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Comparison of nucleoid and alkaline sucrose gradients in the analysis of inhibitors of DNA repair in human fibroblasts

Journal Article · · Biochem. Biophys. Res. Commun.; (United States)
In ultraviolet-irradiated human fibroblasts inhibitors of DNA polymerases alpha (cytosine arabinoside, aphidicolin) and beta (dideoxythymidine) blocked polymerization of repair patches and accumulated large numbers of single-strand breaks in alkaline sucrose (up to 4-5 in 10/sup 8/ daltons). In nucleoid gradents, however, the restoration of DNA supercoiling to control levels after relaxation during excision repair was prevented only by aphidicolin, not be cytosine arabinoside or dideoxythymidine. These chain-terminating inhibitors must therefore generate breaks in DNA that are masked by proteins (possibly repair enzymes) that cannot be removed by the high-salt treatment of nucleoid gradients. Alkaline sucrose and nucleoid gradients therefore reveal different facets of the DNA breakage and rejoining during repair. The inhibitor of poly(ADP-ribose) synthesis, 3-aminobenzamide, had no effect on nucleoid sedimentation, implying that synthesis of this polymer plays no significant role in completion of repair of ultraviolet damage in human fibroblasts.
Research Organization:
Univ. of California, San Francisco
OSTI ID:
6123904
Journal Information:
Biochem. Biophys. Res. Commun.; (United States), Journal Name: Biochem. Biophys. Res. Commun.; (United States) Vol. 107:1; ISSN BBRCA
Country of Publication:
United States
Language:
English