Concentrating recombinent antagens - hisTaged antagens purified and neen to concentrated (Feb/22/2006 )

Dear all,
I have been working on developing antigens from C.jejuni using baculovirus system. So far, I have 2 of my proteins which are insoluble. Therefore, I use 8M urea to over come this problem and this works just fine. I use HisTrap columns from Amersham to purify my proteins. But I only get ~20µg/5ml that is just to less for further work I need 1mg/ml. In addition, my purified proteins contain too much urea. My question is how do I concentrate my proteins in desirable buffer?
Thanx
okice

well tyou should use a more read-friendly font...
you can first dialyse them against urea.
Then you can use the TCA/Acetone precipitation method or a centricon column (from milipore) whith the appropriate cut off.