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Laboratoire d'Electrochimie Moleculaire, LEM, Paris

UMR CNRS - Université Paris Diderot - Paris France

   
 
Master Frontiers in Chemistry | UFR de Chimie - Université Paris Diderot - Paris 7 CNRS - Institut de chimie Université de Paris Master Chimie Sorbonne Paris Cité UFR de Chimie - Université Paris Diderot - Paris 7 CNRS - Institut de chimie
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Université Paris Diderot
Université de Paris CNRS, Centre National de la Recherche Scientifique
 
 


Le LEM - Publications: Abstracts

Publication 582

Org. Biomol. Chem., 2 (19), 2742-2750, 2004
DOI: 10.1039/b406923d
 

 


Dissociative electron transfer to and from pyrimidine cyclobutane dimers: An electrochemical study

   
Fabien Boussicault, Olivier Krüger, Marc Robert, and Uta Wille

University of Florida, Department of Chemistry, PO Box 117200, Gainesville, FL 32611-7200, USA and Université Denis Diderot-Paris 7, Laboratoire d'Electrochimie Moléculaire, UMR CNRS 7591, 2 Place Jussieu, Case courrier 7107, 75251, Paris Cedex 05, France


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.

 
 
   
 
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