Long-range charge transport through double-stranded DNA mediated by manganese or iron porphyrins.
Guanine oxidation by electron transfer results in the formation of a guanine radical cation, which is at the origin of long-range charge transport through double-stranded DNA. It is possible to observe guanine lesions at a long distance from the oxidative reagent covalently bound to DNA owing to the migration of the positive hole in the DNA pi-stacks. This phenomenon of long-range hole transport is classically studied in the literature with photosensitizers used as one-electron oxidants. It is shown in the present work that the process of long-range charge transport and the concomitant formation of guanine lesions at a long distance can be observed also in the case of two-electron oxidants. This is the signature of the formation of a transient guanine radical cation in the course of the two-electron abstraction process and consequently evidence of the separated one plus one electron abstraction steps. Long-range charge transport is likely to be a universal mechanism for any two-electron oxidant acting by electron abstraction provided that the second electron abstraction is slower than hole transfer.
Makarska
Magdalena
M
Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse Cedex 4, France.
Pratviel
Geneviève
G
D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D004579:Electron Transport; D005290:Ferric Compounds / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry; D008345:Manganese / Q000737:chemistry*; D008665:Metalloporphyrins / Q000737:chemistry*; D015394:Molecular Structure; D009841:Oligonucleotides / Q000737:chemistry; D010084:Oxidation-Reduction
D005290:Ferric Compounds; D008665:Metalloporphyrins; D009841:Oligonucleotides; D008345:Manganese; D006147:Guanine; D004247:DNA