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Model Studies of DNA Photorepair: Enthalpy of Cleavage of a Pyrimidine Dimer Measured by Photothermal Beam Deflection Calorimetry
Author(s) -
Scannell Michael P.,
Yeh SyunRu,
Falvey Daniel E.
Publication year - 1996
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1996.tb01832.x
Subject(s) - pyrimidine dimer , dimer , calorimetry , enthalpy , photothermal therapy , chemistry , dna , deflection (physics) , cleavage (geology) , photochemistry , materials science , thermodynamics , optics , dna damage , physics , nanotechnology , biochemistry , organic chemistry , composite material , fracture (geology)
— The enzyme DNA photolyase mediates the repair of pyrimidine dimers. This repair step, a net retro [ 2 +2] reaction, proceeds through either the cation or anion radical of the pyrimidine dimer. In order to understand how electron transfer makes the repair process possible, its energetics have been examined by photothermal beam deflection calorimetry, fluorescence quenching and quantum yield studies. The enthalpy for the cleavage reaction of cis‐syn 1,3‐dimethylthymine dimer itself was found to be ‐19 kcal/mol. In addition, from the redox potentials, the enthalpies for the cleavage reactions of the dimer cation radical and the anion radical were determined to be ‐19 kcal/mol and ‐28 kcal/mol, respectively.