Making your own TAQ polymerase: Issues?
David F. Spencer
dspencer at is.dal.ca
Mon Jun 16 16:50:06 EST 1997
In article <5nmkge$sb5 at bubba.NMSU.Edu>, dkim at nmsu.edu (D. KIM) wrote:
> I have read methods published in Nucleic Acids Research and in
> BioTechniques for preparing Taq polymerase produced by recombinant E.
> coli. I would like to try this out, and the plasmid is available via
> I do not know what are the legal issues involved in producing our own Taq
> for research purposes (as a PCR reagent). Is this illegal? Would I have
> to purchase some kind of license from Hoffman-LaRoche? Or, could it be
> done freely as long as it is not sold?
> Also, it is known that DNA Pol I-type polymerases, such as Taq, have a
> strong bias against ddNTPs, making them problematic for cycle sequencing.
> However, a single amino acid change (switch a Phe for Tyr) will remove
> this bias. I would like to know if I would be allowed to modify the gene
> for Taq polymerase by site-directed mutagenesis (and maybe remove the
> 5'-3' exonuclease, while I am at it) to make my own thermo-sequenase-like
> enzyme? Again, is this a legal problem?
This is a very interesting query and one which I began researching about a month
ago. First, you might like to go to Promega's web site to get the details of
their legal challenge of Hoffmann-La Roche's patent (which they "inherited" from
Cetus) for TAQ holopolymerase.
In the US, apparently an act of Congress about a hundred years ago exempted all
_government_ labs from claims of patent infringement and I believe this is
actually a condition of obtaining a patent in the US. So anyone at, say,
make TAQ (or anything else) without concern. The exemption for not-for-profit
labs (universities, hospitals) is not as solid although it had been generally
honoured until Hoffmann-La Roche, in their ongoing battle with Promega, decided
to publically name hundreds of university/hospital-based scientists whom they
claim used unlicensed TAQ. Their justification is that any lab that
research grants is in the _business_ of doing scientific research and thus not
exempt by traditional interpretations; nice touch, what? This suggests that if
your lab is in your garage or basement and you pay for your research out of
own pocket then you can make TAQ for your own use and H-LaR wouldn't take
court. I did hear of a challenge H-LaR mounted against a lab at NC State that
was making its own TAQ [this may have been in Science or Nature], but I've
heard the final outcome of that.
The interesting twist is that Hoffmann does not appear to have a patent for any
modified TAQ (that is other than the holoenzyme), specifically the Stoffel
fragment, one of several 5'->3' exo deletion mutants. The only patent for this
modification that I've found from web searches is that of Wayne Barnes for
KlenTaq, and the patent is quite specific about the modification. And in what I
regard as an ironic twist, the patent for the use of a 5'->3' deletion TAQ in
DNA sequencing is held by Promega, although the description of the specific
enzyme used is not consistent with either a Stoffel or KlenTaq equivalent and
I would speculate could be easily side-stepped.
As far as the binding site modification (F667Y) that removes TAQ's
discrimination against dideoxys, this is covered by a patent to Tabor and
Richardson (the full claims section in this patent is a mile long and covers
everything but the kitchen sink). T and R also hold the patent for the use
DNA polymerase in DNA sequencing (USB's, now Amersham's, Sequenase).
I'm sure that few people who use TAQ (in any form) realize that it has got to be
the biggest ripoff in molecular biology, and that is a very competitive
category. As another poster pointed out, because of the enzyme's unusual
properties it can be fairly easily purified, in large quantities, and in an
acceptable quality. The contents of the tube of TAQ polymerase that you pay $100
or more for cost less to produce than the microcentrifuge tube they're packaged
in. I estimate that even factoring in reasonable costs of growing the
cells and doing the purification that you can produce TAQ in-house for
about 20 units
(more likely much more) per penny. It's sort of like paying $1000+ for a
As to whether you can safely make you're own TAQ derivatives, I'm sure not
going to advise you. Were I considering this (and concerned about legal
complications) I would not likely broadcast to the whole world my intentions.
The big unknown here is that if some large company with deep pockets goes to
your department head or university president and says they intend to take legal
action for what they regard as patent infringement what do you think the result
would be? Particularly in as litigious a climate as exists in the US
(fortunately much less so here in Canada) the legal principles can become lost
in the costs (or implied potential costs) of defending yourself in court. On
the plus side, it would appear that Hoffmann-La Roche has no stake in this and
so presumable won't set their lawyers on you. The only clear patent of concern
here is for the F667Y and I don't know whether Amersham has paid Tabor and
Richardson for the rights to that or not. Clearly historically you should
nothing to worry about but it's hard to say whether Amersham would be small
enough to beat up on you just to make a point and intimidate others, which is
clearly part of Hoffmann-La Roche's strategy.
By the way you might like to get the PDB structures for TAQ and Stoffel which
are very good and quite useful in planning your experimental TAQ derivatives.
The usual disclaimers apply: I'm not now and never have been a lawyer and
do not pretend to give legal advice.
David F. Spencer, PhD
Dept. of Biochemistry
Halifax, Nova Scotia, Canada
dspencer at is.dal.ca
dspencer at rsu.biochem.dal.ca
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