Roles
Student Author:
Abby Bull '16, Gettysburg College
Document Type
Article
Publication Date
5-15-2020
Department 1
Physics
Abstract
Quantitative understanding of biomolecular electrostatics, particularly involving multivalent ions and highly charged surfaces, remains lacking. Ion-modulated interactions between nucleic acids provide a model system in which electrostatics plays a dominant role. Using ordered DNA arrays neutralized by spherical cobalt3+ hexammine and Mg2+ ions, we investigate how the interstitial ions modulate DNA-DNA interactions. Using methods of ion counting, osmotic stress, and x-ray diffraction, we systematically determine thermodynamic quantities, including ion chemical potentials, ion partition, DNA osmotic pressure and force, and DNA-DNA spacing. Analyses of the multidimensional data provide quantitative insights into their interdependencies. The key finding of this study is that DNA-DNA forces are observed to linearly depend on the partition of interstitial ions, suggesting the dominant role of ion-DNA coupling. Further implications are discussed in light of physical theories of electrostatic interactions and like-charge attraction.
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
DOI
10.1016/j.bpj.2020.05.001
Version
Post Print
Recommended Citation
Meng, Wei, Raju Timsina, Abby Bull, Kurt Andresen, and Xiangyun Qiu. “Additive Modulation of DNA-DNA Interactions by Interstitial Ions.” Biophysical Journal 118, no. 12 (June 16, 2020): 3019–25.
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This article is also available from the publisher’s website.
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