Magnetic birefringence study of the electrostatic and intrinsic persistence length of DNA

✍ Scribed by G. Maret; G. Weill

• Publisher: Wiley (John Wiley & Sons)
• Year: 1983
• Tongue: English
• Weight: 1016 KB
• Volume: 22
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360221215

✦ Synopsis

Magnetic birefringence experiments were performed on solutions of DNA of intermediate molecular weight at several concentrations (c,) over a wide range of ionic strengths (of NaCl and MgC12). The specific Cotton-Mouton constant (CMIc,) is found to be independent of cp when contributions from cp to the ionic strength (peff) are taken into account according to the concept of counterion condensation. For p e f f t 10-2M, CMIc, is also independent of the ionic strength the plateau value results in an acceptable value of the intrinsic persistence length, when a revised theoretical expression for the magnetic birefringence of wormlike chains is used, combined with new experimental data for the monomeric optical and magnetic anisotropy. For peff < 10-2M, CMIc, strongly, or weakly, increases with decreasing jieff, depending on the valency of the counterion used (Na+ or Mg2+, respectively). This increase agrees quantitatively with the variation of the electrostatic persistence length as predicted by Odijk [(1977)