PEG staining in protein gels?

Wendy Bedale bedale at
Thu Feb 24 11:46:41 EST 1994

	I recently purified a protein where one of the 
last steps was dialysis vs. solid PEG to concentrate 
the protein.  I dialyzed again vs. the final protein 
storage buffer, and ran the protein on an SDS gel.  
After Coommassie staining, I noticed that there is a 
broad smear that is migrating at around 8000 
(I used PEG 8000 in the first dialysis, incidently). 
This smear does not look like protein- 
it is stained kind of a brownish color which looks a ghostly 
white against a dark background.  The protein sample prior to 
the PEG dialysis does not exhibit this strange smear.  
I am wondering if anyone else has observed anything like this,
and if anyone can tell me if this strange smear is PEG or not.  
 							Wendy Bedale
							bedale at

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