The study deals with the primary species, ejected electrons, and guanine radicals, leading to oxidative damage, that is generated in four-stranded DNA structures (guanine quadruplexes) following photo-ionization by low-energy UV radiation. Performed by nanosecond transient absorption spectroscopy with 266 nm excitation, it focusses on quadruplexes formed by folding of GGG(TTAGGG) single strands in the presence of K ions, . The quantum yield for one-photon ionization (9.4 × 10) was found to be twice as high as that reported previously for . The overall population of guanine radicals decayed faster, their half times being, respectively, 1.4 and 6.7 ms. Deprotonation of radical cations extended over four orders of magnitude of time; the faster step, concerning 40% of their population, was completed within 500 ns. A reaction intermediate, issued from radicals, whose absorption spectrum peaked around 390 nm, was detected.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7248781 | PMC |
| http://dx.doi.org/10.3390/molecules25092094 | DOI Listing |
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