Analysis of gamma radiation-induced damage to plasmid DNA using dynamic size-sieving capillary electrophoresis

Bacterial plasmids and the chromosomal DNA of many organisms adopt naturall y the negatively supercoiled conformation. Therefore, the irradiation of su ch plasmids could be used to model conformational changes of chromosomal DN A associated with externally-induced damage. We have applied dynamic size-s ieving capillary electrophoresis (CE) to monitor the damage of three DNA pl asmids, over an unprecedented base pair (bp) size range (2870-27 500 bp), u pon exposure to gamma-radiation (20-400 Gy), Predominantly, CE with UV abso rbance detection in the absence of DNA intercalating dyes was employed to p reclude undesirable, induced plasmid conformational changes. Plasmid sample s and their enzymatic digestion products were analyzed using both CE and sl ab gel electrophoresis (SGE) in order to verify the conformation of sample components. Relative to SGE, CE analyses revealed more fine structural feat ures of plasmid degradation. (C) 2000 Elsevier Science B.V. All rights rese rved.