CONFORMATIONAL CHANGE IN DNA INDUCED BY CATIONIC BILAYER-MEMBRANES

The effect of synthetic cationic Lipids on the structure of DNA was st udied, The fluorescence enhancement of ethidium bromide on intercalati on into DNA was suppressed by the addition of bilayer-forming lipids, but not by micellar ones, Results on the fluorescence depolarization i ndex suggest that ethidium bromide is not released from DIVA by lipids intercalated into DNA. CD spectra of the DNA-lipid complexes revealed that the structure of DNA was changed only by bilayer-forming lipids at temperatures lower than their T-c values, Thus, the conformation of DNA is forced to change by cationic lipids forming the rigid bilayer membrane so that ethidium bromide fluorescence might be reduced, and t he conformation can be controlled by selection of the appropriate lipi d and temperature.