title: Superhelix densities of circular DNA's: a generalized equation for their determination by the bouyant method.
abstract: Equations for the measurement of the supertwisting of circular DNA's from banding positions in buoyant density gradients containing intercalating dyes have required the use of SV40 DNA isolated from virions as a reference DNA. These equations are modified to allow the use of any closed circular DNA of known superhelix density as a reference DNA.
mesh_terms: D002499:Centrifugation, Density Gradient / Q000379:methods; D004270:DNA, Circular; D004279:DNA, Viral; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D013539:Simian virus 40 / Q000648:ultrastructure
chemical_list: D004270:DNA, Circular; D004279:DNA, Viral