Promega Taq, Summary
pfoster at bu.bu.edu
Mon Jun 7 20:00:44 EST 1993
My thanks to the many of you who replied on the Net and in Email to my
query about Promega's Taq. In summary, let it be said that there is far from a
consensus about this enzyme. There are those who swear by it and those who
have sworn off it. Instead of giving specific responses, I think I can sort
the comments into three classes of problems.
1. Template-primer and preparation specificity. Of the two enzymes that
have been discussed (Taq and the Vent family), it appears that even for
the same user one may work better for a particular application (see John
Nash's post). So, a wise researcher may wish to keep a couple of enzymes
around so if one suddenly fails, the other may give results.
2. Buffer problems. Promega supplies Taq in two different storage buffers.
A has NaCl and Triton, B has KCl and Nonidet/Tween. I have had one strong
vote for B (Jack Kramer), but it also appears that the buffers may not be
the same for each lot. Any more information on this (I need to know -- see
below)? As for reaction buffers, the case is mixed -- some people (eg.
C. Silvia) swear by Promega's (contains Triton and is pH 9.0) and some
(Jack Kramer) by Cetus' (no detergent and pH 8.3). So is it possible that
different opinions about the rxn buffer reflect one person's using storage
buffer A and the other B? See the post from Duncan Clark for a home-made
3. Batch to batch variation. I have had reports of this about Taq from
Promega, GIBCO/BRL and BioCan, but not (so far) from Boehringer or Cetus.
However, I also got a response from the Promega rep (yes, they are
listening!) and he assures me that Promega stands behind its enzyme as a
polymerase no matter what the customer chooses to use it for. It might be
wise before buying a large amount to check a particular lot and see if you
can get Promega to sell you more of the same one.
4. What doesn't seem to be a problem is buying enzyme through Fisher.
Promega assures me that the enzyme comes directly from them, and there
doesn't appear to be any consistent relationship between a bad batch and
buying through Fisher.
Lastly, as to my particular problem with Promega's Taq, I am working
with the rep to get it sorted out. Just in case I am not the only totally
ignorant purchaser -- BE WARNED -- Promega also sells a sequencing grade Taq,
which is what I accidentally bought. I simply didn't know that there was
more than one enzyme in the catalogue. Anyway, Promega is sending me a trial
vial to determine if I can get the non-sequencing grade to work for me.
But, ah, I have to specify storage buffer A or B! Help!
Again, many thanks
Patricia L. Foster
Boston University School of Medicine
Boston, MA USA
pfoster at bu.edu
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