title: Modification of PM2 DNA with N-acetoxy-2-acetylaminofluorene: changes in buoyant density, electrophoretic mobility and electron microscopic structure.
abstract: PM2 DNA, forms I and II, were chemically modified with the ultimate carcinogen N-acetoxy-2-acetylaminofluorene. The products were subjected to 3 analytical procedures: (i) buoyant density centrifugation in the presence of the intercalating dyes ethidium bromide or propidium diiodide; (ii) agarose gel electrophoresis: and (iii) electron microscopy. It was found that carcinogen-modified DNAs banded at higher densities in the presence of either dye. This effect was far more pronounced with form I DNA than with form II. Form I DNA showed a concentration-dependent decrease of migration velocity in agarose gel electrophoresis after modification; form II DNA exhibited a similar but smaller effect. Electron microscopy of form I DNA did not reveal a consistent correlation between the extent of chemical modification and the loss of superhelical turns. Form II DNA exhibited characteristic alterations such as aggregation of several PM2 molecules into network-like structures, kinky configuration, and probably single-stranded bubbles extending over 600-1500 bases.
mesh_terms: D015073:2-Acetylaminofluorene / Q000031:analogs & derivatives*; D000099:Acetoxyacetylaminofluorene / Q000494:pharmacology*; D001435:Bacteriophages; D002498:Centrifugation; D004278:DNA, Superhelical / Q000032:analysis; D004279:DNA, Viral / Q000032:analysis*; D004587:Electrophoresis, Agar Gel; D008854:Microscopy, Electron; D011549:Pseudomonas
chemical_list: D004278:DNA, Superhelical; D004279:DNA, Viral; D000099:Acetoxyacetylaminofluorene; D015073:2-Acetylaminofluorene