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. 1973 Oct;70(10):2884–2887. doi: 10.1073/pnas.70.10.2884

Isolation of Circular DNA Molecules from Whole Cellular DNA by Use of ATP-Dependent Deoxyribonuclease

Tsunehiro Mukai 1, Kenichi Matsubara 1, Yasuyuki Takagi 1
PMCID: PMC427131  PMID: 4355370

Abstract

A technique is described for isolation of plasmid DNA in closed and open circular double-stranded forms from bacterial cells, by use of ATP-dependent deoxyribonuclease purified from Micrococcus luteus. This DNase, acting only upon linear DNA molecules, degrades all bacterial chromosomal DNA extracted in the linear form. Circular plasmid DNAs are left intact, and are then separated by sedimentation through a sucrose gradient. Unlike previous techniques for analysis of plasmid DNA, this technique can be used to isolate not only closed circular DNA but also open circular DNA. Several plasmids, such as those from phage (λdv1 and λdv21), a colicinogenic factor (Col E2), a sex factor (F8′ gal), and “minicircles” in Escherichia coli 15, in both the open and closed circular forms, were well separated from chromosomal DNA by this technique.

Keywords: plasmid, open and closed circular DNA, sedimentation

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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