I. RNA A-to-Z transitions and DNA B-to-Z transitions. II. Circular intensity differential scattering of cholesteric liquid crystals
The thesis is composed of two parts: Part I describes the conformational transitions of DNA and RNA from right-handed helices to left-handed helices. These transitions, referred to as B-to-Z for DNA and A-to-Z for RNA, are effected by specific solvents and temperatures. Various spectroscopic methods show the details of the transition, with near ultraviolet circular dichroism (CD) indicating the differences in the transition moments between the DNA and RNA, and nuclear magnetic resonance (NMR) and vacuum ultraviolet CD indicating that the structures are very similar. Thermodynamic parameters for the DNA polymer transition are calculated, indicating that the transition is not isoenthalpic as previously postulated. A tetramer of RNA, rCGCG, is used for obtaining thermodynamic data on the RNA A-to-Z transition. This short sequence also appears to adopt a left-handed structure, but thermodynamic data indicates that the A-form is more favorable. Part II describes the circular differential scattering (CIDS) of cholesteric liquid crystals. These compounds have a natural helical order, with enormous scattering power. The scattering patterns obtained from the liquid crystals are influenced by the helical parameters such as pitch and handedness, as predicted by the theory. It is hoped that these model compounds will provide information for the interpretation of the CIDS spectra obtained for biological samples, such as gels of DNA or oriented viruses.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5976081
- Report Number(s):
- LBL-18887; ON: DE85007660
- Resource Relation:
- Other Information: Portions are illegible in microfiche products. Thesis
- Country of Publication:
- United States
- Language:
- English
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