This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Burak, Y. Articles by Andelman, D. Search for Related Content PubMed PubMed Citation Articles by Burak, Y. Articles by Andelman, D.

Onset of DNA Aggregation in Presence of Monovalent and Multivalent Counterions

School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel

Correspondence: Address reprint requests to David Andelman, School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel 69978. Tel.: 972-3-640-7239; Fax: 972-3-642-2979; E-mail: andelman{at}post.tau.ac.il.

We address theoretically aggregation of DNA segments by multivalent polyamines such as spermine and spermidine. In experiments, the aggregation occurs above a certain threshold concentration of multivalent ions. We demonstrate that the dependence of this threshold on the concentration of DNA has a simple form. When the DNA concentration c_DNA is smaller than the monovalent salt concentration, the threshold multivalent ion concentration depends linearly on c_DNA, having the form c_DNA + ß. The coefficients and ß are related to the density profile of multivalent counterions around isolated DNA chains, at the onset of their aggregation. This analysis agrees extremely well with recent detailed measurements on DNA aggregation in the presence of spermine. From the fit to the experimental data, the number of condensed multivalent counterions per DNA chain can be deduced. A few other conclusions can then be reached: 1), the number of condensed spermine ions at the onset of aggregation decreases with the addition of monovalent salt; 2), the Poisson-Boltzmann theory overestimates the number of condensed multivalent ions at high monovalent salt concentrations; and 3), our analysis of the data indicates that the DNA charge is not overcompensated by spermine at the onset of aggregation.

This article has been cited by other articles:

				K. Andresen, X. Qiu, S. A. Pabit, J. S. Lamb, H. Y. Park, L. W. Kwok, and L. Pollack Mono- and Trivalent Ions around DNA: A Small-Angle Scattering Study of Competition and Interactions Biophys. J., July 1, 2008; 95(1): 287 - 295. [Abstract] [Full Text] [PDF]

				C. Douarche, J.-L. Sikorav, and A. Goldar Aggregation and Adsorption at the Air-Water Interface of Bacteriophage {phi}X174 Single-Stranded DNA Biophys. J., January 1, 2008; 94(1): 134 - 146. [Abstract] [Full Text] [PDF]

				V. B. Teif Ligand-Induced DNA Condensation: Choosing the Model Biophys. J., October 1, 2005; 89(4): 2574 - 2587. [Abstract] [Full Text] [PDF]

				I. Borukhov, R. F. Bruinsma, W. M. Gelbart, and A. J. Liu Structural polymorphism of the cytoskeleton: A model of linker-assisted filament aggregation PNAS, March 8, 2005; 102(10): 3673 - 3678. [Abstract] [Full Text] [PDF]

				E. Raspaud, D. Durand, and F. Livolant Interhelical Spacing in Liquid Crystalline Spermine and Spermidine-DNA Precipitates Biophys. J., January 1, 2005; 88(1): 392 - 403. [Abstract] [Full Text] [PDF]