His TAG protein purification

[Paul Jasper]

Per Mygind wrote:
> 
> Raimo J Pollanen wrote:
> 
> > I have started a project to purify a protein (recombinant ) His Tag from
> > E coli and after Nickel (Novagen) column I have still big proteins
> > (double band around 100-150kD) which follows even after  ion exchange
> > and gel filtration steps...? How could I get eid of that ? My own
> > protein is sized aroun 21-22kD??
> >
> >  Raimo
> 


I would put your "purified" protein solution including the contaminant
over a column (centricon or amicon) which has a 40-50kD molecular weight
cut-off... your small protein will run through the column and the
contaminating 100-150kd protein will be trapped above the column...
Don't forget that your product is in the flow-through this time!!! 

hope that helps... 

Paul



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