DNA Intercalated Psoralen Undergoes Efficient Photoinduced Electron Transfer.
The interaction of psoralens with DNA has been used for therapeutic and research purposes for decades. Still the photoinduced behavior of psoralens in DNA has never been observed directly. Femtosecond transient absorption spectroscopy is used here to gain direct insight into the photophysics of a DNA-intercalated psoralen (4'-aminomethyl-4,5',8-trimethyl-psoralen (AMT)). Intercalation reduces the excited singlet lifetime of AMT to 4 ps compared with 1400 ps for AMT in water. This singlet quenching prohibits the population of the triplet state that is accessed in free AMT. Instead, a DNA to AMT electron transfer takes place. The resulting radical pair decays primarily via charge recombination with a time constant of 30 ps. The efficient electron transfer observed here reveals a completely new aspect of the psoralen-DNA interaction.
Institut für Physikalische Chemie, Heinrich Heine Universität, Gebäude 25.43.01, Universitätstrasse 1, 40225 Düsseldorf, Germany.
Sascha
S
Fröbel
Institut für Physikalische Chemie, Heinrich Heine Universität, Gebäude 25.43.01, Universitätstrasse 1, 40225 Düsseldorf, Germany.
Anna
A
Reiffers
Institut für Physikalische Chemie, Heinrich Heine Universität, Gebäude 25.43.01, Universitätstrasse 1, 40225 Düsseldorf, Germany.
Christian
C
Torres Ziegenbein
Institut für Physikalische Chemie, Heinrich Heine Universität, Gebäude 25.43.01, Universitätstrasse 1, 40225 Düsseldorf, Germany.
Peter
P
Gilch
D004247:DNA / Q000737:chemistry*; D004579:Electron Transport; D005363:Ficusin / Q000737:chemistry*; D007364:Intercalating Agents / Q000737:chemistry*; D010777:Photochemistry; D013057:Spectrum Analysis
D007364:Intercalating Agents; D004247:DNA; D005363:Ficusin
DNA intercalation; PUVA therapy; femtosecond spectroscopy; kinetics; photochemical reaction; photoinduced electron transfer; psoralen