Protein precip. from Guanidine

Nick Theodorakis nicholas_theodorakis at urmc.rochester.edu
Tue Oct 12 22:47:41 EST 1999


In article <3803d94b.356044020 at news>,
  jrt at home.com (John Thompson) wrote:
> Kresten <kresten at my-deja.com> wrote:
>
> >Could anybody please suggest a method for precipitation of protein
for
> >subsequent SDS-PAGE.
> >
> >My sample volume is 200 microliters and contains 40 micrograms of
(pure
> >protein). Furthermore the sample is 6.8M in Guanidine Hydrochloride.
> >
>
> Why precipitate at all. You can probably add 5X sample buffer and load
> the sample directly on SDS Page.  If you need to concentrate to I'd
> suggest a low mw cutoff spin filter (try Amicon or Millipore) that
> will allow you to change the buffer and reduce the volume at the same
> time.
>
> Yours,
> John Thompson
> Merck Research Labs
>

The problem will be the ionic content of the guanidine, which will
surely mess up the electrophoresis. It wouldn't be a problem with urea
(but I would skip the boiling step). Is there a way the the original
poster could dialyze against urea to remove the guanidine (assuming a
denaturant was needed to keep it in solution)?

Nick


--
 _______________________________________________
| Nick Theodorakis                              |
| nicholas_theodorakis at urmc.rochester.edu       |
| (previously theodorn at gusun.georgetown.edu)    |


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