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RESEARCH PRODUCT
On the Intrinsically Low Quantum Yields of Pyrimidine DNA Photodamages: Evaluating the Reactivity of the Corresponding Minimum Energy Crossing Points
Angelo GiussaniGraham A. Worthsubject
PyrimidineUltraviolet RaysQuantum yieldPyrimidine dimer010402 general chemistryPhotochemistry01 natural sciencesNucleobaseAdductCyclobutanechemistry.chemical_compound0103 physical sciencesComputer SimulationGeneral Materials SciencePhysical and Theoretical Chemistry010304 chemical physicsChemistryDNAConical intersectionPhotochemical Processes0104 chemical sciences3. Good healthThymineEstructura químicaPyrimidine DimersFisicoquímicadescription
The low quantum yield of photoformation of cyclobutane pyrimidine dimers and pyrimidine-pyrimidone (6-4) adducts in DNA bases is usually associated with the presence of more favorable nonreactive decay paths and with the unlikeliness of exciting the system in a favorable conformation. Here, we prove that the ability of the reactive conical intersection to bring the system either back to the absorbing conformation or to the photoproduct must be considered as a fundamental factor in the low quantum yields of the mentioned photodamage. In support of the proposed model, the one order of magnitude difference in the quantum yield of formation of the cyclobutane thymine dimer with respect to the thymine-thymine (6-4) adduct is rationalized here by comparing the reactive ability of the seam of intersections leading respectively to the cyclobutane thymine dimer and the oxetane precursor of the thymine-thymine (6-4) adduct at the CASPT2 level of theory.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2020-06-04 |