Column chromatography with silica gel - (May/26/2007 )

Hi, I am extracting proteins from plant samples. I will resuspend the concentrated proteins in phosphate buffer. I will then separate the proteins by column chromatography. Can I use silica gel as the stationary phase? I was told that I shouldn't if the proteins are in phosphate buffer due to its polarity. Or should I use sephadex? Please advise.

No. Silica gel is best used for small molecules with relatively nonpolar organic solvent systems.
(NH4)2SO4 precipitation/ionic exchange column fractionation would be the starting step if you are dealing with large volume of extract. Gel filtration with Sephadex or Sephacryl resin will be used in the second step after sample dialysis/concentration.

thank you!