Abstract
The presence of small numbers of multivalent ions in DNA-containing solutions results in strong attractive forces between DNA strands. Despite the biological importance of this interaction, e.g., DNA condensation, its physical origin remains elusive. We carried out a series of experiments to probe interactions between short DNA strands as small numbers of trivalent ions are included in a solution containing DNA and monovalent ions. Using resonant (anomalous) and nonresonant small angle x-ray scattering, we coordinated measurements of the number and distribution of each ion species around the DNA with the onset of attractive forces between DNA strands. DNA-DNA interactions occur as the number of trivalent ions increases. Surprisingly good agreement is found between data and size-corrected numerical Poisson-Boltzmann predictions of ion competition for non- and weakly interacting DNAs. We also obtained an estimate for the minimum number of trivalent ions needed to initiate DNA-DNA attraction.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 287-295 |
| Number of pages | 9 |
| Journal | Biophysical journal |
| Volume | 95 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jul 1 2008 |
| Externally published | Yes |
Bibliographical note
Funding Information:This research is funded by the National Science Foundation through grant No. MCB-0347220, and The Nanobiotechnology Center at Cornell. Additional support was provided by the National Institutes of Health through grant No. P01-GM066275. CHESS is supported by the National Science Foundation and the National Institutes of Health/National Institute of General Medical Sciences under grant No. DMR-9713424. The Cornell NanoScale Science & Technology Facility is supported by the National Science Foundation, Cornell University, and industrial affiliates.