Thanks for all your suggestions so far...as a quick reply to some: >You say the fractions are in equilibrium - how about keeping the oligomer >fraction each time and adding it to the subsequent preparation? I did this once. The equilibrium is sort of a gift that keeps on giving, but the problem is the amount it's giving. In the end, this might be the only way to go, but it's very tempting to find a chemical solution.
>Do you have a reducing agent in your solutions? I.e., maybe you are seeing >disulfides? For native preps I used 1mM DTT throughout...for the SeMet prep I used 3mM DTT. To confirm it's not S-Ss, I'm about to run SDS-PAGE lacking reducing agent. >Changing buffer from Tris/Hepes into phosphate or citrate or acetate, or if >higher pH borate? When I tried lower pH I used citrate. I might give the others a try. >Stay away from SDS/Triton because they will almost certainly kill your >crystallization and it will be hard, very hard if not impossible to get rid of them. Thanks for the tip! >Another person off the bulletin board suggested differing how cell lysis is >done I used sonication.
