staining a chargeless protein

[Wayne R. Baker]

In bionet.molbio.proteins,  Olin Anderson  <oandersn at pw.usda.gov> 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.  

  Not to be nosey, but a 55 kDa protein that has only 6 different amino
acids? Is this naturally occuring? 

:Any suggestions how to stain/detect this polypeptide in a gel?

  Coomassie interacts with basic groups, which won't do you much good.
Any chance you could use a gel reader in the 200 nm range? Your
background would probably be pretty high but it might work. You might
also browse through another discussion in this group on the effect of
proline content on mobility.

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