Thymine dimer splitting in the T<>T-G trinucleotide model system: A semiclassical dynamics and TD-DFT study

The mechanism leading to bond cleavage of a thymine–thymine cyclobutane dimer (T<>T) in a model system consisting of the dimer flanked by guanine trinucleotide was studied using semiclassical dynamics simulation. Pulsed laser excitation of the guanine molecule is found to cause electron transfer from the guanine molecule to the dimer, which then dissociates via sequential cleavage of the C5C5′ and C6C6′ bonds. Subsequently, electrons transfer back to the guanine molecule as the dimer splits into two monomers. The splitting of the cyclobutane dimer was found to be in the femtosecond time scale.

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