Is there any inexpensive way to separate RNA from DNA?

Song Tan tan at
Thu Dec 1 04:09:26 EST 1994

In article <29NOV199411301289 at>, chee1tq at (Xu,
Liang) wrote:

> I am doing plasmid DNA separation from fermention, we are using RNAse to
> degrade the RNA and then get rid of RNA, but the RNAse is too expensive
> and is there any more ecnomical way to do this?

We use RNase to degrade RNA in large scale plasmid preps (100 - 300 mg
plasmid) and the cost of the RNase is really not a major cost of the prep
(I estimate that 1 g of RNase at US$100-200 is enough to prepare 50 g of
plasmid DNA!). As I mention in a followup to the posting "How to separate
plasmid DNA from chromosome DNA", you can also use a Sephacryl S1000
column to fractionate plasmid DNA from small RNA fragments.  References
can be found in that posting.

Song Tan
Institute for Molecular Biology and Biophysics
ETH-Honggerberg (Swiss Federal Institute of Technology)
8093 Zurich, Switzerland
email:  tan at

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