You have to judge using some sort of a biochemical or biophysical method. Yes, protein can be functionally/structurally impaired and yet still soluble - however there is very little reason to suspect this due to salt exposure - unless you have hard evidence.
I have worked with several proteins that did not like HIC purification because of the high salt in the loading stage and at the beginning of the gradient. However, these proteins ireversibly precipitated - you could easily tell they were unhappy. Many proteins will reversibly precipitate in high salt, hence the venerable practice of 'salt cuts' typically done with AS. Likewise some proteins did not like the low salt part of the gradient or being exposed to low ionic strength environment in general (people working with proteins from halophilic organisms have more stories of this nature). Concanavalin A is happy as a pig in mud when it's stored for years in saturated NaCl solution. It can be dissolved in saturated NaCl to hundreds of mg/ml. When salt concentration is lowered - the protein crystallizes out. So, I would suggest checking that your protein is functionally and/or physically intact, if you're worried. Artem -----Original Message----- From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of bputcha Sent: Saturday, April 07, 2007 7:19 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] effect of high salt on protein Hi all, I keep my protein at 1 M NaCl, at some stage of purification, for about 30 minutes. Protein does not precipitate out at that stage and susequently when the salt concentration is reduced. I would like to know if such a high salt concentration can perturb ( irreversibly) the structure or modify the protein. Are there any known cases? Thank you Dhurjati Dept. of Biochemistry, Cellular and Molecular Biology, Walters Life Science, # 406, University of Tennessee, TN, Knoxville, USA
