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Thermochemical Properties of Thymine & Deoxythymidine

Shakorian Fard, Mehdi | 2008

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39127 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Fattahi, Alireza
  7. Abstract:
  8. Nowadays, there is no doubt about the importance of investigation of physicochemical properties of nucleosides in order to determine the structure of these biopolymers. Nucleotides have a variety of roles in cellular metabolism. They are the constituents of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the molecular repositories of genetic information. The metal ions play a significant role in several biological processes. Synthesis, replication, and cleavage of DNA and RNA as well as their structure integrity are affected by the presence of these ionized metals in the cell nucleus. To understand the role of cations in the biophysics of DNA, it is necessary first to carry out a detailed interaction study of ions with isolated base and nucleosides. Whether and where a specific metal ion will interact with a nucleic acid is controlled, at least in part, by the relative bond strength between the metal ion and the possible donor group present in the nucleic acid chain. Knowledge about the fundamental modes of metal ion binding to simple DNA and RNA components (nucleobases, nucleosides, etc) would greatly improve our understanding on how metal ions interact with more complex nucleic acid structure. In this study, we have carried out a detailed study on the coordination modes, geometrical structures and binding energies of the complexes formed by coordination of Li+, Na+, K+, Cu+, Mg2+, Ca2+ and Zn2+ cations and some biologically important anions such as F-, Cl- and CN- with Thymine and Deoxythymidine. The results show that there are two sites, O2 and O4, in thymine for complexation. In deoxythymidine complexes with cations such as Cu+, Mg2+, Ca2+ and Zn2+, there are the same sites for complexation, but these sites are different for Li+, Na+, and K+ in complexation. In a group of Periodic Table, the metal ion affinity decreases by increasing the atomic number of metal and anions as well as cations can be coordinated to these molecules. Calculations were carried out using B3LYP/6-311++G** level of theory in the gas- phase using Spartan and Gaussian 98 software
  9. Keywords:
  10. Thymine ; Metal Ion Affinity ; Anion Affinity ; Density Functional Theory (DFT) ; Deoxythymidine

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