Dependence of the internal relaxation time for DNA on salt type as inferred by quasielastic light scattering
✍ Scribed by Nambi Parthasarathy; Kenneth S. Schmitz
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1980
- Tongue
- English
- Weight
- 636 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Quasielastic light scattering methods were used to study calf thymus DNA in solutions of LiCl, NaCl, NHdAc, and NH4Cl. Plots of the reciprocal relaxation time (1/7) vs sinz(O/2), where 6 is the scattering angle, exhibit two linear regions, in accordance with theories for semiflexible polymers based on the t -0 approximation. In these theories the slope of the linear region a t low angles is associated with the translational diffusion coefficient ( D t ) , whereas the slope of the linear region at high angles is associated with the segmental diffusion coefficient (D, = kT/js). The midpoint of the "transition" between these two linear regions is associated with the mean displacement between segments (b). Data presented hereindicate that the Rouse-Zimm parameters b and fs are significantly different for DNA in 0.4M NH&1 relative to the other salts a t comparable ionic strengths. It is suggested that this difference reflects local solvent structure and that both b and D, are sensitive to the local water structure.