Technical information > Problems with dialysis

Protein precipitation during dialysis against phosphate or Tris buffers (PBS or TBS) can be often caused by:

• Too low salt concentration (NaCl, KCl)
• Too high protein concentration
• Sudden pH changes
• pH of dialysis buffer close to PI of a protein

Therefore:

• Use at least 1000-fold excess of dialysis buffer
• Perform procedure at 4°C (at least 3 h, followed by a buffer change)
• Use at least 350 mM salt in the dialysis buffer
• Optional: 50% glycerol

Precipitated proteins are very difficult to refold. If possible, purify your protein again and apply other conditions for dialysis.