051: Фізико-математичні науки

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The effect of triplet-triplet excitation energy transfer on the DNA self-protection mechanism
(2006) Yashchuk, V.; Kudrya, V.; Dubey, Igor; Losytskyy, M.; Ohulchanskyy, Tymish; Suga, H.; Yarmoluk, S.
The displacement of the DNA electronic energy levels, triplet electronic excitation energy transfer and their relation to the DNA damage under UV-irradiation were investigated by electronic absorption and phosphorescence studies. The lowest excited electronic triplet levels of the DNA (as well as the highest singlet levels) were shown to be related with adenine bases. However the AT-sequences are main traps for triplet excitation in the DNA and the DNA phosphorescence is connected namely with these traps. It was supposed that mobile triplet excitations in the DNA could spread on the distance of about 16 base pairs. According to the obtained results, main part of the triplet excitations in the DNA is finally localized on the photostable traps associated with AT-sequences. Thus, the hierarchy of the DNA bases electronic levels positions favors the triplet electronic excitation energy transfer process that leads to inhibition of photochemical destruction of the DNA. It was shown by the investigation of the DNA and base model compounds photodamage induced by UV-irradiation. The latter proves the existence of the DNA self-protection mechanism against damage of p-electronic systems of this macromolecule (caused by their excitations of different origins).