Kinetic Analysis of the Reaction Between d(TTGGCCAA) and Pt(NH3)3(H2O)2+ by Enzymatic Degradation of the Products and ESI and MALDI Mass Spectrometries

The kinetics of the reaction between the octanucleotide d(TTGGCCAA) in the single-stranded form in pure water and the platinum complex Pt(NH3)3(H2O)2+ was investigated by electrospray ionization and matrix-assisted laser desorption/ionization (MALDI) mass spectrometries coupled with enzymatic degradation of the adducts. These methods led to the determination of specific rate constants of platination. The global rate constant characteristic of the formation of adducts on each 5'- or 3'-guanine were measured by electrospray ionization analysis. The ratios between the 5'- and 3'-adducts were determined from enzymatic degradation of the final reaction mixture and MALDI analysis. The platination in water is approximately eight times faster than in 0.1 M NaClO4. The selectivity of platination is a factor of 2 in favor of the 5'-guanine, and similar to that observed for the reaction between d(CTGGCTCA) and Pt(NH3)3(H2O)2+ in 0.1 M NaClO4.