DNA bases oxidation

Adam W, Arnold MA, Nau WM, Pischel U, Saha-Moller CR (2001b) Structure-dependent reactivity of oxyfunctionalized acetophenones in the photooxidation of DNA base oxidation and strand breaks through photolytical radical formation (spin trapping, EPR spectroscopy, transient kinetics) versus photosensitization (electron transfer, hydrogen-atom-abstraction). Nucleic Acids... 

Following the increase in the height of the DNA bases oxidation peaks and/or searching for new electrochemical signals such as of 8-oxoguanine, Fig. 29.1, the interaction of DNA with different compounds is evaluated. 

The ROS that are generated by these agents are in close proximity to DNA, giving rise to mutation via strand cleavage or DNA base oxidation. 

Singh NP, McCoy MT, Tice RR, Schneider EL (1988) A simple technique for quantation of low levels of DNA damage in individual ceUs. Exp Cell Res 175 184-91 CoUins AR, Dusinska M, Horvathova E,Munro E,Savio M,StetinaR (2001) Inter-individual differences in repair of DNA base oxidation, measured in vitro with the comet assay. Mutagenesis 16 297-301... 

DNA base oxidations have been also observed with copper complexes as, for example, CUCI2 in the presence of H2O2 (without (57-59), or with (60), DOPA) or O2 and reductant (T and G oxidations were observed), Cu-peptides in the presence of H2O2 or O2 (8-oxoguanine was characterized) (61), Cu-famotidine with 30 102 (T > G > C A oxidations were estimated) (62) or copper complexes of benzosulfonamides in the presence of H2O2, reductant and air (40). 

Because the carotenoids favour hydrophobic domains they are generally localised in the membranes and lipoproteins of animal cells. In this location they can influence the oxidation of membrane lipids and prevent the passage of free radicals from one cellular compartment to another. Thus, DNA in the nucleus is protected from intracellularly generated ROS by (at least) the nuclear membrane and from extracellular ROS by a number of membranes. Should ROS reach the nucleus, base oxidation can occur. The base most susceptible to oxidation is guanine, although all other bases can also be affected. The cell has the ability to detect damaged bases, excise them. 

Kasprzak, K.S., Diwan, B.A., Rice, J.M., Misra, M., Riggs, C.W., Olinski, R and Dizdaroglu, M. (1992). Nickel(II)-mediated oxidative DNA base damage in renal and hepatic chromatin of pregnant rats and their fetuses. Possible relevance to carcinogenesis. Chem. Res. Tox. 5, 810-815. 

Measurement, chemistry, and biological importance of oxidative DNA base damage ... 

A different strategy has been applied in our work, that emphasizes the importance of DNA stability on hole transfer within double-stranded DNA. This work is based on determination of the overall yield of oxidized nucleosides that arise from the conversion of initially generated purine and pyrimidine radical cations within DNA exposed to two-photon UVC laser pulses. On the one hand, this work benefits from the excellent current knowledge of chemical reactions involving the radical cations of DNA bases, and on the other hand, from major analytical improvements that include recent availability of the powerful technique of high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (CLHP-ESI-MS/MS) [16-18]. 

One-Electron Oxidation Reactions of the Pyrimidine and Purine DNA Bases... 

One-Electron Oxidation Reactions of Cytosine and 5-methylcytosine DNA Base... 

A series of experiments investigated the effect of laser pulse intensity on the distribution of damage. For each pulse intensity, DNA samples were exposed to three different doses. The quantum yield for the formation of lesions, expressed with respect to total DNA bases, was then calculated by linear regression analyses. At all intensities, the formation of lesions was found to be linear with respect to the applied dose. Oxidized nucleosides, including... 

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