PAGE questions: long run times and streaking

[Michael Witty]

On 28 Jan 2002, Deva wrote:

> I've been using 12% acrylamide gels to PAGE purify 50mer oligos.  I
> recently switched to 15%, and I'm getting better resolution, but my
> run times are much longer.  I have to wait 7-8 hours as opposed to 4-5
> for the oligos to migrate long enough for good separation.  Is this
> normal?

Sounds normal to me.  Why not run the gel overnight (if you apparatus does
not leak!).

> Also, I have some streaking above my 50mers that I was able to cut
> down on by reducing the voltage.  I read one protocol that suggested
> overlaying the sample with methanol, because high molecular weight
> nucleic acids tend to get trapped at the surface of the gel well.  Has
> anyone tried this methanol overlay technique?

Havn't heard of this.  Can you give us a citation?  Regards, Mike.