title: Repair of a Dimeric Azetidine Related to the Thymine-Cytosine (6-4) Photoproduct by Electron Transfer Photoreduction.
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.
authors.affiliation: Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Consejo Superior de Investigaciones Científicas, Avda de los Naranjos, s/n, 46022, Valencia, Spain.
authors.forename: Ana B
authors.initials: AB
authors.lastname: Fraga-Timiraos
authors.affiliation: Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Consejo Superior de Investigaciones Científicas, Avda de los Naranjos, s/n, 46022, Valencia, Spain. lvirgini@itq.upv.es.
authors.forename: Virginie
authors.identifier: 0000-0002-8205-8892
authors.initials: V
authors.lastname: Lhiaubet-Vallet
authors.affiliation: Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Consejo Superior de Investigaciones Científicas, Avda de los Naranjos, s/n, 46022, Valencia, Spain. mmiranda@qim.upv.es.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Miranda
keywords: 6-azauracil; DNA damage; cycloreversion; fluorescence; photosensitization