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Photochem Photobiol. 2012 May-Jun;88(3):645-50. doi: 10.1111/j.1751-1097.2012.01109.x. Epub 2012 Mar 8.

Molecular beacon probes of oligonucleotides photodamaged by psoralen.

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1
Department of Chemistry, University of Alberta, Edmonton, AB, Canada.

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.

[Indexed for MEDLINE]

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