Free radicals in biological systems

Pou, S., Hassett, D.J., Britigan, B.E., Cohen, M.S., and Rosen, G.M. 1989. Problems associated with spin trapping oxygen-centered free radicals in biological systems. Analytical Biochemistry 177 1-6. 

Guanine is the most easily oxidizable natural nucleic acid base [8] and many oxidants can selectively oxidize guanine in DNA [95]. Here, we focus on the site-selective oxidation of guanine by the carbonate radical anion, COs , one of the important emerging free radicals in biological systems [96]. The mechanism of COs generation in vivo can involve one-electron oxidation of HCOs at the active site of copper-zinc superoxide dismutase [97, 98], and homolysis of the nitrosoperoxycarbonate anion (0N00C02 ) formed by the reaction of peroxynitrite with carbon dioxide [99-102]. 

Garrel, C. Fontecave, M. Nitric oxide chemistry and biology, Analysis of Free Radicals in Biological Systems Eds. Favier, A. E. Cadet, J. Kalyanaraman, B. Fontecave, M. Pierre, J.-L. Birkhauser Verlag Basel, 1995, pp. 21-35. 

Buettner GR (1988) In the absence of catalytic metals ascorbate does not autoxidize at pH 7 ascorbate as a test for catalytic metals. J Biochem Biophys Methods 16 27-40 Buettner GR, Jurkiewicz BA (1995) Ascorbate radical a valuable marker of oxidative stress. In Favier AE, Cadet J, Kalyanaraman B, Fontecave M, Piere JL (eds) Analysis of free radicals in biological systems. Birkhauser, Basel, pp 145-164... 

Parker VD (1998) Radical reactivity of radical ions in solution. Radical-radical and radical-substrate coupling mechanisms. Acta Chem Scand 52 154-159 Poskrebyshev GA, Neta P, H uie RE (2002) Temperature dependence of the acid dissociation constant of the hydroxyl radical. J PhysChem A 106 11488-11491 Pou S, Hassett DJ, Britigan BE, Cohen MS, Rosen GM (1989) Problems associated with spin trapping oxygen-centered free radicals in biological systems. Anal Biochem 177 1-6 Raghavan NV, Steenken S (1980) Electrophilic reaction of the OH radical with phenol. Determination of the distribution of isomeric dihydroxycyclohexadienyl radicals. J Am Chem Soc 102 3495-3499... 

Blois, M. S., Jr., et al. (eds.) (1961). Free Radicals in Biological Systems, Proceedings of a Symposium held at Stanford University, March 1960 , Academic Press, New York. 

Detection and identification of free radicals in biological systems... 

Because of their extreme reactivity, the existence of free radicals in biological systems was generally not considered possible until Gerschman and associates (G3) hypothesized that oxygen poisoning and X-irradiation have a common basis of action. Here, they reported the homolytic dissociation of water by ionizing radiation. 

The general acceptance of free radicals in biological systems did not occur until the discovery (Mila) of superoxide dismutase (SOD), of which there are two enzymes, cytoplasmic CuZn-SOD and mitochondrial Mn-SOD. These enzymes catalyze the following reaction ... 

L. H. Piette, I. Yamazaki and H. S. Mason, in Free Radicals in Biological Systems (Eds. 

Nakamura, T. In Free radicals in biological systems (M. S. Blois, Jr., ed.). New York Academic Press 1961. 

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