One-electron Oxidation of a Pyrenyl Photosensitizer Covalently Attached to DNA and Competition Between its Further Oxidation and DNA Hole Injection
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Author(s)
Yun, Byeong Hwa
Dedon, Peter C.
Geacintov, Nicholas E.
Shafirovich, Vladimir
Date Issued
April 2010
Journal
Photochemistry and Photobiology
Publisher
Wiley Blackwell
Citation
Yun, Byeong Hwa, Peter C. Dedon, Nicholas E. Geacintov, and Vladimir Shafirovich. “One-Electron Oxidation of a Pyrenyl Photosensitizer Covalently Attached to DNA and Competition Between Its Further Oxidation and DNA Hole Injection.” Photochemistry and Photobiology 86, no. 3 (January 22, 2010): 563–570.
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Author's final manuscript
Abstract
The photosensitized hole injection and guanine base damage phenomena have been investigated in the DNA sequence, 5′-d(CATG[subscript 1] [superscript Py]CG[subscript 2]TCCTAC) with a site-specifically positioned pyrene-like (Py) benzo[a]pyrene 7,8-diol 9,10-epoxide-derived N[superscript 2]-guanine adduct (G[subscript 1] [superscript Py]). Generation of the Py radical cation and subsequent hole injection into the DNA strand by a 355 nm nanosecond laser pulses (∼4 mJ cm[superscript −2]) results in the transformation of G[subscript 1] [superscript Py] to the imidazolone derivative Iz[subscript 1] [superscript Py] and a novel G[subscript 1] [superscript Py*] photoproduct that has a mass larger by 16 Da (M+16) than the mass (M) of G[subscript 1] [superscript Py]. In addition, hole transfer and the irreversible oxidation of G[subscript 2], followed by the formation of Iz[subscript 2] was observed (Yun et al. [2007], J. Am. Chem. Soc., 129, 9321). Oxygen-18 and deuterium isotope labeling methods, in combination with an extensive analysis of the MS/MS fragmentation patterns of the individual dG[superscript Py*] nucleoside adduct and other data show that dG[superscript Py*] has an unusual structure with a ruptured cyclohexenyl ring with a carbonyl group at the rupture site and intact guanine and pyrenyl residues. The formation of this product competes with hole injection and thus diminishes the efficiency of oxidation of guanines within the oligonucleotide strand by at least 15% in comparison with that in the dG[superscript Py] nucleoside adduct.
MIT Department
Massachusetts Institute of Technology. Department of Biological Engineering
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DOI of Published Version
https://doi.org/10.1111/j.1751-1097.2010.00719.x
