title: Ethidium analogues with improved resolution in the dye-buoyant density procedure.
abstract: Analogues of ethidium chloride with large quaternary side chains have been synthesized and evaluated for improved resolution in the dye-buoyant density system for the separation of open and closed circular DNA. These compounds are similar to propidium which differs from ethidium by the replacement of an ethyl group by a methyldiethylaminopropyl group. The new analogues contain a triethylamino group attached to a methylene chain with 3, 5 or 7 carbons. With PM2 DNA the observed separation for propidium is 1.97 times that of ethidium and the new dyes show separations relative to ethidium of 2.27, 2.66 and 2.77. A correlation is established between the mass of the dye component and the observed separation which is retionalized on the basis of the four component thermodynamics describing this system.
mesh_terms: D001435:Bacteriophages; D002499:Centrifugation, Density Gradient / Q000379:methods; D004270:DNA, Circular / Q000302:isolation & purification*; D004279:DNA, Viral / Q000302:isolation & purification*; D004996:Ethidium / Q000031:analogs & derivatives*; D008433:Mathematics; D008970:Molecular Weight; D011549:Pseudomonas; D013329:Structure-Activity Relationship
chemical_list: D004270:DNA, Circular; D004279:DNA, Viral; D004996:Ethidium