Independent versus cooperative binding in polyethylenimine-DNA and poly(l-lysine)-DNA polyplexes

Tiia Maaria Ketola, Martina Hanzlíková, Linda Leppänen, Manuela Raviña, Corey J. Bishop, Jordan J. Green, Arto Urtti, Helge Lemmetyinen, Marjo Yliperttula, Elina Vuorimaa-Laukkanen

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23 Scopus citations


The mechanism of polyethylenimine-DNA and poly(l-lysine)-DNA complex formation at pH 5.2 and 7.4 was studied by a time-resolved spectroscopic method. The formation of a polyplex core was observed to be complete at approximately N/P = 2, at which point nearly all DNA phosphate groups were bound by polymer amine groups. The data were analyzed further both by an independent binding model and by a cooperative model for multivalent ligand binding to multisubunit substrate. At pH 5.2, the polyplex formation was cooperative at all N/P ratios, whereas for pH 7.4 at N/P < 0.6 the polyplex formation followed independent binding changing to cooperative binding at higher N/Ps.

Original languageEnglish (US)
Pages (from-to)10405-10413
Number of pages9
JournalJournal of Physical Chemistry B
Issue number36
StatePublished - Sep 12 2013

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry


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