My project is purification protein and when I change solution by dialysis, my protein is precipitated at the time pH of solution is pI. So how to protein can dissolve again?
Thanks you!
For your reassurance: It is common that the pI value affects the solubility of a molecule (in your case a protein). Solubility is minimal in water or salt solutions at the pH that corresponds to their pI and it is often precipitated out of solution.
This is because: At the isoelectric point (pI or IEP), the pH is such that molecules/proteins carry no net charge. The net charge on the molecule is affected by pH of its surrounding environment and can become more positively or negatively charged. At a pH below their pI, proteins carry a net positive charge; above their pI they carry a net negative charge.
Depending on your protein you just adjust the pH significantly below or above its pI and presumably your protein regains its solubility.
Good luck!
If high pH gradients were avoided and stirring was gentle then you can redissolve the protein
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