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- Makita, Naoko, et al.
(author)
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Conformational change of giant DNA with added salt as revealed by single molecular observation
- 2006
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In: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 39:18, s. 6200-6206
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Journal article (peer-reviewed)abstract
- The structural change of individual giant double-stranded T4 DNA (165.6 kilobase pairs) molecules as a function of salt concentration was investigated by single molecular observation with fluorescence microscopy in a wide range of concentration of NaCl, 1 x 10(-6)-3 M. The measured long-axis length was transformed into a persistence length and subjected to a power-law analysis, which showed that the electrostatic contribution to the persistence length is inversely proportional to the square root of the salt concentration; i.e., it has a linear dependence on the screening length. This is interpreted as the behavior of a flexible chain with electrostatic excluded-volume interactions. Although double-stranded DNA is locally stiff, it displays flexibility when the contour length is much longer than the persistence length, as is the case for T4 DNA.
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- Rydén, Jens, et al.
(author)
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Monte Carlo simulations of oppositely charged macroions in solution
- 2005
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 123:3, s. 1-034909
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Journal article (peer-reviewed)abstract
- The structure and phase behavior of oppositely charged macroions in solution have been studied with Monte Carlo simulations using the primitive model where the macroions and small ions are described as charged hard spheres. Size and charge symmetric, size asymmetric, and charge asymmetric macroions at different electrostatic coupling strengths are considered, and the properties of the solutions have been examined using cluster size distribution functions, structure factors, and radial distribution functions. At increasing electrostatic coupling, the macroions form clusters and eventually the system displays a phase instability, in analogy to that of simple electrolyte solutions. The relation to the similar cluster formation and phase instability occurring in solutions containing oppositely charged polymers is also discussed. (c) 2005 American Institute of Physics.
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