Molecular dynamics studies of ion distributions for DNA duplexes and DNA clusters: Salt effects and connection to DNA melting

Hai Long, Alexander Kudlay, George C. Schatz

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68 Citations (Scopus)


We present extensive molecular dynamics simulations of the ion distributions for DNA duplexes and DNA clusters using the Amber force field with implicit water. The distribution of ions and the electrostatic energy of ions around an isolated DNA duplex and clusters of DNA duplexes in different salt (NaCl) concentrations over the range 0.2-1.0 mol/L are determined on the basis of the simulation results. Using the electrostatic energy profile, we determine a local net charge fraction φ, which is found to increase with increasing of salt concentration. For DNA clusters containing two DNA duplexes (DNA pair) or four DNA duplexes, φ increases as the distance between the duplexes decreases. Combining this result with experimental results for the dependence of the DNA melting temperature on bulk salt concentration, we conclude that for a pair of DNA duplexes the melting temperature increases by 5-10 K for interaxis separations of 25-40 Å. For a cluster of four DNA duplexes, an even larger melting temperature increase should occur. We argue that this melting temperature increase in dense DNA clusters is responsible for the cooperative melting mechanism in DNA-linked nanoparticle aggregates and DNA-linked polymer aggregates.

Original languageEnglish
Pages (from-to)2918-2926
Number of pages9
JournalJournal of Physical Chemistry B
Issue number6
Publication statusPublished - Feb 16 2006


ASJC Scopus subject areas

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

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