I purified a nuclear receptor once and it requires high concentration of
salt (>500 mM) to remain soluble. Other osmolytes (glycerol, non-ionic
detergents) can replace salt for nuclear receptors (confirmed). I also heard
(although have not tried it) that macromolecular crowding agents (PEG20K,
ficol70) can also increase solubility. The point is, many intracellular
proteins, especially DNA-interacting ones stay stable in a "crowded"
environment (the cytosol and nucleoplasma are crowded).
The selection of crowding agents will depend on what experiments you will do
with your purified proteins.
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Sent: Monday, January 21, 2008 2:03 AM
Subject: Proteins Digest, Vol 32, Issue 11