[ccp4bb] FW: protein induced precipitation of proteins?

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: protein induced precipitation of proteins?
From: Jerry McCully for-crystallizaiton {- at -} HOTMAIL {- dot -} COM
Date: 2007-12-03

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Subject: how to change a membrane protein into a water soluble protein?
From: Daniel Jin jin_xiechen {- at -} YAHOO {- dot -} COM
Date: 2007-12-03

Subject: FW: protein induced precipitation of proteins?
From: Jerry McCully for-crystallizaiton {- at -} HOTMAIL {- dot -} COM
Date: 2007-12-03

sorry for the repeats.

Jerry
From: for-crystallizaiton@hotmail.com
To: ccp4bb@dl.ac.uk
Subject: protein induced precipitation of proteins?
Date: Mon, 3 Dec 2007 09:25:51 -0800

Dear All,

Recently I was trying to crystallize a
complex of two proteins(40kD vs 20kD). TO my surprise, precipitates immediately
appeared in the solution even when I mixed these two proteins at about
1mg/ml. However, the individual proteins were just soluble and stable
in the same buffer. From the binding studies I knew that the affinity
between them was lower than 1uM therefore I could not purify the complex
by gel-filtration.

I checked the precipitates by SDS-gel. The majority of the precipitates were the bigger protein. I'd like to mention that the smaller one was a protein with the pI above 10.

Did the smaller protein induce the precipitation of the bigger one?

Does anybody know some tricks to avoid the
precipitation so that the protein complex could be concentrated enough
for the crystallization trials?

Many thanks in advance.

Jerry McCully

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CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: protein induced precipitation of proteins?
From: Jerry McCully for-crystallizaiton {- at -} HOTMAIL {- dot -} COM
Date: 2007-12-03

Next message:
Subject: how to change a membrane protein into a water soluble protein?
From: Daniel Jin jin_xiechen {- at -} YAHOO {- dot -} COM
Date: 2007-12-03