Hi, I would like to ask if E. coli SoluBL21 cells are really so good to produce soluble proteins? I have read that they should contain extra chaperons. Will there be no problem with their removal? We had a problem with the Cpn60 after expression of our target protein in Arctic Express. We couldn't remove it. Thanks for the answers ...
It depends on how your protein is kept soluble. If it's still in the barrel of the GroEL chaperone you won't separate your protein from the chaperone. The folding mechanism requires energy (ATP) and I remember publications where they used ATP (I think they also added Mg) during purification to release the protein from chaperones but it could also be that they had DnaK as the chaperone in that case (sorry for my bad memory).
So, if ATP doesn't help your protein is difficult to fold and stays soluble only in the protected chaperone complex.
I assume you are purifying His-tagged protein by using Ni2+ or Co2+ based resin, then it may be helpful to wash the column with your wash buffer containing additional 2.5 mM ATP, 5 mM MgCl2, and 0.5% Triton X-100 or NP-40. By doing this, you may remove the co-bound Cpn60 or DnaK protein.
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