaN7)(Ac-glyglymet-OH-kappaS)(NH(3))(2)] provides the major precursor for this 1:2 nucleotide complex and kappaN7 coordination of 5'-GMP(2-) is also observed in the kappa(2)N(M),S:kappaN7 complex [Pt(5'-GMP-kappaN7)(Ac-glyglymetH(-1)-OH-kappa(2)N(M),S)(NH(3))(2)](-) formed by substitution of the ammine ligand trans to the methionine sulphur. As the intermediate kappaS:kappaN7 species is formed rapidly within the first 10 h of reaction, these results suggest that the transfer reaction pathway kappaS-->kappaS:kappaN7-->kappaN7:kappaN7' involving kappaS platinated peptides could play an important role in accelerating the rate of DNA binding for carboplatin.
Lehrstuhl für Analytische Chemie, Ruhr-Universität Bochum, D-44780, Bochum, Germany.
Marco
M
Kleine
Dirk
D
Wolters
William S
WS
Sheldrick
D000970:Antineoplastic Agents / Q000737:chemistry / Q000378:metabolism*; D001667:Binding, Competitive; D016190:Carboplatin / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002945:Cisplatin / Q000737:chemistry / Q000378:metabolism*; D006157:Guanosine Monophosphate / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008715:Methionine / Q000737:chemistry / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013997:Time Factors
D000970:Antineoplastic Agents; D009842:Oligopeptides; D006157:Guanosine Monophosphate; D008715:Methionine; D016190:Carboplatin; D002945:Cisplatin