Not sure if somebody mentioned it already, but have you played with
other buffers than the recommended sodium phosphate from the manual ?
Most lazy people use Tris because there's a 1 M stock solution - but you
can try also other buffers as long as you stay in a pH range >pH6 <pH10.
Of course you still need imidazole for the elution but the buffer might
bring some surprises, one of them can be a better initial purity after
the first capture step, another one might stabilize your protein.
Juergen
--
Jürgen Bosch
University of Washington
Dept. of Biochemistry, K-426
1705 NE Pacific Street
Seattle, WA 98195
Box 357742
Phone: +1-206-616-4510
FAX: +1-206-685-7002
Web: http://faculty.washington.edu/jbosch
