title: Increased DNA topoisomerase I activity in aging human cell chromatin.
abstract: Chromatin-associated DNA topoisomerase I activity was measured in human diploid fibroblasts during in vitro aging. No difference was detected as a function of cell age in the nicking and the closing activities of the DNA-unwinding enzyme. The capacity of type-I topoisomerase to relax superhelical DNA molecules was, however, increased in aged cells. An age-related increase in nucleoprotein content was also observed.
mesh_terms: D000375:Aging; D002453:Cell Cycle; D002478:Cells, Cultured; D002843:Chromatin / Q000201:enzymology*; D004261:DNA Replication; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004278:DNA, Superhelical / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000166:cytology; D008970:Molecular Weight; D013379:Substrate Specificity
chemical_list: D002843:Chromatin; D004278:DNA, Superhelical; D004264:DNA Topoisomerases, Type I