COMPARATIVE ANALYSIS OF THE EFFECTS OF PLATINUM COMPOUNDS ON THERMOSTABILITY OF DNA

The thermal denaturation profiles of Calf Thymus DNA in the presence of binuclear compounds of bivalent platinum (cis-[{Pt(NH3)2Cl}2Pyr]Cl2) were studied by absorption spectrophotometry and differential adiabatic scanning microcalorimetry. A comparison with an active antitumor drug cis-diamminedichloroplatinum (cis-DDP) was made. Experimental data witness that small concentrations (r<0.3) of binuclear platinum compound stabilized the structure of Calf Thymus DNA stronger than cis-DDP. Both the complexes tend to refold the denaturated DNA. It is rather interesting that in case of 10-6 M concentration of binuclear platinum compound (r=0.03) the denaturated DNA is refolded by 77.62%, whereas under the same condition cis-DDP leads to 49.01% refolding of denaturated DNA. Such a high percent of renaturation was probably the result of interstrand cross-links formation.