isopropanol to precipitate DNA: how much?

Gary K. gtk10583 at
Tue Feb 6 08:18:57 EST 1996

In article <4eqgtl$aco at>, zywzyw at (Zhengyang
Wu) wrote:

> Hi all!
> Sorry if my question is too simple for you!
> Isopropanol can be used instead of ethanol for DNA precipitation, but how
> much shall one use? Some mAnual says 1 volume, while some others 0.8 vol.,
> 1.5 vol., 2 vol. and so on. Which one is right (or most efficient), or it 
> does not matter? I can not find any book which describes the use of
> closer.
> Isopropanol precipitation does not require freezing, lets more efficient
> removal of salts, right? Are there more advantages with it?
> Thanks for your reply! 

I use 0.6 x vol isopropanol for DNA precipitations in my plasmid prep
protocol.  I have heard that isopropanol does not precipitate some
proteins as efficiently as ethanol.  Therefore you would expect less
protein contamination in your DNA pellet.  However, higher concentrations
of isopropanol as well as prolonged incubation will bring down these
proteins in your spin.


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