Rapid analysis of plasmid topoisomers by anion exchange chromatography

During large-scale plasmid fermentation, plasmids are maintained predominantly in a supercoiled, covalently closed circular form. During the downstream process some of the plasmids might become nicked and they will be transformed in open-circular and linear forms. For a fast and reliable characterization of pDNA samples Schuchnigg et al. developed an HPLC method with a high resolving power based on the TSKgel® DNA-NPR anion exchange HPLC. In this app note from Tosoh Bioscience, explore how the TSKgel DNA-NPR is packed with 2.5 µm hydrophilic non-porous polymer beads modified with a weak anion exchange group which offers fast mass transfer, a key to achieve high resolution. The small particle size and the fast mass transfer of non-porous beads can be exploited to speed up the analysis. By using pBR322, one of the first widely used E. coli cloning vectors, it is demonstrated that the method can be transferred from HPLC to UHPLC systems.