I am not a big fan of sonication. Try changing your way of disrupting the cells.
I have compared sonication vs mechanical stress on several unrelated proteins, and for me a good old french press wins every time. If you want to get all modern and fancy, a cell disruptor gives similar results. Cheers, Mads Gabrielsen [Hide Quoted Text] On Mar 2, 2008, at 11:47 PM, Tim Gruene wrote: Hi all sorry, for offtopic query... I am trying to purify my protein by Ni-NTA affinity chromatography. After sonication as i centrifuge bacterial lysate, soon after 10 min whole lysates get precipitated during loading on the column and some time it remain soluble too. if i get purified through the column without precipitation, it gets precipitated during dialysis. I have tried lot, by chnaging buffers, increasing salt or deacreasing salt or no salt at are helpless. I do purifiaction in cold room. can any one suggest some solution? Thanks in advance. NSH -- Dr. Mads Gabrielsen GBRC, B217 Division of Biochemistry and Molecular Biology IBLS University of Glasgow Phone Office: 01413308119 G12 8QQ Phone Lab: 01413306449 UK E-mail: [EMAIL PROTECTED] ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.