ACTION OF HYDROGEN PEROXIDE ON HUMAN FIBROBLAST IN CULTURE |
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Authors: | M Edwiges Hoffmann Rogerio Meneghini |
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Institution: | Department of Biochemistry, Institute of Chemistry, University of Sao Paulo. CP 20780, SEo Paulo, Brazil |
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Abstract: | Abstract— Human fibroblasts in culture lose the capacity of proliferating when exposed to hydrogen peroxide in the concentration range of 1 to 10 μ M . The toxicity of H2O2 to xeroderma pigmentosum cells (XP12RO). defective in excision repair of lesions produced by UV-irradiation, was about twice as high as to cells proficient in excision repair (VA13). This compound produces single-strand breaks in intracellular DNA but not in purified DNA. These breaks are in situ physical discontinuities rather than alkali-labile bonds, and their generation occurs at the same extent at 4°C and 37° indicating that they are not produced by an endonuclease. The results favor the hypothesis that H2O2 reacts in the cell producing a radical species which brings about the formation of DNA single-strand breaks. These breaks are effectively repaired by both XP12RO and VA13 fibroblasts. The possible reason for the lethality of H2O2 is discussed. |
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