Quantitative analysis of plasmid forms by agarose and capillary gel electrophoresis

Plasmids may appear in different forms: circular with different degrees of coiling, partially cleaved or linear, and multimeric as concatamers or cate nates, Capillary gel electrophoresis (CGE) of plasmid samples allows the de termination of plasmid form distribution. Monomeric and dimeric plasmid DNA forms were separated by both CGE and agarose gel electrophoresis (AGE), Th e pattern of isoform bands from AGE was compared to the corresponding peak pattern from CGE, and differences in the relative mobility of the plasmid f orms between the two methods were found, The comparison of AGE and CGE allo ws the assignment of AGE bands to CGE peaks. Additionally, the different is oforms can now be quantified by CGE. Routine plasmid form analysis by CGE m ay be automated, allowing easy, fast, and highly reliable quantification. C GE also offers high resolution and the amount of DNA required is very low, Therefore this method is very useful for the analysis of therapeutics based on plasmid DNA during their production, isolation, and formulation (C) 199 9 Academic Press.