TAQ contaminated with DNA?

Paul N Hengen pnh at fcsparc6.ncifcrf.gov
Thu Aug 25 09:00:27 EST 1994


 In article <magoldstein-2208942140030001 at modem73.ucdavis.edu>
 magoldstein at ucdavis.edu writes:

: Has anyone found that their Taq polymerase gives a nice ladder of
: background bands without the benefit of added template and in the absence
: of possible laboratory introduced contamination?

| I've heard that some years ago, DNA contamination in Taq was quite common,
| and that people trying to amplify sequences that were highly conserved
| (rDNA, etc..) would often get amplification products later traced to
| poorly purified Taq.  I was under the impression that this rarely happens
| anymore, but you never know....

The contamination problem may actually have gotten worse. From what I
understand... before the gene was cloned and manipulated... Taq was isolated
from the organism itself and therefore had genomic contamination. Now, with all
the cloned DNA and specifically engineered versions floating around, the enzyme
is isolated (purified?) from E. coli cells carrying the "secret" altered gene
cloned in a common vector. The likelyhood of getting contaminants in that type
of prep is probably much more of a problem for amplifying with primers to
vector sequences. Want to keep your proprietary sequence a secret?...eliminate
the DNA from the enzyme prep.

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* Paul N. Hengen, Ph.D.                           /--------------------------/*
* National Cancer Institute                       |Internet: pnh at ncifcrf.gov |*
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