[Protein-analysis] Recombinant Protein precipitate out under 20 mM KPB/100 mM NaCl ???

[Nico]

Hi, 

I am changing buffer for my protein, which was purified from Ni-NTA column.
Under 20mM KPB/500mM NaCl, it was good. But when change to 20 mM KPB/100 mM NaCl,
the protein precipitate out. What should I do? Change to Tris-HCl Buffer or.....

Please help me out,

Many thanks,

Nico