Stability of recom. Fabs?

X pemanuel at umabnet.ab.edu
Mon Oct 16 11:35:04 EST 1995


> I am assuming that your protein is stored in some form of phosphate buffered
> saline solution.  If not you may want to check the pH and salt concentration
> for their effect on stability.  Purified (especially recombinant and, even
> worse, recombinant and refolded) proteins are notoriously more unstable,
> especially at low (<500 ug/ml) concentrations.  Are you storing the
> protein in a self defrosting -20C freezer?  If so the freeze/thaw cycles will
> wreck havoc on your protein.  You can try and stabilize by adding 50%
> glycerol or 0.25M sucrose.  My suggestion is try -80C for storage or, if the
> freeze thaw is a problem (you should try to quick freeze in dry ice ethanol
> and thaw at 37C until a small chunk of ice is still present before moving to
> 4C).  Hope some of these suggestions work for you.
> 
> Bob
> 
Dear Bob,
  The Recombinant Fabs are stored in PBS/1% glycerol.  I will try
increasing the glycerol to 20% as 50% is too difficult to handle.  Perhaps
low amounts of NP-40 or tween-20 would also help?

Some people have told me this problem is unusual and that antibodies
should be stable under any conditions.  This concerns me.  The proteins
are at low protein concentrations (200 ug/ml) and so you may be clode to a
reason.  I will try storing in the -80 C but my freezer is a manual
defrost so that cannot be the problem.  Thanks for you help.  I'll let you
know what happens.
   Peter



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