A new rapid procedure for the preparation of plasmid DNA

This report describes a simple and efficient procedure for the isolation of plasmid DNA free from chromosomal DNA, cellular RNA, and protein. The technique comprises a modified cleared lysate procedure of D.B. Clewell and D.R. Helinski (1969, Proc. Natl. Acad. Sci. USA, 62, 1159-1166) followed by high-performance liquid chromatography on a Dupont Bioseries GF250 surface stable diol-coated silica gel permeation column (Zorbax) for the final purification of the plasmid DNA. The use of HPLC facilitates rapid and high-resolution separations within 3-4 h. Plasmid DNA produced in this manner retains its biological activity and exhibits yields equal to those obtained by the conventional cesium chloride-ethidium bromide density centrifugation method.