Frozen restriction enzymes

[Steven Goldberg]

In article <32636179.28DE at pharm.med.yale.edu>, michaels at pharm.med.yale.edu
wrote:

> Hi Netters,
> 
> Here is my quick question:
> What happens when a restriction endonuclease solution is frozen to -80C?
> Is it normal for the 50% glycerol storage solution to solidify at this 
> temperature? I've heard sometime ago that if a restriction enzyme 
> freezes it is dead. Is this true? Thanks for any answers.
> 
> Mike

I clean out my -20oC freezer every year and put the restriction enzymes at
-80oC or on dry ice.  So far I have not noticed any that lose their
activity after thawing at -20oC.

Steve