Behaviour of inorganic and organic cations in the Debye-Hückel layer of DNA

Pier Giorgio Righetti, Soffia Magnusdottir, Cecilia Gelfi, Massimiliano Perduca

Research output: Contribution to journalArticlepeer-review


Inorganic, monovalent cations (Li, Na, K, Rb, Cs), when present in the Debye-Hückel layer of DNA, are found to bind to the negatively charged groups of the helix solely on the basis of their charge/mass ratio. Thus, when an electric field is applied, the free mobility of the DNA is seen to increase from Li- to Cs-equilibrated DNAs, since the latter cation, having a weaker surface charge distribution and a larger physical size (in the non-hydrated state), is more loosely bound to the DNA helix, thus providing less screening of its negative charges. On the contrary, organic amines (Tris and a number of Good's buffers) are found to bind not only via electrostatic interactions, but by additional bonds, notably H-bonds. In particular, Tris can form two H-bonds, with a purine and pyrimidine, respectively, and a third H-bond shared between the -OH groups of two adjacent Tris. Hence, these buffer components may be unwitting participants in reactions carried out in in vitro systems.

Original languageEnglish
Pages (from-to)309-316
Number of pages8
JournalJournal of Chromatography A
Issue number1-2
Publication statusPublished - Jun 27 2001


  • Amines
  • DNA
  • Electrophoretic mobility
  • Inorganic cations

ASJC Scopus subject areas

  • Analytical Chemistry


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