rule of thumb for SDS-PAGE separation of small proteins?

Pete pkursula at
Wed Oct 28 09:02:37 EST 1998

Sometimes this helps: Prepare the samples as usual, i.e. add Laemmli
or whatever you use, but leave out the SDS from the gel while preparing
it. Include SDS in the running buffer however. I have seen some appr.
10-kDa proteins that differ by 2 amino acids separate quite well under
these conditions. The gel % around 15-20...

A 10 % gel has a lower resolution limit around 30 kDa, bad idea I

How about a native gel? That works for the same proteins mentioned above.
Just leave out all SDS and be sure that your native proteins move in the
correct direction :) (check the pI)

On Tue, 27 Oct 1998, Peter wrote:

> In article <3635C782.8F797225 at>, scorbitt
> <scorbitt at> wrote:
> > If you would like to increase your separation, I would reduce the percentage
> > of acrylamide/bis in your gels.  Try a 10% or 12%.
> > 
> > Ing-Nang Wang wrote:
> > 
> > >
> > >         I have to separate two proteins with 105 and 107 amino acids.  We
> > > usually use a 16% Tricine SDS-PAGE.  But I sometimes don't get a
> > > consistent separation.  I wonder if there is a rule of thumb for a small
> > > protein separation?  Would a 20% gel be better?  Or maybe a 10% - 20%
> > > gradient gel?  Ideally, the two bands should be at least 1 mm apart
> > > after staining.

|)    |/
|etri |\ursula

Petri.Kursula at

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