protein purification

Randall Willis willis at
Wed Apr 3 09:12:43 EST 1996

You don't tell us a lot about the protein or it's degradation products.

If they're small enough, gel filtration may be useful in separating the 
full sized protein from the fragments but you will require a resin which 
has a low molecular weight window of resolution.

It may be possible that there are differences in the interaction of the 
proteolytic products with ion exchange resins (ie some of the charged 
residues may have been clipped off)

Again, depending upon how much is lost in degradation, if your protein 
has an affinity for some substrate, it may be that only the full sized 
protein will bind to its ligand.  This will allow you to use affinity 
chromatography to isolate the full protein.

There may be differences in the solubility of the fragments in high salt 
(ie ammonium sulfate) and you may be able to perform a salting out 
experiment.  If they are all equally soluble at the same levels of salt, 
it may be possible to use this solution on a hydrophobic column and see 
if there are differences in behaviour on this resin.

If there are differences in pI, it may be possible to perform 

Good luck and let us know how it goes.

Randall C Willis, Aliquotes Press
"ALIQUOTES: A Journal of Molecular and Biochemical Humour"
58 Balfour Ave.
Toronto, ON M4C 1T6  CANADA

rogerb at   willis at

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