Time-resolved study of thymine dimer formation

Sylvie Marguet (1) , Dimitra Markovitsi (1)

1 LFP - URA 2453 - Laboratoire Francis PERRIN

The formation of thymine dimers in the single-stranded oligonucleotide, (dT)20, is studied at room temperature by laser flash photolysis using 266 nm excitation. It is shown that the (6-4) adduct is formed within 4 ms via a reactive intermediate. The formation of cyclobutane dimers is faster than 200 ns. The overall quantum yield for the (6-4) formation is (3.7 ± 0.3) × 10-3, and that of the cyclobutane dimers is (2.8 ± 0.2) × 10-2. No triplet absorption is detected, showing that either the intersystem crossing yield decreases by 1 order of magnitude upon oligomerization (<1.4 × 10-3) or the triplet state reacts with unit efficiency in less than 200 ns to yield cyclobutane dimers.

Domaines: Chimie théorique et/ou physique

Sylvie Marguet, Dimitra Markovitsi. Time-resolved study of thymine dimer formation. Journal of the American Chemical Society, 2005, 127, pp.5780-5781. ⟨10.1021/ja050648h⟩. ⟨hal-00083445⟩