Protein Precipitation

Stephen R. Lasky Stephen_Lasky at
Mon Apr 25 08:05:29 EST 1994

In article <1994Apr23.211400.6633 at>,
u6069416 at wrote:

> In article <2oejvv$scv at> volcs at (Sam Volchenboum)
> writes:
> >I need to precipitate a protein sample coming off a FPLC column for
> >subsequent SDS-PAGE.  I was going to precipitate with 10% TCA and then wash
> >with 10% TCA, but I read that the TCA can change the pH so as to affect the
> >PAGE.  Then someone told me to wash with acetone.  Fine, but can't I just
> >precipitate with one volume of acetone from the start?  Anyways, do any of
> >you have ideas/protocols/refs which will precipitate small amounts of
> >protein and not affect the PAGE? (Or should I just use TCA and be done with
> >it...)

Protein precip with  3 VOLUMEs of ice cold acetone works quite well.  I
usually add come carrier protein, like soybean trypsin inhibitor, but if
your protein concentration is high enough you don't need too.  Just let the
solution sit overnight, spin it down and dry it (just like you would in
EtOH ppt of nucleic acids).  Ten you can resuspend it in whatever volume
you want of 1X loading buffer and run it on the gel.  (I used this tech
becuase TCA ppt caused too much of a pH change.)
Stephen R. Lasky, Ph.D.       Brown University/Roger Williams Medical
e-mail: Stephen_Lasky at         LandLine: 401-456-6572
A nuclear war could ruin your whole day.

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