protein concetration

[Marc Visconti]

Hello 
 
I am currently expressing and purifying a recombinant protein, calculated
17 kDa,  with the pET-30 expression system from Novagen.  The system uses a
hexahistidine stretch and Ni-affinity chromatography for purification.  It
seems that I have a large yeild, and now concentration is a problem.  I am
currently using Ultrafree-20 low binding cellulose filters from Millipore,
but I seem to lose a large quantity of my target protein.  Does anyone have
any ideas or tricks that I may try to concentrate my protein prep to
roughly 1 ml?  Has anyone tried using dialysis and polyethylene glycol or
Sephadex?  Any help would be greatly appreciated 
-- 
Copyright 1995 Elmer Fudd. 
All wights wesewved.