Reentrant phase transitions of DNA-surfactant complexes.
Complexes of double-stranded DNA with the cationic surfactant cetyltrimethylammonium bromide have been studied using small angle x-ray diffraction at varying concentrations of DNA and the cosurfactant hexanol. At low DNA concentrations, an intercalated hexagonal (H(c)(I))-->lamellar (L(c)(alpha))-->inverted hexagonal (H(c)(II)) transformation is found on increasing hexanol content. The H(c)(II) structure is converted into L(c)(alpha) on adding more DNA. Further increase in hexanol content leads to a phase separation in the surfactant solution, and a reentrant L(c)(alpha)-->H(c)(II)-->L(c)(alpha) transition is observed as DNA concentration is increased. Such structural transformations of DNA-surfactant complexes, driven by DNA concentration, have not been reported until now.
Krishnaswamy
Rema
R
Raman Research Institute, Bangalore 560 080, India.
Raghunathan
V A
VA
Sood
A K
AK
D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D045424:Complex Mixtures / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D000441:Hexanols / Q000737:chemistry*; D046911:Macromolecular Substances; D009690:Nucleic Acid Conformation; D044367:Phase Transition; D012996:Solutions; D013501:Surface-Active Agents / Q000737:chemistry*; D014961:X-Ray Diffraction / Q000379:methods*
D002593:Cetrimonium Compounds; D045424:Complex Mixtures; D000441:Hexanols; D046911:Macromolecular Substances; D012996:Solutions; D013501:Surface-Active Agents; D004247:DNA; D000077286:Cetrimonium