does the structure of surfactant complexes on the DNA surface depend on the nucleotide sequence?

Buckin, Morrissey, S. and Cragg, E.

Progress in Colloid and Polymer Science, 115, pp. 201-208 (2000)

We investigated the binding of surfactant to two double stranded oligonucleotides, each containing a high percentage (76%) of guanine— cytosine or adenine—thymine base pairs. A combination of isothermal titration calorimetry, UV spectroscopy, fluorescence and a highresolution ultrasonic technique were employed to gain both a structural and a thermodynamic insight into the complex formation. Binding of surfactant to the oligonucleotides was found to occur in two distinct stages. “Micellelike” surfactant aggregates are formed at the first stage of binding. These aggregates have a compressible core and are large enough to accommodate our fluorescence probe. The heat and compressibility effects at the first stage were found to be similar for the two duplexes, indicating that the overall structure and the thermodynamics of the surfactant aggregates are sequenceindependent. At the second stage, we observed the formation of large aggregates accompanied by light scattering in the visible region of the spectrum. In contrast, the structure and the thermodynamics of the ohgonucleotide—surfactant complexes formed at the second stage are dependent on the nucleotide sequence.

Additional Information Request