precipitating proteins w/ ethanol

Ian Mc i.mcfarlane at
Mon Mar 8 09:40:45 EST 1999

Hi Peter,

Have you got a protocol or a ref.for this technique?

I need to recover proteins from an SDS solution and although EtOH and
acetone will bring them out of solution my usual method of resolubilising
in 1M Tris pH10.4 isn't working well.

One other thought, do you know if urea precipitation will work in the
presence of SDS?


Ian McFarlane

In article <pxpst2-0803990856500001 at>,
pxpst2 at (Peter) wrote:

> In article <36DF1563.BF89D47D at>, Katherine Walstrom
> <kwalstro at> wrote:
> > I have some dilute protein samples that I need to concentrate and run on
> > an SDS-PAGE gel.  I can't find a detailed protocol for precipitating
> > proteins, although what I've read suggests that ethanol works well.  I
> > want to precipitate all the proteins, not just selectively precipitate
> > some of them.
> The best method for recovery of dilute proteins is to use phenol ether
> extraction.  I can without much problem, recover 10 ng from 1ml of aqueous
> solution and it is not selective.  It works great on all proteins.  TCA,
> acetone and ETOH are selctive and only work with relative high amounts of
> protein.  Another problem with precipitation is that sometimes you you are
> not able to resolvate your protein following the preciptaion.  TCA is
> notorious for this because it is a potent dehydrator(sp?)
> -- 
> Peter
> " Don't you eat that yellow snow
>      Watch out where the huskies go"
>                                     FZ

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