title: Comparative investigation of rate of sedimentation of DNA from human fibroblasts and tumor cells of HeLa line before and after moderate heating.
abstract: Changes in DNA after heating of human cells at 43.5 and 44 degrees C were found for the first time by means of sedimentation in an alkaline sucrose gradient. These changes are probably mainly determined by three processes: the appearance in DNA of alkali-labile bonds, the formation of stable DNA--protein complexes, and changes in the superstructure of the DNA, in particular partial unfolding of the nucleosomes. The existence of a mechanism for nonexcision repair of thermal lesions in DNA by an enzyme ("repurinase") catalyzing the formation of a glycoside bond between the base of a purine precursor of DNA and the deoxyribose residue of an apurine component is suggested.
mesh_terms: D000328:Adult; D000367:Age Factors; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D055598:Chemical Phenomena; D002621:Chemistry; D004247:DNA / Q000378:metabolism*; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000378:metabolism; D004622:Embryo, Mammalian; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006367:HeLa Cells / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D008297:Male; D009690:Nucleic Acid Conformation
chemical_list: D004273:DNA, Neoplasm; D004247:DNA