Anomalous Salt Effects on DNA Conformation:  Experiment and Theory

The condensation of a single DNA can be induced by multivalent counterions and is thought to be due to ion−ion correlations. Both Monte Carlo simulations and fluorescence microscopy experiments confirm this picture. The effect is less pronounced for chain counterions (polyamines) than for simple sph...

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Bibliographic Details
Published in:Macromolecules 1999-12, Vol.32 (26), p.8836-8840
Main Authors: Khan, Malek O, Mel'nikov, Sergey M, Jönsson, Bo
Format: Article
Language:English
Subjects:
Amines
Applied sciences
Biological and medical sciences
Computer simulation
Condensation
Conformations
Correlation methods
Exact sciences and technology
Fluorescence
Fundamental and applied biological sciences. Psychology
In solution. Condensed state. Thin layers
Miscellaneous
Molecular biophysics
Monte Carlo methods
Natural polymers
Optical microscopy
Physico-chemical properties of biomolecules
Physicochemistry of polymers
Salts
Thermal effects
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Summary:The condensation of a single DNA can be induced by multivalent counterions and is thought to be due to ion−ion correlations. Both Monte Carlo simulations and fluorescence microscopy experiments confirm this picture. The effect is less pronounced for chain counterions (polyamines) than for simple spherical counterions with the same charge. When simple salt is added to the system, the polyelectrolyte unfolds. MC simulations show that this is due to a competition between the different small ion species. The multivalent ions in the vicinity of the macroion are exchanged for univalent ones, decreasing the effect of ion−ion correlations. It is also found that the temperature effect on the macroion conformation is quite insignificant in the studied interval (5.0−65.0 °C).
ISSN:0024-9297
1520-5835
DOI:10.1021/ma9905627