Relative Rates and Potentials of Competing Redox Processes during DNA Cleavage: Oxidation Mechanisms and Sequence-Specific Catalysis of the Self-Inactivation of Oxometal Oxidants by DNA

Effects of Secondary Structure on DNA and RNA Cleavage by Diplatinum(II)

“…Although the results are consistent with an electron transfer mechanism, we have not detected 8-oxo-7,8-dihydroguanine, which is an excellent indicator of outer-sphere electron transfer (39)(40)(41)(42)(43)(44), and certainly there are inner-sphere guanine oxidation mechanisms that could produce piperidine-labile scission (4,14,38). It is difficult to imagine an inner-sphere oxidation reaction of Pt 2 (pop) 4 4-, since the complex does not have an activated oxygen atom and is not known to undergo any inner-sphere oxidation reactions (7).…”

“…For duplex DNA where only the 4′-and 5′-hydrogens are abstracted, the majority of cleavage by Pt 2 (pop) 4 4-is apparent prior to piperidine treatment, although there is a modest piperidine enhancement as expected for the 4′-hydrogen pathway (18). To elucidate the effects of hybridization on the available pathways and cleavage efficiency, we studied the cleavage of a single strand d[5′-A 1 T 2 G 3 C 4 C 5 C 6 T 7 T 8 G 9 C 10 G 11 T 12 A 13 T 14 ], which is a random coil in solution (14). The results of cleavage of this oligonucleotide both as a single-strand and hybridized to its complement are shown in Figure 1.…”

“…Portions used for end labeling were additionally purified on a 20% polyacrylamide gel, visualized by UV shadowing, and extracted from the gel, as described elsewhere (3). The 5′-32 P-labeled oligomer was prepared using T4 polynucleotide kinase (New England Biolabs) and 2′-deoxyadenosine 5′-[γ-32 P]triphosphate (Amersham) as previously described (14). Hairpin sequences were heated to 80°C and then chilled quickly to room temperature in a water bath to avoid formation of bulge complexes.…”

New Family of Ruthenium‐Dye‐ Sensitized Nanocrystalline TiO2 Solar Cells with a High Solar‐Energy‐Conversion Efficiency

“…The bonding of thiocyanate ligand is reminiscent of that observed in [Ru(HP-terpy)(Me2-bpy)(NCS)], [17] for which the bent R-N-C angle and linear N-C-S arrangement are an indication of the efficient transfer of the Ru II d p electron density to the p-accepting thiocyanate ligand. [18] Finally, this gross coordination geometry around the Ru II metal atom is akin to that of the ionic complexes [Ru(tpy)(bpy)(H 2 O)] 2+ and [Os(tpy)(bpy)(H 2 O)] 2+ (tpy: 2,2′;6′,2″-terpyridine), [19] which showed the simultaneous coordination of tridentate and bidentate chelates as well as a monodentate ligand. Figure 3 reveals the absorption spectra of 6, 7, and 8 in DMF.…”

Direct photo-induced DNA strand scission by a ruthenium bipyridyl complex

“…Light-induced cleavage of DNA by a variety of metal complexes, predominantly ruthenium complexes [1][2][3][4][5][6][7][8], and to a lesser extent, metalloporphyrins [9,10], metal salen complexes [11,12], and others [13][14][15][16][17][18] have been extensively studied due to their potential application as therapeutic agents [19][20][21]. The redox-active metal complexes were found to mediate nucleobase damage typically in the presence of oxidizing agents, such as hydrogen peroxide or per acids.…”