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Updated: Dec 11, 2025

Streamlined Purification of Plasmid DNA From Prokaryotic Cultures
Published on: January 5, 2011
Primary Purification of Plasmid DNA Using Differential Isopropanol Precipitation
Alexandra Wagner1, A Rita Silva-Santos1, Sara Sousa Rosa1
1Department of Bioengineering, Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.
Abstract:
A method for the intermediate recovery of plasmid DNA (pDNA) from alkaline lysates is described that comprises differential isopropanol precipitation steps. In a first low-cut precipitation, a smaller amount of isopropanol (20% v/v) is used so that only high molecular weight RNA precipitates. After solid liquid separation, a high-cut precipitation is performed by bringing isopropanol concentration to 70% v/v to precipitate pDNA. Tests made with lysates show that the differential precipitation increases purity threefold compared to the conventional one-step precipitation at 70% v/v without affecting pDNA recovery (>80%).
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