DNA oxidation in anionic reverse micelles: ruthenium-mediated damage at Guanine in single- and double-stranded DNA.
One-electron guanine oxidation in DNA has been investigated in anionic reverse micelles (RMs). A photochemical method for generating Ru3+ from the ruthenium polypyridyl complex tris(2-2'-bipyridine)ruthenium(II) chloride ([Ru(bpy)3]Cl2) is combined with high-resolution polyacrylamide gel electrophoresis (PAGE) to quantify piperidine-labile guanine oxidation products. As characterized by emission spectroscopy of Ru(bpy)3(2+), the addition of DNA to RMs containing Ru(bpy)3(2+) does not perturb the environment of Ru(bpy)3(2+). The steady-state quenching efficiency of Ru(bpy)3(2+) with K3[Fe(CN)6] in buffer solution is approximately 2-fold higher than that observed in RMs. Consistent with the difference in quenching efficiency in the two media, a 1.5-fold higher yield of piperidine-labile damage products as monitored by PAGE is observed for duplex oligonucleotide in buffer vs RMs. In contrast, a 13-fold difference in the yield of PAGE-detected G oxidation products is observed when single-stranded DNA is the substrate. Circular dichroism spectra showed that single-stranded DNA undergoes a structural change in anionic RMs. This structural change is potentially due to cation-mediated adsorption of the DNA phosphates on the anionic headgroups of the RMs, leading to protection of the guanine from oxidatively generated damage.
Department of Chemistry & Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, USA.
Sarah E
SE
Evans
Soe
S
Mon
Robinder
R
Singh
Lev R
LR
Ryzhkov
Veronika A
VA
Szalai
D000838:Anions / Q000737:chemistry; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry*; D008823:Micelles; D009942:Organometallic Compounds / Q000737:chemistry* / Q000528:radiation effects; D010084:Oxidation-Reduction; D010777:Photochemistry; D011725:Pyridines / Q000737:chemistry* / Q000528:radiation effects; D012428:Ruthenium / Q000737:chemistry* / Q000528:radiation effects; D012680:Sensitivity and Specificity
D000838:Anions; D008823:Micelles; D009942:Organometallic Compounds; D011725:Pyridines; D006147:Guanine; D012428:Ruthenium; D004247:DNA