Most commonly plasmids are manufactured by fermentation of E. coli. In the cells several isoforms of the plasmid are generated: supercoiled (sc), open circular (oc) and linear as well as dimeric forms. After alkaline lysis plasmids are accompanied in solution by genomic DNA (gDNA), RNA, proteins and other cell compounds . In addition to these impurities, the plasmid isoforms have to be separated efficiently in order to get a final product containing > 95 % of ccc form . Chromatographic resins used in biotechnology are usually designed for the separation of polypeptides, providing only low capacity for polynucleotides (< 1 mg/mL).
In this work we present an optimised purification step for large scale purification of therapeutic applicable pDNA, based on an alternative chromatography resin (CIM Convective Interaction Media®).