Parts | Days | Selection | Search | Downloads | Help
MO: Molekülphysik
MO 45: Biomolecules II
MO 45.4: Talk
Wednesday, March 15, 2006, 17:15–17:30, H10
Thymine dimer formation probed by femtosecond infrared spectroscopy — •Wolfgang Schreier1, Tobias Schrader1, Florian Koller1, Peter Gilch1, Wolfgang Zinth1, and Bern Kohler2 — 1Ludwig-Maximilians-Universität, Department of Physics, Chair for BioMolecular Optics, Oettingenstr. 67, 80538 München — 2The Ohio State University, Department of Chemistry, 100 West 18th Avenue, Columbus, Ohio 43210
Absorption of UV radiation by DNA bases is known to induce harmful mutagenic products. One major photoproduct at bipyrimidine sites is the photodimerization of neighboring thymine residues. Despite the intense work in this field there is still a lack of information regarding the time scale at which these dimers are formed [1], [2].
We used time resolved UV pump, IR probe spectroscopy to investigate the 18-mer of single-stranded thymidylic acid [(dT)18] and the corresponding mononucleotide (thymidine monophosphate, TMP). We show that femtosecond infrared spectroscopy can address dimer specific marker bands between 1300 and 1500 cm−1 and that the excitation of the oligonucleotide leads to the formation of cyclobutane dimers in less than 20 ps. Additionally we find no slow growth in these marker bands as expected for a triplet intermediate. This points to a singlet precursor for these photoproducts.
[1] Crespo-Hernandez CE, Cohen B, Kohler B, NATURE 436 (7054): 1141-1144 (2005)
[2] Marguet S, Markovitsi D, JACS 127 (16): 5780-5781 (2005)