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

Pete pkursula at cc.oulu.fi
Wed Oct 28 09:02:37 EST 1998

```Sometimes this helps: Prepare the samples as usual, i.e. add Laemmli
buffer
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
think.

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 mindspring.com>, scorbitt
> <scorbitt at mindspring.com> 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 oulu.fi

http://cc.oulu.fi/~pkursula

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