Abstract
Differential scanning calorimetry (DSC) of several plasmid DNAs was carried out. The DSC curves for the DNAs linearized with a restriction enzyme provided several peaks due to the stepwise transition of double-stranded DNA to single-stranded DNA along the molecular chain. These DSC curves are very similar to the melting profiles constructed by calculation from the entire base sequences of these plasmids according to the helix-coil transition theory. The theoretical analysis shows that the boundaries of cooperative melting regions of the DNA coincide with the end regions of each of the coding regions. The interaction between various drugs and plasmid DNA was also studied by the DSC method. The DSC curves of DNA in the presence of drugs are affected in the characteristic manner depending upon the interaction mode of the drug, demonstrating that DSC method is very useful for the study of the drug-DNA interaction.
