7025-74-3Relevant articles and documents
Model studies of DNA photorepair: Enthalpy of cleavage of a pyrimidine dimer measured by photothermal beam deflection calorimetry
Scannell,Yeh,Falvey
, p. 764 - 768 (1996)
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 he -19 kcal/mol and -28 kcal/mol, respectively.
Dissociative electron transfer to and from pyrimidine cyclobutane dimers: an electrochemical study.
Boussicault, Fabien,Krueger, Oliver,Robert, Marc,Wille, Uta
, p. 2742 - 2750 (2007/10/03)
Cyclic voltammetry was used to study the reduction and oxidation behaviour of several pyrimidine cyclobutane dimers mimicking UV induced lesion in DNA strands in polar solvents (N,N-dimethylformamide and acetonitrile). Both electron injection and removal to and from the dimers, respectively, lead to their cleavage and reformation of the monomeric base. The influence of stereochemistry and substitution pattern at the cyclobutane motif on the reactivity has been studied. It appears that the repair process always proceeds in a sequential fashion with initial formation of a dimer ion radical intermediate, which then undergoes ring opening by homolytic cleavage of the two C-C bonds. Standard redox potentials for the formation of both radical anion and radical cation state of the dimers were determined. Quantum calculations on simplified model compounds reveal the reason for the finding that the exergonic homolytic cleavages of the carbon-carbon bonds are endowed with sizeable activation barriers. The consequences of these mechanistic studies on the natural enzymatic repair by photolyase enzyme are discussed. Copyright 2004 The Royal Society of Chemistry
The inhibition of the photochemical dimerization of 1,3-dimethylthymine by flavin and 5-deazaflavin derivatives.
Tanaka,Kawase,Okuno,Senda,Kimachi,Yoneda
, p. 2265 - 2267 (2007/10/02)
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