Brian C. Thomas bcthomas at
Thu Jun 29 09:39:38 EST 1995

In message <3stjlc$f13 at> - william at (William Sun) 
:>Hello all,
:>Anyone know the percent of glycerol in most of the commercial restriction
:>enzymes?  I want to add glycerol to my protein samples to prevent 
:>freezing at -20 C. Thanks for the info.

Commercial enzymes are usually in 40-50% glycerol solutions.  However, 
15-20% is usually adequate for protein stabilization.  We routinely use 20% 
in preps of our enzyme (a chloroplast ribonuclease).  At -20oC, you won't 
freeze with this amount of glycerol, but at -70oC, depending on the volume 
and the length of storage, it will sometimes freeze.

Hope that helps, if you want a reference for this info, look in the Scopes 
book, "Guide to Protein Purification."

See Ya,


*                                          *
*   Brian C. Thomas                        *
*   University of Kansas                   *
*   Department of Biochemistry             *
*   Lawrence, KS 66045                     *
*   bcthomas at            *
*                                          *
*   'Biochemistry is the Splice of Life'   *
*					   *

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