Cyclodextrins in DNA decompaction

Individual T4DNA molecules, previously compacted by using a cationic surfactant (cetyltrimethylammonium bromide, CTAB), were successfully decompacted by the addition of an appropriate concentration of either α-cyclodextrin or β-cyclodextrin (α-CD and β-CD, respectively) due to the formation of inclusion complexes with the surfactant. The process was shown to be a non first-order transition from globules to coils. Density and sound velocity measurements as well as steady state fluorescence spectroscopy have confirmed the approximate CD concentration at which the globule-to-coil transition occurs. Phase maps of the DNA–CTA–CD systems were produced and the CTAB concentration range at which decompaction can be achieved was determined. Evidences for DNA–CD interaction were found, however, its nature and influence on the decompaction process was not yet determined.