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Repair of a Dimeric Azetidine Related to the Thymine–Cytosine (6 ‐ 4) Photoproduct by Electron Transfer Photoreduction
Author(s) -
FragaTimiraos Ana B.,
LhiaubetVallet Virginie,
Miranda Miguel A.
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201601475
Subject(s) - azetidine , pyrimidine dimer , thymine , photolyase , photochemistry , chemistry , cyclobutane , cytosine , singlet state , electron transfer , photoinduced electron transfer , fluorescence , pyrimidine , dna , excited state , stereochemistry , ring (chemistry) , dna damage , dna repair , biochemistry , organic chemistry , physics , quantum mechanics , nuclear physics
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.