title: Molecular beacon probes of oligonucleotides photodamaged by psoralen.
abstract: Ultraviolet A (UVA)-irradiated 4'-hydroxymethyl-4,5',8-trimethyl psoralen (HMT) in the presence of a poly-dT(17) and dA(7) TTA(8) oligonucleotides produces HMT-dT(17) and HMT-dA(7) TTA(8) adducts in aqueous solution. In this article, we determine whether these HMT-dT(17) and HMT-dA(7) TTA(8) adducts can be detected with a molecular beacon (MB) probe. We measure the degree of damage in dT(17) and dA(7) TTA(8) solutions containing UVA-activated HMT via monitoring the decrease in MB fluorescence. Photoproduct formation is confirmed by MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-fight mass spectrometry measurements) and absorption spectroscopy. The MB fluorescence decreases upon UVA irradiation in the presence of HMT with a single-exponential time constants of 114.2 ± 6.5 min for HMT-dT(17) adducts and 677.8 ± 181.8 min for HMT-dA(7) TTA(8) adducts. Our results show that fluorescent MB probes are a selective, robust and accurate tool for detecting UVA-activated HMT-induced DNA damage.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, AB, Canada.
authors.forename: Zahra J
authors.initials: ZJ
authors.lastname: Shire
authors.forename: Glen R
authors.initials: GR
authors.lastname: Loppnow
mesh_terms: D018736:DNA Adducts; D005453:Fluorescence; D011564:Furocoumarins / Q000737:chemistry*; D015345:Oligonucleotide Probes; D055668:Photochemical Processes; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D018736:DNA Adducts; D011564:Furocoumarins; D015345:Oligonucleotide Probes