Store DNA concentrated or dilute?

Stephen R. Lasky Stephen_Lasky at
Tue Mar 12 08:20:12 EST 1996

In article <Do4L55.HtG at>, pnh at (Paul N
Hengen) wrote:

> Bernard Murray (bernard at wrote:
> : A long time transfecter in our lab maintains that storing plasmids
> : at too high a concentration (eg. much more than 1 g/l) leads to
> : concatamer formation which reduces transfection efficiency.
> How do concatamers form in purified cccDNA???? I can see how a batch of
> restriction digested vector DNA which is frozen and thawed can give you
> transformants with concatamers, but with cccDNA it doesn't make sense.

Exactly, and in addition, 1 migrogram per microliter is not really a
concentrated solution of DNA.  I have been storing plasmids frozen at 2 to
5 ug/ul for years and never had any problems with restriction digests,
isolating inserts, or transfecting the plasmids into bugs or eukaryotic
cells.  I haven't tried to sequence DNA that has been stored for a long
time like this, but I suspect that it would sequence.


Stephen R. Lasky Ph.D.   Brown U/Roger Williams Medical Center,  Providence, RI.   
Phone: 401-456-5672     Fax: 401-456-6569     e:mail: Stephen_Lasky at
America may be unique in being a country which has leapt from barbarism to decadence without touching civilization.  John O'Hara.

More information about the Methods mailing list