Repair of a Dimeric Azetidine Related to the Thymine–Cytosine (6‐4) Photoproduct by Electron Transfer Photoreduction |
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Authors: | Ana B Fraga‐Timiraos Dr Virginie Lhiaubet‐Vallet Prof Miguel A Miranda |
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Institution: | Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Consejo Superior de Investigaciones Científicas, Valencia, Spain |
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Abstract: | Photolyases are intriguing enzymes that take advantage of sunlight to restore lesions like cyclobutane pyrimidine dimers or (6‐4) photoproducts. This work focused on the photoreductive process responsible for splitting of the azetidine ring proposed to occur during (6‐4) photoproduct repair at a thymine–cytosine sequence. A model compound formed by photocycloaddition between thymine and 6‐azauracil has been designed to mimic the elusive azetidine intermediate. The photoinduced electron transfer process has been investigated by means of steady‐state and time‐resolved fluorescence using photosensitizers with oxidation potentials in the singlet excited state ranging from ?3.3 to ?2.1 V vs. SCE. Azetidine ring splitting and recovery of “repaired” bases were proven by HPLC analysis. |
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Keywords: | 6-azauracil cycloreversion DNA damage fluorescence photosensitization |
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