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The method presented here enables the isolation of three monofunctional adducts. These are: platination of cytosine, adenine and guanosine. The three detected bifunctional complexes were: guanine N7 to N7, adenine N7 to N7 and adenine N7 to N1. A mixed bifunctional complex of guanine and adenosine and the product of polymerization of three adenines and two moieties of cis DDP were also detected. In the peak eluted separately from the guanine standard, no Pt was detected. The sample eluted in this peak had UV spectrum different from the standard and may represent the degraded product of guanine and polymerized Pt.

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.

Mono- and bifunctional complexes of cis DDP and d-guanosine were isolated on Sephadex G-25. The presence of cysteine in incubation mixture resulted in the vanishing of bifunctional complex of d-guanosine and the appearance of d-guanosine-cis DDP-cysteine complex in the eluted peak. It is also possible that the eluted peak contained no homogeneous product of the reaction.