Re: [ccp4bb] effect of high salt on protein

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CCP4bb <-- 2007 <-- April 2007 <-- 07 April 2007

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Subject: effect of high salt on protein
From: bputcha bputcha {- at -} UTK {- dot -} EDU
Date: 2007-04-07

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From: Swanand Gore swanand {- at -} GMAIL {- dot -} COM
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Subject: Re: effect of high salt on protein
From: Artem Evdokimov artem {- at -} XTALS {- dot -} ORG
Date: 2007-04-07

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:CCP4BB@JISCMAIL.AC.UK] 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

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CCP4bb <-- 2007 <-- April 2007 <-- 07 April 2007

Previous message:
Subject: effect of high salt on protein
From: bputcha bputcha {- at -} UTK {- dot -} EDU
Date: 2007-04-07

Next message:
Subject: Re: CNS query
From: Swanand Gore swanand {- at -} GMAIL {- dot -} COM
Date: 2007-04-09