"mystery bands" in SDS-PAGE

Dima Klenchin klenchin at macc.wisc.edu
Thu Mar 28 18:17:35 EST 1996

In article <315AF4DF.73AA at acs.ucalgary.ca>,
   "Fiona M. Mattatall" <fmcowman at acs.ucalgary.ca> wrote:
->My laboratory is having some problems with bands appearing on our 
->SDS-PAGE gels.  The bands always run in the 80 to 100 kDa range.  They 
->appear in all lanes of the gel, including those that do not have 
->protein samples applied to them.  We have concluded that this 
->contamination must be coming from either the sample buffer, running 
->buffer, or the apparatus itself.  We are having some difficulty 
->figuring out what is causing the problem.  If anyone has seen this in 
->their hands or has a solution please let me know.

This thing surfaces up in this group periodically. The only consensus
found is that these are nasty bands difficult to get rid of. As far as
their nature goes, 3 hypothesis exist:
	1. contaminant in beta mercaptoethanol
	2. contaminant in SDS
	3. Protein(s) from our own skin/hair (keratin?) finding thier way into
	   our samples. 
Many suggest that filtering of SDS sample buffer helps. I doubt it, for if
this is protein, it'll be dissolved by high SDS. I don't also think it's
(1) since the same is frequently seeing with DTT.

Anyway, they are usually very faint and have rather distinct appearance and
unlikely to result in any serious problems besides aesthetic ones. 

- Dima


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