In our lab we use both the Amicon Ultras and the Vivaspins (soluble and
What I can tell you is that me and a few other colleagues had the
experience (and still do) of specific soluble proteins precipitating on
the Cellulose membrane
of the Amicon. By switching to the Vivaspins, which have a
polyethersulfone membrane, the precipitation completely vanished.
This seems to be very protein dependend as many seem to be able to use
both systems with no or little problems.
I don't know if the type of membrane really makes the difference but it
could be a possible explanation.
I unfortunately have less expierence with these systems on membrane
proteins and I only know that both systems seem to work fine for
colleagues who work on membrane proteins.
Institute of Biochemistry
University of Zurich
Tel: +41 (0)44 635 55 02