Imidazole and Amicon concentrators

Randall C Willis willis at
Tue Dec 23 15:10:07 EST 1997

Bill Geese wrote:
> The protein is 32.6kD; the centricon cut-off is 10kD
> I dont detect it in the filtrate nor in the retentate (Bradford and SDS
> PAGE); it's as if it is getting stuck to the membrane in some way and
> is unable to come off.


We've had innumerable similar experiences and it is due to the fact that
your protein may indeed be stuck to the verify, scrape a
piece of the membrane off into a sample of SDS loading buffer and boil
the hell out of it for a while.  If it is stuck, Millipore and
Pall/Gelman also make concentrators which are supposedly lower binders
but, in our experiences, the Millipore product can be imperfect as
well.  I would suggest that you contact reps for each company and ask
for a sample of their concentrators.

Good luck,

Randall C Willis, Researcher
Biochemistry Research, Hospital for Sick Children
3522-555 University Ave
Toronto, ON

416-813-5933 (ph)  -5022 (fax)
willis at

Randall C Willis, Publisher
Aliquotes Press
Aliquotes: A Journal Of Molecular and Biochemical
              Humour and Information
58 Balfour Ave.
Toronto, ON

416-691-2921 (ph)  416-813-5022 (fax)
roger at

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