Protein purification problem

Dr. Hiranya S. Roychowdhury hroychow at nmsu.edu
Fri Mar 12 22:36:50 EST 2004

How do you know that what you are seeing with stains-all IS the protein of 
your interest?  I find it curious that a polypeptide will not stain with CBB-R 
or silver!  Stains-all stains phosphate and glycosidic residues and, to a 
lesser extent non polar conjugates (albeit showing different colors). So, if 
what is being stained does not migrate in an electric field, I doubt that it 
is a polypeptide. 

Quoting gilbertjack at hotmail.com:

> I am currently working on the most difficult project I have ever seen and
> have finally been forced to take the plunge and ask for outside assistance.
> This protein is a novel type from bacteria. Size exclusion chromatography
> suggests it to be 35-45kDa. It does not stain by coomassie, silver stain or
> any traditional techniques on SDS-PAGE. However, it is stained by Stains-All,
> but this shows it to be stuck at the stacking/resolving gel interface. 
> We have tested for amino-sugars and found none. 
> Does anyone have any idea why a protein would not travel through a
> polyacrylamide gel at all?
> If anyone has noticed anything like this before I would love to speak with
> you in more detail. 
> Yours sincerely,
> Jack Gilbert
> http://biowww.net/mynews/tree.php?group_name=bionet_molbio_proteins&begin=0

Hiranya S. Roychowdhury, Ph.D.
Coll. Asst. Professor,
Molecular Biology,
Dept. of Chemistry & Biochemistry
Rm# 336, Chemistry Bldg.; MSC 3MLS
New Mexico State University
Las Cruces, NM 88003

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