Role of Linker Groups between Hydrophilic and Hydrophobic Moieties of Cationic Surfactants on Oligonucleotide-Surfactant Interactions

The interaction between DNA and amino-acid-based surfactants with different linker groups was investigated by gel electrophoresis, ethidium bromide exclusion assays, circular dichroism, and melting temperature determinations. The Studies showed that the strength of the interaction between the oligonucleotides and the surfactants is highly dependent oil the linker of the surfactant. For ester surfactants, no significant interaction was observed for surfactant-to-DNA charge ratios tip to 12. On the other hand, amide surfactants were shown to interact strongly with the oligonucleotides; these surfactants could displace up to 75% of the ethidium bromide molecules bound to the DNA and induced significant changes in the circular dichroism spectra. When comparing the headgroups of the surfactants, it was observed that surfactants with more hydrophobic headgroups (proline vs alanine) interacted more strongly With the DNA, in good agreement With previous studies.