Gel Shift Probe

gc genecutl at
Mon Apr 4 16:11:50 EST 1994

In article <smrodems-010494000151 at>,
smrodems at (Steve Rodems) wrote:

> Iv'e been seeing some strange things with 32P labeled probes in my gel
> shift experiments.  In a control lane with no extract added my probe is
> consistently two bands about 1 cm apart at the bottom of a 5-10%
> polyacrylamide gel (all other lanes have the same thing).  Sometimes I get
> a couple other bands above and below the major ones.  I fill in 5'
> overhangs (4 nt) to label, my label is the first nucleotide added in the
> fill in, and it labels only once on each end.  The DNA I use has been
> either gel purified 30 bp or two 30 nt oligos annealed.  I thought that
> maybe it could be incomplete fill in so that I have a range of labeled
> probes different by 1-4 bps but I wasn't sure if the separation would be
> that great.  Does anyone have any ideas or has anyone seen this before?

Maybe you're seeing single stranded DNA.  Try boiling a bit of probe and
running it along side unboiled probe.


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