Interaction between polylysine monolayer and DNA at the air-water interface

Masazo Niwa, Masa Aki Morikawa, Kenji Yagi, Nobuyuki Higashi

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16 Citations (Scopus)


The interaction of a polylysine amphiphile, which consists of a poly-L- or -D-lysine (1L or 1D) segment and two long alkyl chains at the C-terminus, with polynucleotides was studied with respect to the highly organized structure of polylysine assemblies on water. The results of surface pressure-area isotherm measurement showed that both of 1L and 1D formed stable monolayers on water in a neutral pH region. The secondary structure of polylysine segment for the surface monolayer was examined by means of circular dichroism and Fourier transform infrared spectroscopies. The helical structure was retained even at neutral pH, at which polylysine has been known to form a complete random coiled conformation in bulk solution. Protonated, positively charged and coiled 1L monolayer could interact electrostatically with guest polyanions including DNA in the subphase, and at the same time the conformation of the polylysine segment was converted from a random coil to an α-helix. Deprotonated, helical monolayers did not interact with single stranded polyadenylic acid, but with double stranded DNA. Double stranded DNA was found to interact more strongly with right-handed 1L monolayer than left-handed 1D monolayer. An obvious difference in the melting temperatures for these complexes was observed and discussed on the basis of difference in the interaction mode.

Original languageEnglish
Pages (from-to)47-54
Number of pages8
JournalInternational Journal of Biological Macromolecules
Issue number1
Publication statusPublished - Mar 8 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Economics and Econometrics
  • General Energy


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