Linear dichroism studies of nucleic acids. III. Reduced dichoism curves of DNA in ethanol–water and in poly(vinyl alcohol) films
✍ Scribed by Yukio Matsuoka; Bengt Nordén
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1983
- Tongue
- English
- Weight
- 737 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
The uv linear dichroism of calf thymus DNA has been studied a t different degrees of orientation both in flow-oriented ethanol-water solutions and in a stretched aqueous host of poly(viny1 alcohol) (PVA). The reduced dichroism (LDR) curves in the region 250-290 nm for DNA in PVA films at 75 and 100% relative humidity (r. h.) are in fair agreement with the curves calculated for the A-and B-forms of DNA, based on the fiber structures and the K-X* transitions of the free bases. This suggests that DNA adopts its A and B conformations in PVA at 75 and 100% r. h. In ethanol, on the other hand, a deviation from the A-form spectrum shows that the conformation of DNA in the solution can differ from the fiber structure. A t shorter wavelengths, a positive contribution to LDR is explained in terms of an out-of-plane polarized n-r* transition.