A thing we frequently forget is that phosphate can be a precipitating agent try a phosphate grid screen, just like you would with ammonium sulfate. If your protein likes PBS, it may want to crystallize with phosphate
See Enrico Stura's footprint screen for example On Tue, Nov 15, 2011 at 5:25 PM, Jayakrishnan Nandakumar <sscna...@gmail.com> wrote: > Hi All, > I have an RNA-binding protein that I can purify out of bacteria in PBS > (Phosphate buffered saline;137 mM NaCl, 2.7 mM KCl, 10 mM Na2HPO4, 2 mM > KH2PO4), but which is insoluble in Tris/NaCl-based buffers. My guess would > be that the inorganic phosphates (by mimicking RNA) are binding the protein > to keep it in solution. My question is whether I can leave the protein in a > phosphate-based buffer (at lower salt maybe) to set up crystallization > trials or are PBS-based buffers not suitable for crystallization in general. > I have always used Tris/NaCl based buffers in the past. > > Thanks in advance for your suggestions. > Regards, > JK >
