In the first part of the chapter, emphasis is placed on the description of the main reactions of radical cations of the four predominant DNA purine and pyrimidine bases and minor 5-methylcytosine in aerated aqueous solutions. Information is also provided on the final one-electron oxidation products of 8-oxo-7,8-dihydroguanine, an ubiquitous decomposition product of DNA with most chemical and physical...
Hole injection Hole injection into a guanine of DNA, and hole transfer hole transfer between the DNA guanines were studied. The reactions were performed in the ground state using a carbohydrate radical cation whose precursor is site-selectively incorporated into the DNA. For the charge injection step the influence of the distance, the energy difference of donor and acceptor, and the bridge were...
The dynamics of single step hole transport processes from a guanine cation radical (G+·) to GG, GGG and deazaguanine (Z) secondary electron donors separated by one or two A:T base pairs have been investigated by means of nanosecond time-resolved absorption spectroscopy with kinetic modeling. Photoinduced electron transfer from G to a stilbenedicarboxamide (Sa) hairpin linker is used to generate a...
A range of photophysical and biochemical experiments have been conducted to establish DNA charge transport, to probe those parameters that influence DNA-mediated charge transport, and to explore the biological applications and consequences. Charge migration through the DNA base stack has been shown to result in oxidative damage 200 Å from the site of the remotely-bound oxidant, but this long-range...
Hole transfer in DNA has attracted much interest, since the hole causes oxidative damage in vivo which leads to mutation. Furthermore, the occurrence of long-range hole transfer in DNA suggests a potential application of DNA as a building block for biosensors and bioelectronic devices. DNA is an attractive molecule to connect two points selected according to the information of DNA carried as the base...
The irradiation of an anthraquinone derivative that is covalently attached to duplex DNA injects a radical cation into the bases of the DNA. This radical cation can migrate hundreds of Ångstroms before it is trapped at GG steps by reaction with water. These damaged guanines result in DNA strand scissions when they are treated with piperidine. Investigation of several such DNA constructs reveals that...
The transfer of positive charge through DNA has been investigated in great detail over the last couple of years. In this area, major new mechanistic insights have been gained using defined acceptor modified DNA strands. Transport of exon electrons, in contrast, is much less well-explored. Our current mechanistic understanding is based on EPR spectroscopic studies of DNA material reduced using solvated...