Frozen restriction enzymes

Dr. Duncan Clark duncan at genesys.demon.co.uk
Fri Oct 18 09:56:25 EST 1996


In article <goldberg-1810960827320001 at 140.176.74.203>, Steven Goldberg
<goldberg at bms.com> writes
>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.


One thing to beware of which came as a big shock is that it appears that
CO2 gas can get past the o-ring seals in screw top eppendorf tubes even
if the lids are tight. We only found this out because we had some enzyme
in a storage buffer that contained a pH sensitive coloured dye. Storage
in a box with dry ice caused a pH shift from around 8 down to 7 where
the buffer was 20m Tris. We assume that very weak carbonic acid was
formed in the 50% glycerol storage buffer. Our best guess is that the o-
rings contract just slightly more than the plastic the vials are made
of. So far we haven't found a solution to this. Our vials are from
Sarstedt. We are now very wary about putting certain enzymes for
shipping in dry ice. Now they wil go on wet ice. 

Duncan

 
-----------------------------------------------------------------------------
My mind's made up. Don't confuse me with the facts!
Duncan Clark
DNAmp Ltd.
http://www.genesys.demon.co.uk




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