Protein Precipitation

u6069416 at ucsvc.ucs.unimelb.edu.au u6069416 at ucsvc.ucs.unimelb.edu.au
Sat Apr 23 06:13:59 EST 1994


In article <2oejvv$scv at fermat.mayo.edu> volcs at fermat.mayo.edu (Sam Volchenboum)
writes:
>I need to precipitate a protein sample coming off a FPLC column for
>subsequent SDS-PAGE.  I was going to precipitate with 10% TCA and then wash
>with 10% TCA, but I read that the TCA can change the pH so as to affect the
>PAGE.  Then someone told me to wash with acetone.  Fine, but can't I just
>precipitate with one volume of acetone from the start?  Anyways, do any of
>you have ideas/protocols/refs which will precipitate small amounts of
>protein and not affect the PAGE? (Or should I just use TCA and be done with
>it...)

If the protein sample is in low salt or organic solution (e.g. from reverse
phase chromatogrphy) then I'll just reduce the volume by speed-vac.
If the protein sample is in high salt solution, try ultrafiltration, dilution
with water and ultrafiltration again.
Alternatively, you can try desalting column and change into ammonium
bicarbonate, follow by freeze-dry.
Just some thoughts, hope it helps.

Du






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