Staining problems

Peter Cherepanov peter.cherepanov at uz.kuleuven.ac.be
Mon Nov 26 06:53:05 EST 2001


Coomassie stains positivly charged amino acids and aromatics. There are a
couple of papers about it.
It happens sometimes (seldom) that protein isn't staind well with coomassie
and stained much better then other proteins with silver (the only example I
know about is HBsAg).
Any gel stained with coomassie you can stain with silver, just follow the
protocol from
Analytical Chem, 68, 5, 850-858, 1996. (It takes you only 1 to 1.5 hours).

for the cleavage - may be moderate concentrations of urea might help, I
never tried this protease though.
Cleavage in solution might be more efficient then right on the column.
Take care, your protein might precipitate after removal of MBP. As MBP is
known to solubilise fusion proteins.
May be add a mild detergent, like NP40 or CHAPS to keep it more soluble.

BTW, silver staining after coomassie was discussed here before - check the
archive
(http://www.bio.net/hypermail/METHDS-REAGNTS/)

good luck,
Peter

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