[DNA-phospholipid interactions. A study using lipid-specific fluorescent and photoreactive probes]

The interaction of phospholipids with phage T7 DNA was investigated using anthryl-vinyl-labeled and photoactivable phosphatidylcholine and sphingomyelin. Fluorescence polarization studies demonstrated that, in the presence of DNA, the fluorophore mobility is diminished as its distance from the polar head-group is increased. Immobilization of lipid chains is enhanced by Ca2+ ions, the effect being more pronounced for sphingomyelin than for phosphatidylcholine derivatives. On the other hand, phospholipids with a photoactivable group could not be crosslinked to DNA in the DNA-phospholipid complexes, evidencing against the presence of contacts between lipids and DNA.