Molecular assembling of DNA with amphipathic peptides.

The self-assembling of double-stranded DNA with short synthetic peptides has been analysed using the fluorescent properties of the intercalating dye, ethidium bromide. Two membrane-active peptides with appropriate sequences of lysine and leucine amino acids and a short polylysine have been probed. The results revealed that the secondary structure of the peptide decisively aimed the peptide-DNA complex formation: only the longest peptide, which is the only one to exhibit an alpha-helical structure in solution, could achieve DNA compacting before charge neutralisation. The obtained complex retained a significant membrane activity as demonstrated by calcein leakage experiments. This shows that short synthetic peptides of elementary sequence can combine both membrane activity and DNA-condensing properties. The potential of these constructs as DNA carriers will be discussed.