enzyme storage

Stephen R. Lasky, Ph.D. Stephen_Lasky at brown.edu
Tue Dec 27 09:23:18 EST 1994

In article <1994Dec25.150022.5600 at bay.cc.kcl.ac.uk>,
udbs061 at bay.cc.kcl.ac.uk (MAHARAJAH) wrote:

> Most commercial firms sell their enzymes as suspension in 2-2.5M ammonium
> sulfate. You could try storing your enzyme by making your working
> in 2.5M ammonium sulfate solution in the desired buffer.
> Warning: Don't freeze the enzymes. store at 0-4 degree centigrade.
> It works fine with my enzyme.
> Please let me know the outcome.  As I am working on this topic.  I would be
> interested to know.
> sincerely
> sri

I'm not so sure about the statement that " Most commercial firms sell
their enzymes as suspension in 2-2.5M ammonium sulfate".  None of my
Restriction enzymes, proteases, nucleases, kinases, polymerases, or
phosphateses come in amonium sulfate.  I'm also not sure about "Don't
freeze" either.  Some enzymes are cold labile (I seem to remember that one
of the glycolytic pathway enzymes, maybe G3PDH) is cold labile (and is
stored in amonium sulfate as well), but freezing at -80 (or storage as a
liquid at -20 in a solution with glycerol) seems to be a fairly common way
of retaining enzyme activity.  What you don't want to do is to freeze and
thaw repeatedly.  Important enzymes justify the work to make small
aliquots in lots of tubes.

Some enzymes are stored the way you describe, but I think that, as has
been pointed out in earlier posts on this subject, one must determine what
conditions are best with any particular enzyme; one size (condition)
doesn't fit all.


Stephen R. Lasky, Ph.D.
Roger Williams Medical Center/Brown University
Phone: 401-456-6572       Fax: 401-456-6569       e-mail: Stephen_Lasky at brown.edu
"To me at least, 'Yuck' doesn't capture the full essence of death by
neurotoxin."   -Dick Dunn

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