Conformation of LiDNA in solutions of LiCl

✍ Scribed by Nina Borochov; Henryk Eisenberg

• Publisher: Wiley (John Wiley & Sons)
• Year: 1984
• Tongue: English
• Weight: 614 KB
• Volume: 23
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360230910

✦ Synopsis

We have derived radii of gyration, R,, from the absolute intensity of the scattered light of monodisperse linear Col E, LiDNA in solution at various LiCl concentrations up to 5M. The second virial coefficients, A , , decrease strongly with increasing LiCl concentration, and vanish between 3 and 5M LiCl. It was thus possible to calculate a limiting value a t a high salt concentration of 28.5 nm for the persistence length, a,,, of' LiDNA, without the necessity of applying excluded-volume corrections. The value obtained is in good agreement with the value previously obtained for NaDNA a t high NaCl concentrations, and can be identified with the high salt limit of DNA flexibility, with long-range electrostatic interactions effectively screened. Sedimentation coefficients in the ultracentrifuge and apparent and translational diffusion coefficients (at finite and vanishing scattering vectors, respectively) from dynamic laser-light scattering have also been obtained up to 5MLiCI. From the sedimentation and apparent diffusion, D(901, (at 90" scattering angle only) above 5M, and up to 9M LiC1, it could be shown that the solutions a r e stable for reasonable periods of time, and the molecular parameters vary smoothly and moderately a t high salt. Conformational transitions were not observed and precipitation occurs between 9 and 10M LiCI.