Long-distance charge transport in duplex DNA: the phonon-assisted polaron-like hopping mechanism.
An anthraquinone-linked duplex DNA oligomer containing 60 base pairs was synthesized by PCR. The strand complementary to the quinone-containing strand has four isolated GG steps, which serve as traps for a migrating radical cation. Irradiation of the quinone leads to electron transfer from the DNA to the quinone forming the anthraquinone radical anion and a base radical cation. The radical cation migrates through the DNA, causing reaction at GG steps revealed as strand breaks. The efficiency of strand cleavage falls off exponentially with distance from the quinone (slope = -0.02 A(-1)). This finding necessitates reinterpretation of mechanisms proposed for radical cation migration in DNA. We propose that radical cations form self-trapped polarons that migrate by thermally activated hopping.
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.
P T
PT
Henderson
D
D
Jones
G
G
Hampikian
Y
Y
Kan
G B
GB
Schuster
D000880:Anthraquinones / Q000138:chemical synthesis / Q000737:chemistry*; D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D004579:Electron Transport; D005609:Free Radicals / Q000737:chemistry; D007700:Kinetics; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis; D010782:Photolysis; D016133:Polymerase Chain Reaction
D000880:Anthraquinones; D005609:Free Radicals; D009838:Oligodeoxyribonucleotides; D004247:DNA