Louise, I used to always use frozen 50ml aliquots of trypsin (at -20). Now 
we make up PK dilutions fresh from liquid reagent so it's not such a problem 
as powders.

Tim Morken, B.A., EMT(MSA), HTL(ASCP)
Infectious Disease Pathology
Centers for Disease Control
MS-G32
1600 Clifton Rd.
Atlanta, GA 30333
USA

email: tim9@cdc.gov
       timcdc@hotmail.com

Phone: (404) 639-3964
FAX:  (404)639-3043




----Original Message Follows----
From: Louise Taylor <louiset@mail.saimr.wits.ac.za>
To: histonet <histonet@pathology.swmed.edu>
Subject: proteolytic enzymes
Date: Mon, 05 Jun 2000 15:32:43 +0200

Hi histonetters,

Can you give me some help with proteolytic enzymes used for IHC please?

Is it possible to make up stock solutions of trypsin or protease in advance
and freeze  them for later dilution before use? I have done this with
proteinase K with no ill effect, but I have no idea as to whether this is
feasible with the cruder enzymes. My particular problem is
protease(pronase), the dilution is so  small that it gives me the heeebie
jeebies just weighing it out.

Thanks in advance
Best regards
Louise taylor
PS. I know that there are commercially available digestion solutions, but I
am loath to use them due to the expense involved


Research Laboratory
Department of Anatomical Pathology
South African Institute for Medical Research
Johannesburg
South Africa








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