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Updated: Jul 27, 2026

Genome-wide Mapping of Drug-DNA Interactions in Cells with COSMIC (Crosslinking of Small Molecules to Isolate Chromatin)
Published on: January 20, 2016
Nonspecific interactions in dye binding to DNA. Influence of alcohols and amides
G Varani1, L Della Torre, G Baldini
1Dipartimento di Fisica, Università di Milano, Italy.
Abstract:
The binding of a few drugs (ethidium bromide, propidium diiodide, proflavine and actinomycin D) to DNA has been investigated in aqueous solutions to which cosolvents of different polarity have been added. It is found that both alcohols (less polar than water) and amides (more polar) lower the binding constant according to a linear relationship between the intercalation free energy and cosolvent concentration. The main action of cosolvents cannot be described in terms of electrostatic effects, since they predict much smaller changes in the binding constant than those observed. It appears instead that relevant solvation effects are responsible for the binding strength of the different dyes to DNA. As a general result, it is found that solvation effects largely contribute to the intercalation free energy, thereby weakening the influence of nonspecific interactions at the intercalation site.
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