The other big problem with -20 freezers is that they so often are
"frost-free" these days.  The auto defrost cycles on these types of
freezers are very tough on antibodies and sensitive enzymes.  I
believe Jackson recommends diluting their antibodies in 50% glycerol
if you want to store at -20 so that they don't "freeze" but yet are
kept cold.  I don't know if that limits the damage by a frost-free
freezer but do know that the molecular biology types all stress that
their enzymes diluted in glycerol are still very labile if stored in
a frost-free freezer.

Tom


>Tom Phillips wrote:
>>
>>  I was surprised by Martin's experience.  I buy lots of Jackson
>>  antibodies (FITC, Cy3, Cy5, HRP; goat and donkey anti-mouse and
>>  anti-rabbit) and generally aliquot them out as 10 ul/tube and freeze
>>  and store at -80.  Once thawed, I dilute and use that day and throw
>>  any extra away.  They have been stable for years this way.  Tom
>
>The differences in our experiences might have to do with our respective
>speeds of freezing: -80 vs -20 (which was what I tried); 10 ul vs ~100
>ul (which I used).  Faster freezing is better, in my
>experience--probably allows less time for the liquid to partition into
>salt-rich and salt-poor fractions.
>--
>Martin Wessendorf, Ph.D.                        office: (612) 626 0145
>Associate Professor                             lab:    (612) 624 2991
>Dept. Neuroscience                      Preferred FAX:  (612) 624 8118
>University of Minnesota                 Dept FAX:       (612) 626 5009
>Minneapolis, MN  55455                e-mail: [log in to unmask]

--
Thomas E. Phillips, Ph.D.
Associate Professor of Biological Sciences
Director, Molecular Cytology Core Facility

3 Tucker Hall
Division of Biological Sciences
University of Missouri
Columbia, MO 65211-7400
(573)-882-4712 (voice)
(573)-882-0123 (fax)