staining a chargeless protein

Hisham Ibrahim hishamri at
Wed May 15 03:00:55 EST 1996

In article <4nb7ud$s4v at>, Olin Anderson
<oandersn at> wrote:

> We are working with a 55 kDa polypeptide that has no charged amino acids.
> Attempts to stain the polypeptide on PAGE gels has failed - tries
> included commasie blue, amido black, silver, copper stain, Sypro, 
> anilionaphthalene sulfonate, and fluorescein isothiocyanate.  The only
> amino group is the N-terminal and it seems unreactive/blocked.  The
> only amino acids in the polypeptide are P, G, Q, Y, T, and S.  Any
> suggestions how to stain/detect this polypeptide in a gel?

I am wondering that the polypeptide may not entered the PAGE gel at all,
because there is no enough net charge on the peptide to support migrate
toward cathode. So, you have better try first SDS-PAGE to look whether the
problem exists in the staining or the migration.

If the problem is staining deficiency, you may run the peptide on TLC and
visualize the band by UV illuminator. Protein can be visualized by UV on
TLC sheets.

Best luck.


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