Precipitations in protein dialysis - (Oct/27/2011 )

Hi all,

Is there anybody who dialysed protein? I met some troubles when carrying out protein dialysis.

My protease was precipitated. I guess that the reason here is because of the high protein concentration. I diluted at a ratio sample : dilution buffer = 1 : 9

My dialysis buffers contain 20mM TrisHCl pH7.0, 100mM NaCl, 5mM Imidazole and the decreasing concentration of urea.

So what should I do to solve this problem? Would anyone mind suggesting me some possible solutions? I wonder that whether it worked successfully if I dilute it again with the same previous dilution buffer?

I regularly dialyze proteins. If you think it is a protein concentration issue, try serial dilutions of the enzyme in buffer (1:2 , 1:10, 1:100). If it still precipitates at higher dilutions, it is your dialysis buffer which needs adjusting. Common additions to dialysis buffers include 100 mM EDTA, 10% glycerol and higher NaCl concentrations.