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Merck

Interaction of cationic surfactants with DNA: a single-molecule study.

Nucleic acids research (2008-01-22)
Sudhir Husale, Wilfried Grange, Marc Karle, Stephan Bürgi, Martin Hegner
ANOTACE

The interaction of cationic surfactants with single dsDNA molecules has been studied using force-measuring optical tweezers. For hydrophobic chains of length 12 and greater, pulling experiments show characteristic features (e.g. hysteresis between the pulling and relaxation curves, force-plateau along the force curves), typical of a condensed phase (compaction of a long DNA into a micron-sized particle). Depending on the length of the hydrophobic chain of the surfactant, we observe different mechanical behaviours of the complex (DNA-surfactants), which provide evidence for different binding modes. Taken together, our measurements suggest that short-chain surfactants, which do not induce any condensation, could lie down on the DNA surface and directly interact with the DNA grooves through hydrophobic-hydrophobic interactions. In contrast, long-chain surfactants could have their aliphatic tails pointing away from the DNA surface, which could promote inter-molecular interactions between hydrophobic chains and subsequently favour DNA condensation.

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Sigma-Aldrich
Trimethyloctylammonium chloride, ≥97.0% (AT)
Sigma-Aldrich
Trimethyloctylammonium bromide, ≥98.0% (AT)