The effect of ionic strength on melting of DNA modified by platinum(II) complexes
Language English Country Netherlands Media print
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
8679924
DOI
10.1016/0301-4622(96)00010-5
PII: 0301462296000105
Knihovny.cz E-resources
- MeSH
- Antineoplastic Agents chemistry pharmacology MeSH
- Chemical Phenomena MeSH
- Chemistry, Physical MeSH
- Nucleic Acid Denaturation drug effects MeSH
- DNA chemistry drug effects MeSH
- Molecular Sequence Data MeSH
- Organoplatinum Compounds chemistry pharmacology MeSH
- Osmolar Concentration MeSH
- Base Sequence MeSH
- Cattle MeSH
- Animals MeSH
- Check Tag
- Cattle MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Antineoplastic Agents MeSH
- DNA MeSH
- Organoplatinum Compounds MeSH
Thermal denaturation of calf thymus DNA modified by antitumor cis-diamminedichloroplatinum(II) (cis-DDP) and by two related Pt(II) compounds which had been shown to be clinically ineffective, viz. trans-diamminedichloroplatinum(II) (trans-DDP) or monodentate diethylenetriaminechloroplatinum(II) chloride [[Pt(dien)Cl)]Cl], was studied by monitoring changes of absorbance at 260 nm. The melting of DNA platinated to different levels was investigated in neutral media containing varying concentrations of Na+. It has been shown that the ionic strength has a strong influence on the character and magnitude of changes in the melting temperature of DNA (Tm) induced by the platination. The modification of DNA by either platinum complex used in this work results in an increase of Tm if DNA melting is measured in media containing low Na+ concentrations (ca. 1 mM). This effect is reversed at higher Na+ concentrations. The concentration of Na+ at which this reversal occurs is, however, markedly lower for DNA modified by cis-DDP than for DNA modified by the other two platinum complexes. These results have been interpreted to mean that at least three factors affect the thermal stability of DNA modified by the platinum(II) complexes: stabilization effects of the positive charge on the platinum moiety and of interstand cross-links, and a destabilization effect of conformational distortions in DNA. Thus, in order to compare and interpret the melting behavior of DNA modified by different compounds, a great attention has to be paid to the composition of the medium in which the melting experiments are carried out.
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