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Study of the Affecting Factors on the Stability of G-Quadruplex Structures

Fadaei, Elham | 2017

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 49845 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Tafazzoli, Mohsen
  7. Abstract:
  8. We used spectroscopic techniques to study self-assembled structures based on nucleobases like G-quadruplexes and macrocycles. Also we used DOSY NMR technique to study hydrogen bonding network in alcohol solutions. First part of our results indicate thermodynamic stability and slow kinetic of G-quadruplexes in apolar aromatic solvents like toluene. Also our results show easy monitoring of formation of each K+ or Na+ complex by NMR, due to the low solubility of alkaline metal salts in apolar media and possibility to stop at any given time in order to control G-quadruplex yield. When combined with suitable functional units, these valuable attributes may be used for the noncovalent synthesis of self-assembled functional nanoclusters whose physical properties could be related to well-defined structures that are not altered significantly by changing environment conditions. In second part of this work, we demonstrate that resonance excitation energy transfer phenomena can be a valuable tool to unveil supplementary information about complex supramolecular processes. In particular, noncovalent macrocyclization processes of lipophilic dinucleosides are here studied by means of fluorescence emission spectroscopy by setting up a competition between intra- and intermolecular association processes. Multiwavelength analysis of the monomer emission changes allowed us to determine cyclotetramerization constants. In third part of this work, the concentration and temperature behaviors of the self-diffusion coefficient were analyzed in glycerol-water and methanol-water solutions using Diffusion-Ordered Spectroscopy (DOSY) experiment. The concentration behavior shows that there is hydrogen bond interaction between water and alcohol, which declines the self-diffusion coefficients of both in the aqueous binary mixtures. The methanol self-diffusion activation energy, in very dilute methanol-water solution (0.03 mole fraction of methanol), is consistent with the formation of iceberg-like structure which helps methanol to diffuse quickly
  9. Keywords:
  10. Self Assembly ; Nucleotides ; Fluorescence Resonance Energy Transfer ; G-Quadruplex Structures ; Diffusion-ordered NMR Spectroscopy (Dosy NMR)

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