RE: [Histonet] PAS with Glycogen Digestion - Solution Not Working

From:"Mickie Johnson"

Diastase powder will dissolve in any water, but requires some calcium ions
to function. Thus it will not perform in distilled water, but will perform
well using plain tap water. Also, the diastase powder from sigma will work
well if only a very small amount of the powder is used. We always used just
enough to barely cover the bottom of a glass coplin jar and then fill with
tap water. I would expect 0.5 grams in 50 mls of water is probably too much.
Try using one tenth that amount or 0.05 gm in 50 ml. When there is too much
diastase in solution, enzyme conformation is inhibited and it  does not
work. Spokane water is quite hard. It always worked well at room temperature
for 20 minutes.

Mickie Johnson, B.S., HTL(ASCP)
Mohs Histology Consulting Services, LLC
  & Mohs Lab Staffing
2507 S. Manito Blvd.
Spokane, WA 99203
FAX   509-624-3926
Web: & 
This message is intended for the sole use of the addressee, and may contain
information that is privileged, confidential and exempt from disclosure
under applicable law. If you are not the addressee you are hereby notified
that you may not use, copy, disclose, or distribute to anyone the message or
any information contained in the message. If you have received this message
in error, please immediately advise the sender by reply email and delete
this message.
-----Original Message-----
[] On Behalf Of Rene J Buesa
Sent: Friday, October 24, 2008 8:38 AM
To:; McKnight, Tanisha
Subject: Re: [Histonet] PAS with Glycogen Digestion - Solution Not Working

Being an enzyme, you cannot use diastase in distilled water. You have to
prepare a diastase buffer at pH7 to dissolve the diastase and do the
digestion at 37ºC during 30 minutes. That will work.
Please, do not try to use saliva!
René J.

--- On Fri, 10/24/08, McKnight, Tanisha 

From: McKnight, Tanisha 
Subject: [Histonet] PAS with Glycogen Digestion - Solution Not Working
Date: Friday, October 24, 2008, 11:26 AM

Hi All:
I am in the process of working up a PAS Staining protocol. The PAS stain
is working fine, but I am unable to get my tissue to digest. I am using
.5g of Diastase in 50ml of DI water. I tried heating the solution in a
water bath for 30 min, 1 hour and 1.5 hours and it still looks the same
as the one without digestion. Could I be using the wrong Diastase? If
so, does anyone have any suggestions for a new product?
Tanisha Neely, HT(ASCP)
AP-Histology/Specimen Management


Histonet mailing list

No virus found in this incoming message.
Checked by AVG - 
Version: 8.0.175 / Virus Database: 270.8.3/1747 - Release Date: 10/26/2008
9:27 AM

Histonet mailing list

<< Previous Message | Next Message >>