Protein solubility after amm.sulphate precipitation

Malini Madiraju malini at
Thu Apr 24 10:14:54 EST 1997

Dear netters,

I have a unique problem. My protein doesn't to go into solution after
ammonium sulphate precipiation even though it was soluble before

I do the following before amm.sulphate precipitation: Elute the protein
from nickel affinity column, dialyse it into a buffer (8mM imidazole,
500mM Nacl, 10% glycerol, Tris-Hcl, 20mM, pH 7.5). Protein is soluble at
this point. Then I do amm. sulphate precipitation. The ppt is now
insoluble in the same buffer. I do ammonium sulpahte precipitation to
concentrate the protein. 

I welcome any comments, suggestions or references that could help me
solve this problem. Thank you.

Malini R. Madiraju

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