Title page for ETD etd-01312005-145858


Type of Document Master's Thesis
Author Hurley, Jr., Eldon Kenneth
Author's Email Address hurl@vt.edu
URN etd-01312005-145858
Title Photolyase: Its Damaged DNA Substrate and Amino Acid Radical Formation During Photorepair
Degree Master of Science
Department Biochemistry
Advisory Committee
Advisor Name Title
Kim, Sunyoung Committee Chair
Bevan, David R. Committee Member
Kennelly, Peter J. Committee Member
Phillips, John B. Committee Member
Keywords
  • amino acid radical
  • thymine dimer
  • DNA repair
  • photolyase
Date of Defense 2005-01-06
Availability unrestricted
Abstract
Ultraviolet light damages genomic material by inducing the formation of covalent bonds between adjacent pyrimidines. Cis-syn cyclobutane pyrimidine dimers (CPD)constitute the most abundant primary lesion in DNA. Photolyase, a light-activated enzyme, catalytically repairs these lesions. Although many steps in the photolyase-mediated repair process have been mapped, details of the mechanism remain cryptic. Difference FT-IR spectroscopy was employed to obtain new mechanistic information about photorepair. Purified oligonucleotides, containing a central diuracil, dithymidine, or cyclobutane thymidine dimer, were monitored using vibrational methods. Construction of difference infrared data between undamaged and damaged DNA permitted examination of nucleic acid changes upon formation of the CPD lesion; these experiments indicated that C=O and C-H frequencies can be used as markers for DNA damage. Furthermore, in purified photolyase containing isotopically-labeled aromatic amino acids, we observed that tryptophan residues in photolyase underwent structural changes during photorepair. These data indicate that electron transfer during DNA repair occurs through-bond, and that redox-active, aromatic residues form the pathway for electron transfer.
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