UV-Induced Charge-Transfer States in Short Guanosine-Containing DNA Oligonucleotides.

ABSTRACT: Charge transfer has proven to be an important mechanism in DNA photochemistry. In particular, guanine (dG) plays a major role as an electron donor, but the photophysical dynamics of dG-containing charge-transfer states have not been extensively investigated so far. Here, we use UV pump (266?nm) and picosecond IR probe (?5-7??m) spectroscopy to study ultrafast dynamics in dG-containing short oligonucleotides as a function of sequence and length. For the pure purine oligomers, we observed lifetimes for the charge-transfer states of the order of several hundreds of picoseconds, regardless of the oligonucleotide length. In contrast, pyrimidine-containing dinucleotides d(GT) and d(GC) show much faster relaxation dynamics in the 10 to 30?ps range. In all studied nucleotides, the charge-transfer states are formed with an efficiency of the order of ?50?%. These photophysical characteristics will lead to an improved understanding of DNA damage and repair processes.

SUBMITTER: Kufner CL 

PROVIDER: S-EPMC7496882 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature