Proteins which run high on SDS-PAGE

[Nick Fisher]

In article <3187B8DF.7650 at ibex.ca>, Achim Recktenwald <achim at ibex.ca> wrote:

> Matt Parker wrote:
> > 
> >         Hi! We are studying a protein of 33 kDa, which consistently runs
> > as about 39 kDa on SDS-PAGE (after boiling 3 mins in SDS buffer). We also
> > are studying a fragment of this protein, of about 19 kDa, which runs at
> > about 25 kDa. Does anybody have any clues as to why this is going on?
> 
> 
> Could it be glycosylated ?   On average protiens bind about 1.4g of SDS
per gram 
> protein. Glycosylated ones bind less, that means they are less charged,
they are 
> running as higher molecular weights.
> 
> Achim

glycoproteins tend to give very fuzzy,indistinct, microheterogeneous bands.
The glycans tend to inhibit Coomassie and silver binding too.
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