Mobility Shift and Glutamic Acid

Ken Doyle kdoyle at
Tue Mar 7 15:27:09 EST 1995

stefan at (Stefan Einar Stefansson) wrote:
> Hi
> I am currently doing mobility shift on purified transcriptional
> factor. By substituting the potassium chloride for potassium
> glutamic acid, I can get much stronger shift. Unfortunately,
> the free probe, barely separates from the one being shifted,
> when run on the gel.
> Has anyone encountered this problem, and/or knows how to get
> a better separation, of the free probe from the shifted complex?
> Hope to hear from as many as possible,
> Stefan
> stefan at

The separation is dependent on a lot of factors: could you provide
more information such as -

the size of the probe and factor
the % gel being used
gel running buffer
voltage gradient used

If you are shifting a relatively small factor (<10 kD) with a small 
probe (<20 bp) then you will need to optimize all these factors to 
obtain the best separation.

kdoyle at

***Opinions are my own, and not my employer's, etc.***

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