Estimation of the extent of platination and the sites of Pt binding after interaction of cis- and trans-diamminedichloroplatinum(II) with DNA and chromatin.

Differences in the mode of binding of cis- and trans-diamminedichloroplatinum(II) complexes (cis and trans-DDP) with DNA and chromatin were studied with the use of [14C]methylbromphenvinphos as an alkylating agent which attacks the sites in purines bases involved also in the reaction with cis-DDP (Oliński et al., J. Biochem. Biophys. Meth., 7, 171-173, 1983). Methylation of pre-formed DDP-DNA and DDP-chromatin complexes, followed by qualitative and quantitative analysis of the methylation products in DNA hydrolysates, permitted evaluation of the distribution and extent of platination of the bases. No major differences were found between the action of the two DDP isomers on DNA. However, a significant decrease in binding of trans-DDP to adenine moieties was observed when the interaction of cis- and trans-DDP on chromatin was compared.